NOVEL NEAR-
D ABSORBING DYES
by
Stephen Nigel Corns
y
Submitted in accordance with the
requirements for the degree of
Doctor of Philosophy
Department of Colour Chemistry and Dyeing
University of Leeds
October 1990
REFERENCE
NOT TO BE BORROWED
CLASS KA"'
BOOK NUNi: Df-rt
THESES
KT 2-1031
To Mum,
Dad and
Paul
(III)
ACKNOWLEDGEMENTS
to
I wish
assistance,
of
this
I
to
also
the
for
like
would
to
be undertaken
members
his
advice,
valuable
(and wry sarcasm! ) throughout
the
of
his
Department.
Technical
the
My thanks
given
staff
during
the
course
this
allowing
are
also
the
of
extended
Department
life.
my University
both
Ian,
especially
have
they
contributions
valuable
for
D. M. Lewis
and Academic
my friends,
thank
for
Lancashire
Professor
and assistance
to
wish
thank
in
friendship
their
I also
in
and encouragement
for
Griffiths
Dr J.
work.
to
work
thank
sincerely
in
Leeds
made to
and
my
life.
Special
preparation
Finally,
late
of
contributions
missed.
their
without
me throughout
appreciable
my
assistance
in
the
text
this
my thoughts
Mr Len Dixon,
with
who have,
my parents
supported
and actively
culminating
education,
for
be reserved
must
helped,
always
question,
entire
thanks
to
towards
turn
to
my great
friend
thanks
I
so
many
owe
whom
the
content
of
this
thesis.
and inspiration,
for
his
invaluable
You are
sadly
the
(IV)
SYNOPSIS
New near-infrared
investigated
of
the
by varying
halves
two
give
molecule
d]indolium
and these
indication
of
relative
azo dyes
blue
in
The dyes
dyes
yet
colour.
prepared
Amax
to
proved
dyes.
donor-acceptor
proved
were
be the
to
being
the
most
bathochromic
monoazo
4-nitrophenylazo
residue.
intense
of
through
it
with
this
type
in
at
infrared
region
the
to
give
new
compounds
nitroso
PMO theory
with
poor
possessed
the
of
being
dyes
djindolium
at
organic
and many
dyes
a much sought
were
but,
the
good
dihydroperimidines
organic
solvent
after
property
of
infrared
by the
reaction
of
squaric
ethylene
and
Michler's
iodide.
The first
solubilities
of
with
narrow,
by reacting
obtained
solvent
2,2-substituents
obtained
with
dihydroperimidines.
squarylium
obtain
dyes
squarylium
800nm were
about
1-ethyl-2-methylperimidine,
methyl-benz[c,
accord
absorbing
2,2-disubstituted
to
this
squarylium
bathochromic
from
and
Michler's
with
iodide
d]indolium
prepared
bands
modification
was possible
Other
condensed
were
was
system,
acceptor
electron
The aza dyes
near-infrared
acid
solubility,
with
of
absorption
squaric
system
absorbing.
near-infrared
A series
dyes
most
1-ethyl-2-
and the
bathochromic,
1-decyl-2(1H)-methyl-benz[c,
and
ethylene
a qualitative
most
derivatives
and 5-nitroso
5-formyl
the
chloride
be the
powerful
as a potentially
as donor
gave
The N-alkyl-3-cyano-6-hydroxy-4-methyl-2-pyridone
investigated
1-decyl-2(1H)-
examined
strengths,
amongst
the
containing
The
and
these
of
values
donor
were
were
strength
to 4-nitrobenzenediazonium
electron
methylperimidine
limits.
ethylene
residues
were coupled
The
and accepting
wide
Michler's
iodide
dyes.
monoazo
within
have been
chromophores
donating
electron
perimidine,
methyl-benz[c,
to
the
the
of
dihydroperimidine,
residues,
donor-acceptor
absorbing
The latter
two
809 and 900nm respectively
in
dyes
acid
1-decyl-2(1H)-
absorbed
toluene.
dyes.
in
the
(V)
A modified
developed,
procedure
Reaction
highly
afforded
bathochromic
croconic
room
acid
aspects
polar
involved
aprotic
Dyes were
also
The thermal
been
compounds
with
The dyes
absorption
examples
from
obtained
absorbing
solubilities.
broad
presence
of
all
examined,
bands
the
with
low molecular
were,
which
extended
stabilities
using
infrared
standard
dye
classes
procedures.
of
prepared
acid
a non-
electrophilic
residues,
aromatic
were
which
the
near-
organic
coloured
into
of
catalyst.
and good
strongly
well
in
various
of
masses
however,
and photochemical
the
several
study
reaction
an alcohol
of
at
croconic
optimum
electron-donor
dyes,
dye
with
a kinetic
a weak acid
reaction
with
readily
between
the
of
of
Reaction
occurred
reaction
a low proportion
the
N-dialkylanilines
undertake
that
form
anhydrous
8-hydroxyjulolidine
of
to
indicated
the
was
gave a croconium
as it
condensation
new donor-acceptor
giving
infrared
in
solvent
iodide
interesting
the
of
m=x
was possible
using
chlorine-substituted
thus
it
in
830nm).
ca.
The reaction
The results
and arylamines.
conditions
1000nm.
Thus
(A
acid
3-hydroxy-N,
with
d]indolium
was particularly
temperature.
mechanistic
acid
croconic
of
be obtained
to
dyes
benz[c,
beyond
absorbed
synthesis
acid
of croconic
1- decyl-2(1H)-methyl
that
the
the
enables
which
readily.
for
solvent
due to
visible
their
region.
representative
in
this
work
have
(VI)
CONTENTS
Page
1
A SURVEY OF DEVELOPMENTS OF NEAR-INFRARED
ABSORBING
1
DYES
1.1
INTRODUCTION
1.2
CYANINE-TYPE
1.2.1
General
1.2.2
The True
1.2.3
Di-
1.2.4
Pyrylium
1.2.5
The Oxonol
Dyes
15
1.3
DONOR-ACCEPTOR CHROMOGENS
16
1.3.1
General
Characterisation
16
1.3.2
Quinone
Dyes
16
1.3.3
Azo Dyes
1.3.4
"Methine"
and Related
1.3.5
Oxocarbon
Dyes
1.3.5.1
Squarylium
1.3.5.2
Croconium
1.4
METAL COMPLEX DYES
44
1.4.1
The Phthalocyanines
44
1
NEAR-INFRARED
8
Dyes
12
Dyes
and Thiopyrylium
21
25
Dyestuffs
28
28
Dyes
37
Dyes
1.4.3
Metal
Complex
of
and Related
Dithiolenes
Dyes with
Heterocyclic
Compounds
48
Indophenol51
Ligands
RESULTS
Synthesis
2.1.2.2
Light
55
AND DISCUSSION
APPROACHES TO HIGHLY
2.1.2.1
of
Halochromism
BATHOCHROMIC AZO DYES
Intermediates
Absorption
perimidines
2.1.2.3
6
and Triphenylmethane
Complexes
2.1
3
Cyanines
Metal
2
3
Characteristics
1.4.2
type
DYES
60
and Dyes
Properties
of
the
55
Arylazo71
and Dihydroperimidines
of
the
Azo Dyes
83
(VII)
Page
2.1.2.4
Stability
2.1.3
Highly
Novel
Properties
Bathochromic
Synthesis
2.1.3.2
Light
2.1.3.3
Stability
2.2
METHINE
Monoazo
(140)
-
Dyes Based
86
on other
90
Coupling
2.1.3.1
(135)
Dyes
of
Components
Dyes and Intermediates
of
Absorption
91
Properties
Properties
(162)
Dyes
of
AND AZOMETHINE
96
(163)
and
DYES DERIVED
102
FROM N-ALKYL-
103
3-CYANO-6-HYDROXY-4-METHYL-2-PYRIDONES
2.2.1
Synthesis
2.2.2
Light
2.2.3
Stability
2.3
OXOCARBONDYES
2.3.1.1
Squarylium
2.3.1.2
Synthesis
2.3.1.3
Light
2.3.1.4
Stability
2.3.2.1
The Croconium
2.3.2.2
Synthesis
2.3.2.3
Light
2.3.2.4
Stability
2.3.2.5
An Examination
Dyes and Intermediates
of
Absorption
Properties
Properties
-
(181)
-
(181)
106
113
115
Near-infrared
Absorbers
Dyes and Intermediates
Absorption
properties
Properties
of
(178)
Dyes
(178)
Dyes
of
Dyes as Potential
of
of
104
of
117
the
Squarylium
of
Squarylium
Dyes
Dyes
129
Dyes and Intermediates
Properties
Properties
of
the
of
122
127
Dyes
Absorption
115
the
of
130
the
Croconium
Croconium
Mechanism
of
the
Dyes
135
140
Dyes
Condensation
141
Procedure
2.3.3
Conclusions:
2.4
HIGHLY
Croconic
Between
The Oxocarbon
Acid
and Arylamines
Dyes as Infrared
BATHOCHROMIC DYES DERIVED
Absorbers
151
FROM ELECTRONEGATIVE
151
CHLORO-COMPOUNDS
2.4.1
Synthesis
2.4.2
Light
2.4.3
Stability
of
Dyes and Intermediates
Absorption
Properties
Properties
152
156
162
(VIII)
Page
2.4.4
Conclusions
163
3
EXPERIMENTAL
164
REFERENCES
188
OF TABLES
LIST
7
dyes
Table
1
Examples
Table
2
Some commercially
important
Table
3
Pyrylium
dyes
Table
4
A comparison
of
cyanine
cationic
of
infrared
dyes
absorbing
8
13
pyrylium
analogous
thiopyrylium
and
14
dyes
Table
5
Comparison
monoazo dyes
of
by varying
acceptor
22
and acceptor
substituents
Table
6
Near-infrared
Table
7
Methine
based
dyestuffs
related
'Y'
24
monoazo dyes
absorbing
and
ring
on dicyanovinyl
28
derivatives
of
Table
8
Examples
Table
9
Near-infrared
Table
10
Phthalocyanines
of
1,3-indandione
absorbing
(87)
43
dyes
croconium
containing
36
dyes
squarylium
unsymmetrical
different
central
45
metal
Table
11
atoms
data
Spectroscopic
for
some
typical
examples
of
50
1,3-dithiolene
Table
12
Spectral
complexes
properties
of
dyes
indophenol-type
of
the
52
general
formula
Table
13
The effect
Table
14
Dihydroperimidine
of
(104)
electron
donor
intermediates
strength
on monoazo dyes
prepared
in
this
56
work
62
for
Table
15
synthesis
Structures
of
of
monoazo dyes
4-nitrophenylazo
dyes
(X = 4-02NC6H4N2)
67
synthesised
(IX)
Page
Table
16
Spectroscopic
data
derivatives
Table
17
the
4-nitrophenylazo
ortho
71
dihydroperimidines
of
Spectroscopic
for
data
for
the
and perimidines
para
4-nitrophenylazo
72
derivatives
Table
18
dihydroperimidines
of
A
PPP-MO calculated
4-nitrophenylazo
Table
19
20
A
PPP-MO calculated
Halochromism
for
values
max
representative
and perimidines
for
values
mm.
representative
Para
79
dihydroperimidines
of
ortho
79
dihydroperimidines
4-nitrophenylazo
Table
and perimidines
and perimidines
4-nitrophenylazo
representative
85
dihydroperimidine
Table
21
Thermal
ortho
and photochemical
coupled
22
Thermal
Para
23
of
representative
dihydroperimidine
4-nitrophenylazo
and photochemical
of
stabilities
and
88
representative
dihydroperimidine
4-nitrophenylazo
coupled
and
89
dyes
perimidine
Table
stabilities
dyes
perimidine
Table
dyes
and perimidine
data
Spectroscopic
for
dyes
4-nitrophenylazo
(162)
96
and (163)
Table
24
Amex values
PPP-MO calculated
for
dyes
(162)
and
98
(163)
Table
25
Absorption
26
Thermal
of
(162)
and
in
(163)
100
solutions
and acidic
neutral
Table
spectra
azo dyes
of
stabilities
and photochemical
dyes
(162)
102
and (163)
Table
27
Spectroscopic
Table
28
Comparison
A
Table
Stability
-
dyes
for
(178a)
of PPP-MO calculated
values
m=x
(178)
29
data
of
representative
(181c)
-
107
and representative
dyes
of
type
109
-
(181c)
114
(181)
properties
of
dyes
(178a)
(X)
Page
Table
30
Near-infrared
dihydroperimidine
absorbing
based
118
dyes
squarylium
Table
31
Spectroscopic
Table
32
Comparison
data
for
dyes
new squarylium
of PPP-MO calculated
122
and experimental
125
absorption
maxima
Table
33
Stability
Table
34
Absorption
spectra
Table
35
Comparison
of
of
representative
properties
of
the
the
of
dyes
squarylium
128
dyes
croconiwn
PPP-MO calculated
dyes
squarylium
136
and experimental
137
for
values
Table
36
representative
Stability
properties
dyes
croconium
of
selected
dyes
croconium
in
140
Table
37
cellulose
acetate
The rates
of
film
formation
dye
of
in
(204)
pure
selected
144
Table
38
30°C
solvents
at
Relative
rates
of
formation
of
(204)
in
solvent
mixed
146
at
systems
Table
39
31°C
The effects
of
on the
additives
rate
formation
of
of
148
(204)
Table
40
(90% toluene
Visible
derived
Table
41
Visible
derived
Table
Table
42
43
absorption
from
Comparison
Table
44
Comparison
of
Table
45
Stability
Table
46
Spectrometer
uv-visible
of
properties
spectroscopic
dyes
156
of
properties
spectroscopic
of PPP-calculated
spectra
Stability
26°C)
dyes
156
2-chloro-3,5-dinitro-thiophene
absorption
absorption
at
(212)
absorption
from
: 10% n-propanol
of
dyes
and experimental
derived
PPP-calculated
spectra
properties
properties
settings
spectra
from
from
of
pyrroline
based
of
thiophene
based
used
(212)
and experimental
of dyes derived
for
recording
158
159
(213)
dyes
162
dyes
162
164
(XI)
Page
Table
47
Yields
data
and characterisation
for
the
168
dihydroperimidines
Table
48
data
Characterisation
for
the
ortho
coupled
perimidine
170
and dihydroperimidine
Table
49
monoazo dyes
data
Characterisation
for
the
para
coupled
perimidine
171
and dihydroperimidine
Table
50
dyes
monoazo
data
Characterisation
for
dyes
derived
from
5-formyl176
and 5-nitroso-2-pyridones
Table
51
Yields
Table
52
Characterisation
data
for
the
Table
53
Characterisation
data
for
dyes
LIST
OF FIGURES
Fig.
1
data
and characterisation
Idealised
(214)
-
dyes
180
(218)
186
for
curve
178
dyes
squarylium
croconium
absorption
uv-visible
for
an infrared
1
dye
Fig.
2
Fig.
3
Fig.
4
UV-visible
Fig.
5
(a)
Disposition
Absorption
Fig.
(a)
Fig.
7
(a)
Fig.
8
(a)
Fig.
9
UV-visible
in
state
changes
state
changes
Ground
density
state
changes
Ground
density
for
spectrum
Ground
density
molecular
spectra
Ground
density
6
of
state
changes
charge
for
the
charge
for
the
charge
for
the
charge
for
spectrum
dichloromethane
of
the
of
for
orbitals
symmetrical
dye
(130g)
densities
cyanine
in
i. r.
a typical
dye
5
dyes
76
dichloromethane
and
(b)
2
n-electron
80
first
band
absorption
densities
and
(b)
of
(130h)
n-electron
81
first
absorption
densities
first
and
(b)
and
(131h)
n-electron
band
(b)
absorption
protonated
of
82
absorption
densities
first
band
Michler's
of
(134b)
n-electron
band
of
83
(135b)
ethylene
94
(XII)
Page
Fig.
10
(a)
Ground
state
densities
charge
(b)
and
n-electron
99
density
Fig.
11
for
changes
Ground
state
the
transition
visible
densities
charge
dye
of
(163)
density
and n-electron
111
Fig.
12
changes
for
Ground
state
the
transition
visible
densities
charge
dye
of
(178a)
density
and n-electron
112
for
changes
Fig.
13
Absorption
the visible
transition
for
spectra
dyes
of dye (179a)
(192)
(189d)
and
in
123
di chioromethane
Fig.
14
Ground
state
densities
charge
density
and n-electron
126
Fig.
15
changes
for
Ground
state
the
first
band
absorption
densities
charge
dye
of
(189a)
density
and n-electron
127
for
changes
Fig.
16
'3C-n.
Fig.
17
Visible
m. r.
the
of
first
band
absorption
anhydrous
- near-infrared
croconic
acid
spectrum
of
dye
of
(194)
132
dye
in
(203)
136
di chioromethane
Fig.
18
Ground
densities
charge
state
density
and n-electron
138
for
changes
Fig.
19
Ground
the
changes
for
Fig.
20
Rate
formation
Fig.
21
UV/visible
22
Effects
spectrum
Fig.
23
Visible
densities
first
of
acid
(203)
density
and n-electron
band
absorption
of
of
in
(204)
dye
in
(208)
at
n-propanol
acid
croconic
dye
of
30°C
143
toluene:
147
mixtures
solvent
of
dye
of
139
spectrum
n-propanol
Fig.
the
band
absorption
charge
state
of
first
and base
croconic
acid
on the
of
148
: 10% n-propanol)
(90% toluene
spectrum
- near-infrared
absorption
uv-visible
dye
(217)
in
157
di chioromethane
Fig.
24
(a)
Ground
density
(215)
state
changes
charge
for
the
densities
first
and
absorption
(b)
n-electron
band
of
dye
160
(XIII)
Page
Fig.
25
(a)
Ground
state
charge
densities
and
(b)
n-electron
161
density
changes
for
the
visible
transition
of
dye
(221)
1
1.
1.1
A SURVEY OF DEVELOPMENTS IN
NEAR-INFRARED
ABSORBING
DYES.
INTRODUCTION
Since
chemistry
has
In
years
recent
from
the
that
beyond
700nm,
for
near-infrared
about
dyes
infrared
are
dye
infrared
visible
700nm
(Fig.
dyes,
uses
is
than
20,000
that
light
light
absorb
dyes
areas
latter
the
have
been
and still
were,
by a dye
absorbed
observer.
the
applications
minimal
a narrow
1mo1-'cm-1)
dyes
polymer
human eye and so
the
the
to
and possess
region)
because
in
infrared
traditional
to
show ideally
ie.
and other
is
It
Although
in
notably,
textiles
of
absorbing
use.
has,
effort
fields.
invisible
technology
of
coloration
undetectable
should
(emax greater
moved away
This
750nm is
dye
focus
technology
their
in
advances.
of
greatest
restricted.
many high
For
(the
find
many years
severely
beyond
new high
1856 research
and has made many significant
the
areas
in
Mauveine
of
intensive
however,
into
sphere
are
been
traditional
substrates
known
discovery
Perkin's
at
absorption
between
absorption
intense
the
spectrum
absorption
desired
point
of
400-700nm
band
beyond
1).
Ai
700rm
400nm
A
A=
Absorbance
A=
Wavelength
Fig.
1:
Idealised
uv-visible
absorption
curve
for
an infrared
an
dye.
2
Such demands
structure
molecule.
molecular
orbital
(LUMO) must
orbital
time
the
of
occupied
on a dye
other
the
energy
(eck. HOMO-1
º
in
energy
than
greater
unoccupied
or
high
to
300KJmol-1),
AE
order
to
characteristics
chromophores
the
chemist
developed
or
in
obtain
their
colour
molecular
a
n-electron
is
to
develop
this
necessary
quest
the
Therefore,
to
the
same
absorption
of
2 ).
5 150KJmol-,
HOMO-1
structure
either
design
and colour-related
to
the
of
investigation
theory
dye
a typical
dye.
dye
traditional
modify
chromogens,
and to
theory'
orbital
of
i. r.
such
with
new dye
PPP-molecular
the
for
orbitals
completely
for
specifically
relationships'.
quantitatively
of
it
the
At
----HOMO
-ý--ý--
In
molecular
-- --LUMO
---------------------------
Fig. 2 : Disposition
highest
LUMO and HOMO-f
( Fig.
--------------------------
Energy
the
LUMO+1
300KJmol-'
-------
n-electron
less).
avoid
-------------------------
AEt
the
gap between
(150KJmol-'
narrow
transitions
(ideally
limits
severely
(HOMO) and lowest
be sufficiently
light
visible
Thus
be very
possible
LUMO+1) must
chromophore
-I
aid
has been
colour-structure
can now be applied
chromophores
properties.
in
order
to
predict
3
The major
dye
that
classes
give
to
rise
infrared
dyes
absorbing
are: i.
Cyanine-type
ii.
Donor-acceptor
iii.
Metal
Each
of
dyes.
chromogens
these
can be subdivided
classes
As indicated,
technology
dyes.
complex
the
but
Some typical
find
have
in
applications
include:
uses
dyes
near-infrared
also
further.
in
many uses
high
technologies.
more everyday
-
i.
Solar
screens
(eck-. car
ii.
Laser
screens
(eck. military
iii.
Solar
heating
(eck. salt
windscreens/windows
uses;
water
etc.
protective
).
goggles
etc.
).
horticultural
evaporation;
plastics).
iv.
Optical
data
v.
Thermal
imaging
vi.
Infrared
camouflage.
vii.
Security
printing.
viii.
Machine-readable
ix.
Laser
dyes
storage
processes.
systems.
(infrared
developments
Synthetic
systems.
fluorescent).
in
the
main
infrared
dye classes
will
now be
reviewed.
1.2
CYANINE-TYPE
1.2.1
General
dyes
the
Williams
in
several
years
DYES.
Characteristics
The cyanine
discovered,
NEAR-INFRARED
first
1856°
The cyanines
were
the
example
although
its
first
being
class
(1),
structure
of
synthetic
be
to
by Greville
discovered
was not
dye
determined
until
later'.
permit
perhaps
the
simplest
way of
obtaining
systems
4
EN
H11C±N
-CSH11
x
(1)
that
absorb
were
in
well
fact
the
into
the
first
to
cyanines
have
been
used
and they
have
been
the
type
A cyanine
is
that
(2b)
or
(2c).
The true
(2b)
is
representative
= CH-}w
of
time
least
two
of
the
spectrum,
and
Commercially
purpose.
as photographic
sensitisers
much research3.6-10.
as any conjugated
hydrocarbon,
equivalent
are
cyanines
the
of
this
can be defined
interest
theoretical
X-+CH
a long
for
an odd-alternant
with
by at
of
for
chromogen
isoconjugate
region
be developed
subject
be represented
are
near-infrared
as in
cations
(2a;
The free
(Y=O).
oxonols
and that
forms,
resonance
system
can
eck. (2a),
X=N) whereas
(2c)
radicals
only.
X+
CH = X'
= CH-F-
CH = CH-)R
X
(2a)
Y--4-
CH =Y
CH = CH -}n
NI
10
CH-(-- CH = CH--)-
Y=
Y-
(2b)
CH
CH
Z--4=
-*
CH =Z
CH---
Z=
99
CH = CH--}-
Z-
(2c)
As such
systems
dyes
Cyanine-type
(2a),
(2b)
absorption
and
(2c)]
band
with
several
along
prevail
will
uniformity
have
where
the
resonance
the
increasing
chain
are
groups
length.
Thus
A
number
amount
of
for
vinylene
each
groups
additional
increases
vinylene
the
group.
bond
of
max
of
This
the
is
[as
identical
displacements
show non-convergent
degree
chains.
conjugated
terminal
a high
forms,
of
the
visible
increasing
dye by the
termed
the
in
the
same
5
"vinylene
shift"
is
and experimentally
found
to be about
100nm (Fig.
3).
WI
1
visible
l
IR
3
"s
n: 2
40000
2II
1+
^=4
^='
F 160,000
Oc
Et
Et-N
eQaoon-a
Al
n: s
400
800
600
1000
A InmI
---".
3:
Fig.
dyes
Cyanine
increase
the
decrease
significant
long
very
colour,
in
for
there
to
order
the
If
two
density
electron
though
such
a system
for
is
5) there
n=
with
3).
in
the
example
will
be present
is
isoconjugate
ever
will
class
doubtful
visible
As it
system
the
with
system
a truly
molecule.
are
of
distribution
a non-symmetrical
in
is
be developed.
cyanine-type
(3),
that
a
Thus even
and so retain
is
Therefore,
even
an odd-alternant
Ac
Ac
N-{-
N`
CH = CH -)-ý, CH =N
(3)
as
a
bonds in a cyanine-type
it
absorption
groups
However
disadvantage.
be
a
can
5 double
dye of this
terminal
basicities,
differing
infrared
250,000).
(Fig.
light
visible
initially
that
accompanied
coefficient
absorb
to be at least
ca.
beyond
curve
some applications
obtain
(up to
absorption
extinction
dyes
infrared
colourless
of
for
length
dyes
cyanine
coefficients
(particularly
the
in
chain
which
usual
of
symmetrical
extinction
chain
increases
flattening
general
high
possess
length
for
spectra
increasing
with
chain
the
Absorption
CH-{-CH
=
CH-}=
N
6
hydrocarbon,
bond
and has
alternation
groups,
vinylene
infrared
achieve
dyes
namely:
a)
True
b)
Di-
c)
Pyrylium
d)
Oxonols.
it
as the
occurs
value
Thus
As a consequence
is
of
a
number
of
much more difficult
to
can be subdivided
into
chemically
several
-
cyanines.
and triphenylmethane.
and thiopyrylium.
The True
Cyanines
definition,
By strict
encompasses
ie.
N;
one that
that
system
terminal
possesses
has been broadened
definition
this
cyanine-type
any
is
dye
a cyanine
but
residues,
quinoline
atoms,
of
amount
absorption.
Cyanine-type
categories,
A...,
the
a significant
'.
be present',
increases.
n,
forms,
resonance
may actually
displacement
convergent
1.2.2
several
and now
terminal
contains
nitrogen
(4).
= CH-f-CH
CH=N
N--{- CH = CH-h,
N
= CH-}n
\/\
(4)
Table
typical
1 lists
that
can be appreciated
it
group
vinyl
max
are
the
considered
groups
the
sizeable
it
vinylene
can be seen
red
shifts
is
(5a)
dye
coloured
magenta
illustrates
dye
shift
that
cyanine
of
examples
yellow
(5b)
is
in
can be effected.
This
obtained.
concept.
by choice
by adding
hue but
dyes
If
of
(5b)
appropriate
These
Table
From this
dyes.
a
in
shift.
and
(5c)
terminal
two particular
dyes
7
show the
also
in
shifting
alkyl
importance
absorption
(5c)
is
Table
is
(5b)
conjugation
extrachromophoric
to
maxima
dye
pyridinium
that
longer
magenta
the
this
In
wavelengths.
whereas
can play
alkyl
case
the
dye
quinolinium
blue.
1:
Examples
dyes",
cyanine
of
"
A
Structure
(5a) "
max/nm
480
(ethanol)
N"N
Et
Et
(5b)'ß
NN
Et
(5c)12
(ethanol)
(methanol)
604
(methanol)
Et
+
NN
Et
Et
for
Although,
1.2.1
Section
absorbers.
are
examples
It
558
562
is
worth
analogues
of
region
the
of
that
reasons
cyanine
They
are
given
in
noting
dye
(5c),
spectrum
have
dyes
of
nevertheless
Table
that
previously
potential
poor
generally
are
been discussed
infrared
importance
commercial
in
and some
2.
dyes
Table
due to
(8;
1, but
their
n=2)
(8;
and
now absorb
greater
n=3),
in
the
conjugation.
Table
2,
near-infrared
are
8
2:
Table
Some commercially
infrared
important
dyes13
absorbing
Structure
n
Me Me
(6)
me
Me
CH=CH -+-
+
A
r,ax/nm
2
6411"
3
741ýa)
1
782
2
708`a'
3
81
2
790
3
883`x'
I
CH
N
`/
Me
Me
\/
Me me
(7)
M°
CH=CH-
+/
I
I
CH
/
N
N
Me
Me
n
(8)
\
N
=CH --ý CH=CH
N
Et
Eä
(9)
CH=CH -)
(H3C)2N
(a)
(b)
(c)
- measured
- measured
- measured
1.2.3
Di-
in
in
in
dyes
(11)
are
The analogous
are of no value
an old
N(CH3)2
CH
ethanol
acid
Dyes
and Triphenylmethane
Triphenylmethane
Violet
ethanol
acidic
acetic
such
as Malachite
of
class
diphenylmethane
as near-infrared
(10)
lacking
the
third
and will
absorbers,
techniques
have
been
developed
for
and Crystal
dye.
cyanine-type
cationic
dyes,
Green
further.
Several
0a
displacing
phenyl
ring
discussed
be
not
9
Me2N
M02
NMe2
2
NMe2
(10)
absorption
region
maxima
of
the
(11)
of
Barker14
such
a system
are
bond
(12)
then
discovered
if
that
additionally
into
the
two of
near-infrared
bathochromic
fluorene
particular
the
phenyl
by means of
conjugated
an enormous
This
molecule.
dyes
spectrum.
1954,
In
triphenylmethane
is
shift
Me2N
a 2,2'-bridging
induced
malachite
of
analogue
in
rings
in
the
Green
NMe2
(12)
at
absorbs
(10)
850 and 955nm in
itself
shows
A different
dyes
introducing
phenyl
groups
by Akiyama
is
steric
removed
link
at
the
enhancing
an acetylenic
As a consequence,
bands
absorption
way of
was realised
98% acetic
acid
490 and 656nm.
of
conjugation
which
and co-workers",
into
crowding
the
between
and conjugation
Green
Malachite
whereas
is
ortho
also
involves
system,
resonating
the
triphenylmethane
as in
hydrogens
increased.
of
(13).
the
The size
10
R7
R
NMe2
H
+ eý
R
NMe2
II
+
NMe2
(13)
Met
(13b)
NMe2
(13a)
of
bathochromic
the
(13a)
resonance
example,
allene-quinoid
the
whereas
absorbs
at
727nm in
double
bond
absorbs
(13;
R=
N(CH3)2)
598nm for
the
A significant
seems to
shift
malachite
dichloromethane,
656nm'6.
absorbs
red
of
dye
shift
at
that
(13b)
resonance
ethynologue
at
parent
indicate
the
as well
is
(13;
Green
dye
R=
(14)
Crystal
of
dichloromethane
663nm in
For
present.
analogous
The ethynologue
as quinoid
H)
Violet
compared
to
(11)17-21.
can
also
be
imparted
to
triphenylmethane
ýNMe2
Me2Nýýý
NMe2
Me2N
Ö
A
max
a
with
656nm
=
(14)
NMe2
A
(acetic
770nm
max =
(15)
acid)
11
dyes
by extending
Thus
system.
Malachite
the
bathochromic
(10)
dyes
Bathochromic
and Crystal
[(14)
shifts
the
triphenylmethane
the
two
Crystal
are
and 613nm respectively
the
the
of
structure
parent
(11)
through
more
produces
respectively].
also
obtained
if
is
replaced
by a naphthalene
residue
Violet
of
Violet
(15)
and
directions
other
branches
the
extending
Green
in
conjugation
analogues
(16)
in
acid3.
acetic
and
the
one of
(17)
From the
623.5nm
maxima
absorption
Me2N
NMe2
,
NMe2
,
Me2N
NMe2
S.
(17)
(16)
(16)
and
through
(17)
the
is
it
apparent
that
than
1,4-positions
is
conjugation
2,6-positions
the
more effective
of
the
naphthalene
systems.
Both
(18)
to
of
concepts
effect
planarity
infrared
and extended
conjugation
are
absorption.
NMe2
A
max
NMet
(18)
(acetic
814nm
=
in
So
ring.
at
absorb
rings
phenyl
acid)
used
in
of
12
Although
triphenylmethane
dyes
cyanine
infrared
(by
a factor
colourless
1.2.4
Pyrylium
they
still
dye
(19)
number
is
Such a large
are
show visible
that
the
the
Thus a
absorption.
to
bathochromic
very
be synthesised.
bonds
bathochromic
between
is
shift
the
considering
the
even
terminal
oxygen
more surprising
when
Ph
.000
I
I-
in
similar
Ph
Ph
than
more photo-stable
Dyes
double
of
far
dye has yet
and Thiopyrylium
small
atoms22.
100)
triphenylmethane
The pyrylium
relatively
are
derivatives
absorbing
truly
of
dyes
I
p.
CH -{- CH = CH
Amax
1O4onm,
Emax = 125,000
=
(CH2C12)
(19)
Dewar's
atoms
than
rules
in
present
nitrogen
be more
not
are
the
pyrylium
and are
hypsochromic
found
to
be the
starred
than
the
case
to
cyanine
electron
symmetry
to
that
dyes
more bathochromic.
Drexhage22
pyrylium
with
the
equipped
dyes
are
assessed
the
in
light
source
with
a suitable
of
the
In
absorb
pyrylium
dissolved
samples
a Cary
Model
filter
to
at
longer
of
oxygen
system
of
in
with
light
is
carry
of
the
a series
should
to
degree
result
of
1,2-dichloroethane
14 spectrophotometer
eliminate
oxygen
this
practice
a greater
stabilities
relative
dye
resultant
reluctance
nitrogen
by irradiating
the
causes
as the
more electronegative
analogue.
increased
charge
prevail
both
pyryliums
positive
the
are
that,
predict
positions,
and the
the
compared
rules
system
at
Presumably
wavelengths.
These
considered.
below
that
650nm.
was
The-
a
13
relative
stabilities
(20a)
as a reference
Table
3:
of the dyes are compared
Pyrylium
in Table
3 using
dye
structure.
dyes"
cationic
rn
Ph
I=X
I+
Ph
Y
0
Ph
Dye structure
(20a)
0
Amax/nm(CH2C12)
Em=,, (x10'3)
1040
125
1
CH-t-2
Relative
stability
(20b)
XY
1090
140
76
(20c)
XY
1138
70
37
(20d)
XY
1145
143
178
CI
Comparison
incorporation
the
is
of
a cyclic
due to
cyclic
bridge
It
radicals.
at
sometimes
is
(20a)
(20b)
and
in
reduction
and the
dyes
longer
wavelengths
than
of
the
suffer
a reduction
in
extinction
the
carbon
species
containing
those
of
and enhances
deficient
from electron
apparent
centre
flexibility
of
3 shows
Table
the
shift
protection
that
in
into
residue
bathochromic
the
system
unsaturated
absorb
dyes
a significant
effects
This
of
with
that
systems
cyanine
dye stability.
chain
caused
atoms
of
the
such as peroxide
5-membered
rings
6-membered rings,
coefficients
by
but
and stability.
14
Dye (20d)
Dewar's
due
rules,
chlorine
at even longer
absorbs
atom
at
Thiopyrylium
to
the
attachment
an unstarred
dyes,
wavelengths,
of
by
as predicted
an electron
withdrawing
position.
x(21)23,
the
are
Ph
sulphur
analogues
of
pyrylium
Ph
+S
Ph
Ph
A
=
max
780nm
ca.
(21)
dyes,
and tend
4:
Table
absorb
(Table
counterparts
HOMO and
to
at
4)22
longer
due to
than
wavelengths
the
lowering
the
of
their
oxygen
gap between
energy
LUMO orbitals.
A comparison
Ph
of
analogous
pyrylium
thiopyrylium
and
Ph
Ph
X
x
CH=CH
CH
CH
dyes22
Ph
CI
C104-
(CH2C12)
Dye
x
(22a)
0
1072
107.0
(22b)
S
1160
105.0
dyes
Thiopyrylium
analogues.
in
than
is
A
Table
dye
less
3,
are
For
instance,
dye
(22b)
(22a).
This
electronegative
far
also
readily
than
than
more stable
when subjected
was found
is
. ax/nm
to
be at
explained
oxygen
to
emm=(X10-3)
the
least
pyrylium
as the
same test
25 times
by the
and so will
their
fact
dyes
more stable
that
accommodate
sulphur
the
15
inherent
to
positive
charge
more easily
in
which,
turn
the
stabilises
dye
degree.
a greater
Several
mixed
oxygen
terminal
recent
example
dyes
with
both
same molecule
have
been prepared",
Although
dye possesses
pyrylium-thiopyrylium
in
groups
being
the
(23)23.
this
sulphur
and
a
a secondary
CH = CH
0
(23)
visible
infrared
bands
coefficients
1.2.5
are
They
number
of
are
have
their
(24;
lmol-'cm-'
cyanine-type
dyes
has
also
with
extinction
respectively.
groups,
are
not
n,
of
shown that
increases.
any great
acyclic
absorbs
Hence,
practical
at
those
585nm and
(24;
/r
S,
lý\
sý
]ý
o-
0
(24)
26.
about
oxonols
acyclic
n=
x
\
at
as the
a few notable
value
absorb
the
of
(2b;
decreasing
with
Heterocyclic
than
formula
general
stability
oxonols
equivalents'.
0)
the
of
their
unstable,
wavelengths
n=
it
colour,
acetonitrile,
and 65,000
relatively
cyanine
much longer
example
anionic
they
Studies
a yellow
Dyes
vinylene
exceptions,
it
giving
744 and 824nm in
53,000
The Oxonol
Y=O).
at
at
of
Oxonols
than
band,
absorption
tend
series.
1) at
60nm less
to
absorb
For
650nM27.
16
As with
the
symmetrical
1.3
the
With
of
important
Two broad
of
is
It
infrared
one form
of
acceptor
from
Azo dyes.
c.
"Methine"
and related
d.
Oxocarbon
dyes
of
classes
another.
systems
and donor-complex
so far
systems
can be envisaged,
chromogen
category
the
that
acceptor
near-infrared
come from.
developed
into
subdivided
These
following
the
by Griffiths
acetone
naphthoquinone
dyestuffs.
(squarylium
dyes).
and croconium
absorbing
near-infrared
(25)
dyes
be surveyed.
will
and Chu28.
prepared
with
was somewhat
dyes
aniline
unexpected
(27)
dye
quinone
absorbing
are
derived
dye had an absorption
This
by the
in
but
reaction
ethanol.
1,4-
from
(26).
and 9,10-anthraquinone
near-infrared
and is
quinone
absorbing
near-infrared
The first
dye
as donor-
Dyes
Quinone
naphthoquinone
in
all
dyes.
b.
The known
or
and phthalocyanines
-
Quinone
1.3.2
non-
increases,
can be classed
colorants
latter
the
a.
These
as
quinones
donor-acceptor
can be further
dyes
categories:
'n'
the
non-convergent.
polycyclic
donor-acceptor
absorbing
are
organic
classes
donor-simple
systems'.
behaviour
discussed,
CHROMOGENS
exception
systems
namely
dyes
cyanine-type
Characterisation
commercially
acceptor
dyes
symmetrical
General
of
show convergent
DONOR-ACCEPTOR
1.3.1
classes
oxonols
the
whereas
other
of
was synthesised
maximum of
759nmn
5-amino-2,3-dicyano-1,4-
The red
PPP-MO calculations
shift
shown by this
confirmed
the
17
0
0
i
zýI,
-. 0
(25)
(26)
N
0
CN
1
ýI
0
NH2
(27)
highly
bathochromic
More
dyes
recently
has
been
nature
research
intense".
infrared
naphthoquinone
the
of
into
system.
the
near-infrared
30.
Matsuoka
dyes
of
absorbing
developed
and co-workers
the
(28 )31.32.
type
quinone
In
an
/
\I
H\
/H
ON1
NI
Ak_
S
O-1ý-, NI
H
(b)
(a)
(28)
investigation
of
the
tautomerism
was mainly
substituents
and also
(28),
the
dye
existed
tautomerism
influenced
the
polarity
predominantly
of
dyes
these
by the
of
they
nature
the
as the
concluded
and position
solvent.
quinone
For
that
of
example,
tautomer
(28a)
the
the
with
in
18
dimethylformamide,
more
dominant.
form
shown,
but
and
in
benzene
the
The analogue
(29)
is
incapable
of
course
tautomer
quinoneimine
in
was obtained
the
(28b)
was
quinoneimine
tautomerism.
of
II
IMe
..
JLi 11
OMe
U
N
.ý
(29)
(28),
Dye
which
absorbs
728nm in
2,3-dichloronaphthazarin
reacting
hydrogen
in
peroxide
Oxidation
acetic
at
and absorbed
colour
benzene,
(30)
(31).
aminobenzenethiolate
in
at
of
gave
acid
827nm,
with
potassium
(28)
(32)
by
was synthesised
by the
which
2action
of
brown
was yellowish
Scheme 1.
I
OH
O
ýII
OH
CI
NH2
CI
S
OH
N
K+
0
S
OH
(31)
(30)
IN'
(28)
H202/
CH3COOH
O
Tii
S,
O
IIý
ý
SýýO
N
HI*"
(32)
Scheme 1
19
Near-infrared
data
storage
reflectivity
A series
765nm in
media,
as they
in
solid
of
the
dyes
of
acetonitrile]
absorbing
1,4-naphthoquinone
absorbing
are
dyes
relatively
find
and have
stable
in
use
optical
a good
state.
type
(27)
[including
have
been
patented
(33),
for
which
in
use
absorbs
at
near-infrared
pigments33.
H5C2000
H
N_,,
CN
11
CN
0
NH2
(33)
The deposition
films
ultrathin
1,4-naphthoquinone
absorbing
for
of
optical
dye
This
recording".
the
containing
(34)
been
has recently
a long
dye contains
near-infrared
investigated
n-alkyl
chain
and
H25012
I
N
0
CN
11
CN
0
....
(34)
at
consequently
Blodgett
to
transferred
on with
written
dye
the
shift
to
absorbs
solvent/aqueous
a suitable
(monolayer)
is
film
at
with
775nm in
960nm was observed
The first
deposited.
substrate
an appropriate
a laser
near-infrared
interface
high
and,
for
anthraquinone
be
can be
example
Furhermore,
a remarkable
the aggregated
absorbing
can then
film
sensitivity.
chloroform
for
This
a Langmuir-
whilst
bathochromic
form.
dyes
were
developed
20
by Matsuoka
in
et
a similar
The anthraquinone
al.
to
manner
dibromoquinizarin
is
that
used
shown
instead
analogues
dye
of
in
Scheme 1 except
of
(30)35.
(28)
are
2,3-
that
dye
The resultant
Hý
made
(35)
\
N
Ig
__(
Y
i
N
H
(35)
absorbs
at
been
also
In
the
quest
anthraquinones
0
The selenium
chloroform.
and has a
prepared
in
properties
of
712nm in
for
black
liquid
the
of
mixtures
crystals
of
A...
720nm in
of
dyes
Matsumoto
general
formula
al
good ordering
discovered
(36)37.
a new class
Dyes of
NH2
i.
this
NH2
0
CN
has
chloroform".
with
et
(35)
of
analogue
type
NH'
NaOMe/MeOH/60°C
II\I/
NH
_/I\
CN
0
ii.
RNH2
NR
0
NH2
NH2
5/ODCB
5-95°C
o
^2
S
Amax
NH
S
NH2
(36)
Scheme 2
=
840rim
21
have
also
blue
greenish
to
been
since
absorb
in
shown
notable
shades
solar
polyester
to
textile
the
related
(37)
are
O
NH2
blue
in
light
ability
can be prepared
They
due to
shift
imides
fibres
an increased
heat38.
and accumulate
The bathochromic
the
since
dyeing
impart
which
energy
Scheme 2.
for
patented
the
sulphur
A...
with
as
is
atoms
ca.
600-
who,
in
650nm.
O
/1I\
N-R
OO
NH2
(37)
1.3.3
Azo Dyes
Azo chemistry
1858,
discovered
fortuitous
single
of
view
azo dyes
the
examples
were
of
only
If
of
have
become
is
it
rather
most
all
azo linkage.
of
that
research
that
surprising
azo dyes
absorbing
the
50% of
amount
vast
From these
indisputably
over
the
contain
Griess
acid39.
and well
and the
attracted,
developed
picramic
have
colorants,
dyestuffs
near-infrared
more donor
azo dyes
Peter
of
work
of
importance
few
very
known and even
are
these
recently.
very
a generalised
one or
the
class
their
the
diazotisation
important
commercially
In
the
beginnings
important
from
originated
(38)
structure
monoazo
X and Y are
groups,
is
considered
D is
where
or heterocyclic
carbocyclic
ring
Dn--X-N=N-Y-Am
(38)
systems
and A is
electrons
flow
of
Therefore
one or
from
the
the
donor
molecule
any modification
groups,
more acceptor
via
to
part
the
the
then
(D. -X-)
to
conjugated
(-N-
dye
structure
on excitation
the
that
part
acceptor
N-)
bridge.
lowers
the
22
ionisation
potential
affinity
of
dye.
the
i.
the
acceptor
There
are
increasing
donor
the
of
part
several
part,
induce
will
ways of
the
electron
the
number
increases
or
the
electron
a bathochromic
achieving
donor/acceptor
into
shift
this,
namely,
strength
of
D/A
respectively;
ii.
increasing
iii.
varying
the
relative
to
iv.
using
v.
increasing
Table
Table
5:
A;
groups
positions
of
attachment
of
groups
the
of
attachment
of
the
point
heterocyclic
the
instead
size
Comparison
of
acceptor
of
carbocyclic
and conjugation
54o 41 illustrates
and
D and/or
of
how,
in
monoazo dyes
'Y'40,4'
ring
of
considering
by
varying
D and/or
azo groups;
ring
the
A
systems;
molecule.
only
acceptor
the
acceptor
substituents
C2H5
R-N=N/N
CH2CH(OH)CH2OH
R
Structure
C\
A
..,.
/nm (methanol)
)/-
(39a)4'
420
(39b)
495
02N
/
N
ý--
(39 c )4'
s
N
Zý(39d) 40
(39e)4°
502
Cýv
McOC
s
s1
593
605
part
23
of
the
molecule,
bathochromic
it
nitro
group
(39a)
with
more
can
cause
(39c)
and
can
wavelength
acceptor
groups
relative
to
until
(39b)
than
be obtained
is
1986 that
describing
if
(39d)
used
of
the
ring
effect
and (39c)
a suitably
placed
thiazole
to
shift
of
system
these
and Bello
residue
3.
Scheme
been
Thus
established
first
the
published
longer
as in
it
(39e)
was not
paper
The dyes
dyes42.
monoazo
absorbing
in
long
have
principles
Griffiths
shown
as
were
2-amino-4-chloro-5-formyl
Cl
N
ý,,
ý-INH
\
+ NO'SO4-
OHC "'t,
S2
+
+N
Ar
S2
CN
(40)
CN
/I
0
CI
(42)
>--OHC
N=N-
S
(41)
CN
CI
;NN
ý
CH
-N
Ar
=N-
(43)
Scheme 3
thiazole
coupled
is
additional
with
thiazole
to
Comparison
A further
Cl
OHC-;
with
shows how the
a thiophene
of
(39b)
wavelength.
ring.
instead
near-infrared
prepared
longer
with
a phenyl
(39a)
incorporation
to
a shift
can be used
principles
(39d).
though
Even
how the
can be seen
bathochromic
above
Thus by comparing
shifts.
(39d)
with
the
of
several
(40)
to
the
diazotised
was
appropriate
in
nitrosyl
arylamine
sulphuric
(Ar-H)
to
give
acid
the
and
Ar
-H
24
intermediate
dyes
(41).
Condensation
dicyanomethyleneindan-l-one
(43).
The absorption
shown in
Table
(42)
6:
Table
of
gave
characteristics
(41)
the
of
with
3-
near-infrared
some typical
dyes
absorbing
examples
are
6.
Near-infrared
absorbing
CN
monoazo
dyes42
CI
CN
N
ý-CH
N=N-R
S
(43)
Structure
Äg,
R
Em. x/1mo1''cm-'
(CH2C12)
=x/nm
(CH2C12)
(43a)
NEt2
700
67,800
(43b)
NEt2
710
74,700
N(C3H7)2
716
74.000
750
82,600
NHCOCH3
(43c)
NHCOCH3
OCH3
(43d)
/
N(C3H7)2
NHCOCH3
It
can
acceptor
extended
be seen
groups
from
suitably
conjugation
Table
6 that
positioned
and heterocyclic
very
strong
electron
the
molecule
within
rings
are
necessary
donor
and
coupled
to
with-
obtain
25
near-infrared
absorption
A recent
(44)
by Gregory43
patent
in
systems
to
order
absorbs
obtain
ethyl
linkage.
one azo
describes
the use of disazo
near-infrared
706nm in
at
just
with
As with
ethanoate.
instance
For
absorption.
the
dye
dyes
previous
CN
02N
N=NN=N
NEt2
S
CN
type
of
(43),
dye
and so requires
that
note
dyes
class
the
broadest
generalised
carbon
azo
= N)n-
or
or
Not
maxima
bridge
double
chromogen,
if
(38)
except
to
near-infrared
important
another
they
are
less
commercially
the
ie.
bridge
dye can be likened
is
linkage
azo
C),
=
-,
-(C
the
C=
-C
acceptor
group
is
is
to
by a
replaced
C)n-,
-(C
dyes
the
are
classed
such
carbonyl,
dyes
as
may
as merocyanines.
the
to
shifts.
to
of
bridge,
the
same principles
longer
exhibit
increases
wavelength
do have
can be more readily
bonds
class
the
If
aryl.
The methines
tend
of
constitute
although
this
structure
azo dyes
bathochromic
systems
dye chromophores
stilbenes;
methines.
synthesis
interesting
azo dyes.
surprisingly,
of
is
It
conjugation
Dyestuffs
conjugated
be classed
also
extended
available.
sense,
equivalent
styryls
yet
of
route.
coupling)
and Related
than
the
In
not
concept
synthesis
(diazo
donor-acceptor
of
the
utilises
and related
important
-(C
is
"Methine"
Methine
(44)
a multi-step
a one-step
absorbing
1.3.4
(44)
NHCOCH3
the
extended
This
the
displacing
the
are
applicable
to
advantage
in
is
advantage
convergent
in
order
to
limited
behaviour,
bathochromic
that
shift
the
effect
the
conjugated
useful
though,
ie.
absorption
as the
progressively
because
number
the
of
decreases.
26
In
the
infrared
mid-1970's
a series
of
was discovered".
absorption
dyes
methine
that
possessed
Thus bindone
(45),
near-
(a dimer
of
OH
O
(45)
1,3-indandione)
heterocyclic
these
was condensed
with
to
for
enamine
infrared
dyes,
give,
which
are
a suitably
nucleophilic
(46)
example
merocyanines,
(47).
and
However
from
suffered
low
0
CH
B
Amax(DMF)
= 7621
70Onni
425nm
O
Et
(46)
N
Me
N
Me
Me
CH
ýmax(DMF)
841nm
=
782nm
41 3nm
Et
(47)
in
solubilities
in
the
More
Griffiths
visible
recently
organic
solvents
and showed
additional
peaks
multiple
region.
a related
series
They
and co-workers.
of
showed
dyes
has been described
how the
-CH/
A
481nm
(CH2C12)
max =
(48)
yellow
dye
NMe2
(48)
by
could
be
27
progressively
7).
in
modified
The carbon-bridged
the
(50)
desired
in
dye
(51)
as shown
+ OHC
in
derivative
ethanol
Scheme 4.
or
by condensing
(49)
acetic
with
4-
to
give
acid
The nitrogen
the
bridged
I
NMe2 ---º
(Table
absorption
7 were prepared
indandione
dimethylaminobenzaldehyde
infrared
obtain
dyes in Table
1,3-substituted
relevant
to
order
CH
NMe2
YV
(49)
(50)
(51)
Scheme 4
(azomethine)
to
manner
that
used
from
in
be related
the
(51b).
and
to
(or
central
theory
predicts
cause
site
will
the
central
causes
(52a).
molecular
that
a shift
to
Comparison
extrachromophoric
The azomethine
entity
orbital
an increase
in
longer
of
the
shift,
these
dyes
"unstarred"
an
and thus
occur
then
the
shows
the
The
position.
at
can
by
Dewar46,
electronegativity
as
as defined
an unstarred
of
replacement
atom
nitrogen
as shown by comparing
(52b)
and
of
the
with
red
hydrocarbon,
more electronegative
wavelength
(52a)
in
chromophore
to
shift
group
a marked
causes
(PMO) theory
atom will
atom with
a carbonyl
odd-alternant
a bathochromic
carbon
of
be at
bridging)
donor-acceptor
typical
fundamental
an isoconjugate
perturbational
N-
(50).
aldehyde
replacement
As the
a similar
4-nitroso-N,
that
the
of
dicyanovinyl
electronegative
(51a)
place
the
Thus
characteristics.
in
prepared
N-dimethyl-l-naphthylamine
7 exhibit
Table
were
Scheme 4 except
in
respectively
(52b)
and
4-nitroso-N,
or
The dyes
more
in
shown
dimethylaniline
were
(52a)
analogues
bathochromic
(51b)
and
effect
conjugation.
dyes
related
to
(52a),
Table
7,
have
the
advantage
of
28
Table
7: Methine and related
dyestuffs
derivatives
of 1,3-indandione45
based om dicyanovinyl
A
Structure
max/nm
Emax/lmol-'
(CH2C12)
CM-1
(CH2C12)
O
(51a)
CH
NMe2
557
55,200
NMe2
608
33,000
NMe2
755
25,500
NMe2
850
Unstable
CN
CN
CN
CN
(51b)
=CH
N
CN
CN
CN
(52a)
-N
CN
CN
CN
CN
(52b)
N
CN
CN
low
molecular
organic
solvents
of
of
majority
1.3.5
Since
Park47,48
the
excellent
general
this
dyes
currently
absorbing
is
solubility
in
uncommon with
the
available.
Dyes
Dyes
accidental
acid
squaric
preparation
imparts
turn
In
and polymers.
Squarylium
its
in
mass which
near-infrared
Oxocarbon
1.3.5.1
\/
of
discovery
(53)
near-infrared
in
1959 by Cohen,
has become an invaluable
absorbing
dyes.
Lacher,
and
intermediate
for
29
OH
OH
Ilý
O7
O
(53)
Squaric
2.2
(pK, z1)
1.5).
of
is
a white
and is
therefore
almost
as strong
a remarkably
stable
solid
acid
is
It
hydrogen
bonding,
aqueous
of
interpreted
al
anion
(54)
and has
solubility
the
was greatly
led
to
the
3% by weight
acid
resonance
point
intermolecular
293°C
about
room temperature.
at
stabilised.
This
squarate
that
and an
Cohen et
the
delocalised
ion
(pK2
acid
strong
of
as evidence
the
has a pK2 of
which
as sulphuric
strength
that
suggestion
acid
due to
a decomposition
ca.
high
dibasic
crystalline
squarate
structure
was aromatic,
and
z00
ö
.o
(54)
that
the
oxocarbon
of
is
This
series49.50.
(55),
anions
is
(54)
a hitherto
may constitute
a logical
deduction
Here
considered.
the
if
one of
cyclobutene
unknown
the
ring
aromatic
tautomers,
contains
two
fits
the
2H+
O_
o
(55)
charges
positive
Hückel
(4n+2)
spectroscopy
and so the
for
rule
and x-ray
The synthesis
of
ring
an aromatic
analysis
squaric
acid
has
two n-electrons,
ring.
soon
Evidence
confirmed
has proved
this
difficult
which
from
vibrational
hypothesis"'.
although
several
30
routes
are available3".
squaric
(56)
and hydrolysis
substitution
Cl
2
Cohen and co-workers
from chlorofluoromethane
acid
subsequent
For instance,
CFC1
(ý
F
CF2
FF
by dimerisation
in
as shown
and
(5).
Scheme
F
F
Zn
CI
10
FF
-ZnC12
FF
(56)
prepared
FF
(57)
(58)
KOC2H5
OH
EtO
OH
/
H+
OEt
H2O
44
FF
FF
00
(53)
(59)
Scheme 5
Commercially,
(60)
squaric
is
which
a by-product
hydrocarbons".
for
Thus
hours
several
reactions
at
desired
the
cooling
acid
the
from
the
of
diene
product
to
manufacture
is
heated
perchlorinated
80 and 1501C to
(Scheme 6 )5'.
reproduce
hexachlorobutadiene
70-96% sulphuric
with
between
temperatures
difficult
are
in
can be obtained
In
the
acid
give,
laboratory
on
such
efficiently.
OH
OH
i.
H2SO4
ii.
Cool
/
H2O
/
Heat
CC1=CC12
C12C=CC1
0
(53)
(60)
Scheme 6
In
1965 Treibs
with
squaric
give
intense
and Jacob
acid".
red-violet
examined
The components
coloured
the
reaction
reacted
condensation
in
of
pyrroles
a 2: 1 molar
products
(62).
(61)
ratio
to
31
Nucleophilic
ring
and not,
on opposite
been
in
carbons
expected,
at
the
4-membered
neighbouring
carbon
7).
R4
OH
OH
place
have
as might
(Scheme
atoms
took
attack
R3
R3
+2
001
O-
R4
ýR2
2
R2
NN
R4
Rý
1
0
(61)
R
(62)
Scheme 7
These
the
authors
pyrrole
positions
from
also
if
both
then
no reaction
unoccupied
then
mixtures
blue
to
green
that
occupied
were
were
showed
based
on structure
the
2- and 5-positions
in
if
However,
occurred.
of
dyes
with
(63)
were
obtained.
varying
both
colours
R2
H
(63)
is
It
for
reagent,
react
will
bond.
arylamine
to
form
heterocyclic
example
with
However,
is
that
recognised
generally
squaric
it
acid
should
reaction
used,
a carbon-nitrogen
with
enamines
the
if
Such dyes,
a carbon-carbon
of
a primary
at
preferentially
occurs
for
N/
OWN
t
Ö
(64)
or
secondary
the
nitrogen
example
Me
Me
CI
or N, N-dialkylarylamines
formation
that
be noted
bond.
nucleophilic
any sufficiently
N02
CI
(64)39
atom
tend
to
32
be yellow
in
a tertiary
at
the
colour
amine is
4-position
formed,
highly
and are
used,
the
of
insoluble
in
organic
such as N, N-dimethylaniline
If
reaction
and an intensely
arylamine,
solvents.
occurs
dye
coloured
is
eck. (65).
Me2N -
C\
/`
2'F1.
ße2
O_
(65)
(65)
Dye
the
with
absorbs
azo dye
630nm in
at
(66)
of
dichloromethane
similar
size
which
may be compared
which
absorbs
at
478nm.
This
aNN/
Me2N
NO2
(66)
illustrates
how much more bathochromic
to
when compared
other
The bathochromic
large
donating
system
is
group
then
(67).
is
nature
Here
the
This
predicts
a starred
bathochromic
overall
dyes
squarylium
of
at
placed
a large
squarylium
dye
is
chromogens.
by PMO theory.
extent
a simple
should
is
structure
if
that
position
shift
can be explained
a strong
in
to
a
electron
a cyanine-type
An extreme
result.
case
neutral
electronically
o-
\I/NPll
CH = CH - CH =CC30
C51 lar
CH = CH - CH = N'
CD,
(67)
but
in
a non-polar
fact
further
of
this
resonance
type.
bathochromic
form
Moreover,
shift
is
cannot
be drawn.
Dewar's
obtained
rules
if
Squarylium
also
electron
indicate
withdrawing
dyes
are
that
a
groups
33
are positioned
at unstarred
carbonyl
can be considered
group
1,3-squarylium
In the
sites.
be attached
to
to
dyes
two
such
(68) a
positions.
0'
N1*
CH = CH --PC=
or
10
CH V,
0
CH = N'
0
(68)
the
Additionally,
ring
dione
electronic
x-ray
will
resonance
are
readily
symmetry
data6O.
dyes
Thus
structures
accept
the
within
(65)
(I)
the
negative
molecule,
that
charge
as proved
may be considered
to
fact
by the
stabilised
the
4-membered
and that
by single
as a hybrid
of
the
there
is
crystal
various
(IV).
Me2N
ý---º
NMe2
Me-, N
(II)
I/
Ö
\
NMe2
2+
",
Me2N
(65)
00
NMe2
4"
Me2N
NMe2
\
0O
(III)
(IV)
34
Such
dyes,
impart
qualities
certain
to
characteristics
the
squarylium
namely,
a.
a large
b.
a narrow
c.
a high
d.
minimal
secondary
absorption
Squarylium
dyes
generally
the
presence
dye
are
synthesis
or
(Scheme
in the visible
8).
in
a 2: 1 mixture
demonstrated
(70).
acid
acid
in
Having
region.
that
the
this
obtained
is
the
solvent
system
These
results
indicate
refluxing
of
reaction
ester
necessary
that
n-butanol
proceeds
the
to
0
0
n-butanol
n-butanol
H2O or
OH
effect
the
0oOo
OH
band,
by azeotropically
obtained
and squaric
Law and Bailey"
water
absorption
and
di-n-butylsquarate
of
of the visible
shift
width,
nucleophile
and toluene.
the
band
intensity,
chosen
via
bathochromic
OH
HgC4O
H'
OC4Hg
H9C40
(70)
(69)
Nu-H
O-
Nu
H20
OH
Nu-H
Nu-H = nucleophile
'Nu
:2+..
Scheme 8
Nu
H2O
-
35
di-n-butylsquarate
precursor
of
is
hydrolysed
squarylium
(69)
to the monoester
This
synthesis.
was confirmed
and this
is
the
by Kuramoto
et
a162
Law and Bailey61
secondary
tertiary
or
successfully
showed
alcohols,
for
substituted
no reaction
solvent
also
that,
other
with
the
hydroxylic
and that
n-butanol
of
exception
can be
solvents
without
such
a
occurs.
1,2-Disubstituted
dyes,
squarylium
eg.
(71)
are also
known63-65
.
NK1e2
Me2N
0
(71)
They
are
in
stable
much less
acid
when dissolved
solution
in,
than
bathochromic
for
tend
example
to
ring
1,3-squaryliums,
the
open and polymerise
chloroform61.
O
Ar
neutral
Ar
Ar
'O
Ar
polymerisation
Scheme 9
and although
(Scheme 9)
36
Unsymmetrical
and in
some examples,
absorption
in
peak
8:
Table
dyes are also
squarylium
Examples
spite
the
of
of
their
uv-visible
known66.67.
asymmetry
8 lists
Table
they
show only
one
region.
unsymmetrical
dyes67
squarylium
R'
R2
o_
Structure
R'
Amax/nm
R2
(CHC13)
(72a)
Me2N
Me0
/1mo1-'cm-'
cm.
(CHC13)
579
53,700
590
53,200
592
53,500
F
(72b)
Me2N
MeO
Me0
Me
(72c)
Me2N
MeO
MeO
The visible
choice
region.
and
the
of
absorption
terminal
Examples
naphthylamine
amino
of
such
band
of
based
squarylium
be displaced
residues
dyes
dyes
include
system
the
(74)62.68
can,
into
quinolinium
the
with
suitable
near-infrared
derivative
(73)
37
oI
\
CH
_CH
Et
`-+
N
Et
0
Amax
732nm
(chloroform)
=
(73)
ýý
Me2N
NMe2
/
_.
lö
/\/,
A
716nm
=
max
(acetone)
(74)
In
general,
dyes
squarylium
to
the
stability
and a general
Such dyes
also
tend
However,
squaryliums
coloured
than
means of
obtaining
1.3.5.2
dipotassium
it
appears
potassium
isolated
infrared
is
broadening
have
to
have
salt
(76)]
trying
carbon
pure
heat
dyes.
by a decrease
offset
the
organic
band of
absorption
in
the
dye
band.
maximum absorption
solvent
solubilities.
and light
they
As such,
stability
and are
provide
a promising
dyes
absorbing
near-infrared
less
Dyes
(75)
from
low
the
of
better
colourless
acid
were
the
shift
cyanine-type
Croconium
Croconic
to
any attempt
was probably
synthesised
by Berzelius,
to
derive
a novel
and potassium
dipotassium
Wähler
and Kindt69
industrial
hydroxide.
croconate
originally
[as
who,
the
in
preparation
Two years
and croconic
UNIVERSITY
LIBRARY
LEEDS
acid
later
1823,
of
Gmelin
38
2OH
0
OH
Jl.
ooo
from
this
was in
mixture7O.
the
same year
illuminating
the
isolated.
of
may be aromatic
in
Michael
is
the
the
in
Faraday
first
ion
croconate
aromatic
acid
at
It
was not
the
aromatic
were
the
until
it
isolated
benzene
from
and benzene
must
share
to
have
been
were
fact
that
a lengthy
properties
of
a system
and so it
article
of
croconic
133
another
such
discovery
the
after
soon
for
appreciated
the
end of
because
properties
not
mentioned
interest
compounds
whose aromatic
passing
1959 that
historical
of
first
Yamada only
was overlooked".
acid
that
croconic
then
Even
date
benzene,
those
years.
This
being
of
Unlike
realised,
(76)
Thus
gas oil.
distinction
'0
ö0
(75)
2K'
squaric
acid
were
recognised.
Croconic
squaric
acid
itself
is
very
acid,
can be obtained
acid
Croconic
acid
characterised
a light-sensitive
hygroscopic.
initial
the
synthesised
is
yellow
when it
Consequently
is
product
the
trihydrate72.
by heating
the
slowly
decomposes
when heated
as the
dimethyl
ether
trihydrate
unlike
is
The anhydrous
at
above
120°C for
2-4
150°C.
It
may be
point
of
has a melting
which
that,
solid
hours.
11 3°C.
Surprisingly
route
alternative
Thus
via
the
desired
an a-oxo
rearrangement,
salt.
since
for
Gmelin's
its
discovery
(Scheme
synthesis
(77)
hexahydroxybenzene
rearrangement,
to
yield
which
the
dianion
of
is
10)73
to
in
the
an
been
has not
ring
undergoes
related
(78),
acid,
croconic
the
contraction
benzilic
form
found.
of
its
acid
metal
39
Q
2Ilk
0
r,
-o
iý
0
-o
)H
0
N
(77)
_0
/0
OH
0
C--OH
00
7101
.o
o,
(78)
Scheme 10
can be simplified
The synthesis
material
of
efficiently
(79)'2
or
a higher
oxidation
prepared
by the
acid
rhodizonic
somewhat
(80)"
HO
acid
barium
of
trihydrate.
A far
more
by
I/
\0
(80)
(79)
Treatment
followed
0
HO
HO
of
dioxide
manganese
HO
addition
is
acid
tetrahydroxy-p-benzoquinone
of
with
a starting
Thus croconic
state.
oxidation
by using
this
chloride
salt
with
Currently
amazing
in
to
order
warm dilute
croconic
synthesis
of
obtain
barium
mineral
acid
acid
croconic
is
not
acid
croconate.
offered
has
croconic
yields
commercially.
recently
been
40
by Hartley,
postulated
amounts
from
of
croconic
carbon
cloud
features
which
appear
Croconic
pointed
acid
would
of
to
in
created
for
account
the
this
to
appears
by Hirata
acid
the
cloud
top
is
a strong
region
Venus
of
and uv-absorbing
colour
Experimental
trace
uv-visible
have
results
been
obtained
theory.
have
a very
(Scheme
and co-workers
11)'x.
the
Normally
acid
H
0
OH
0--
00
as
structure
mobile
unusual
OH
OH
that
who suggested
the yellow
planet.
support
acid
out
are
and Travis74,
As croconic
monoxide.
this
absorber
Wolff
0
0
0
(II)
(I)
4p
.0
0H
0
0
OH
(III)
Scheme 11
is
to
considered
reacts
as the
by
decolorised
In
pyrrole
1973,
it
enediol
light
Treibs
based
be an equilibrium
the
croconium
structure
equilibrium
is
dyes
(81)76.
NN
H00H
(81)
-
When it
(III).
and when the
to
synthesis
The dyes
Me
Me
(I)
shifted
the
reported
R
Me
of
mixture
possesses
and Schulze
(I)
were
acid
(III).
of
several
unstable
and so
is
41
problems
were
were
in
green
squarylium
In
dyes
(82)
ring
were
far
the
However
purification.
more bathochromic
than
the
dyes
analogous
(62).
same paper
6-membered
their
and thus
colour
pyrroles
the
in
encountered
a series
oxocarbon
dyes
pyrrole
rhodizonic
in
violet
of
derived
(80)
acid
hue and therefore
the
The
were prepared.
more hypsochromic
Me
2R1
Re
from
than
the
R
N/
/
H
H
OH
OH
OH OH
(82)
pyrrole
In
indoles
In
Their
absorption
croconic
acid
croconiums.
the
same year
"complexing"
by
the
late
with
croconic
blue"
(84)11,79.
Fatiadi
to
acid
form
obtain
name implies
As the
red-blue
to
malononitrile
"croconic
and
violet"(83)
violet
croconate
identify
products".
condensed
successfully
"croconate
much broader.
also
were
as a reagent
was used
them to
with
1970's
peaks
acid
an intense
is
200
CN
0
'ý.
CN
CN
NC
."0
0.
2K+
2K{
C
CN
CN
heating
colour
the
malononitrile
600nm
absorbing
dipotassium
in
(Emax=55,000)
CN
(84)
(83)
violet
CN
NC
aqueous
in
at
It
533nm (Emax=100,000).
croconate
solution.
aqueous
with
the
appropriate
Croconic
solution
and it
acid
is
blue
is
by
prepared
quantity
absorbs
prepared
of
at
by the
42
action
of
malononitrile
but
solution
treatment
to
necessary
acetone
idealised
the
Croconic
salt.
the
with
than
developed
previously
a hot
A...
with
aqueous
in methanol
methoxide
solutions
the
for
is
blue
acid
is
475-480nm
at
dyes
(81),
This
additional
by PMO theory.
the
croconium
pyrrole
squaryliums.
130nm can be explained
about
in
again,
very
in
alcohol.
earlier
bathochromic
potassium
red
or
acid,
dipotassium
giving
As mentioned
more
with
the
obtain
solvatochromic,
anhydrous
on croconic
squarylium
croconiums
red
(68)
(85),
are
of
as
to
applicable
that
except
are
shift
The same arguments
system
configuration
the
in
(85)
there
oCH = CH -C=C-C=
CH -
CH = N'
00
(85)
two
are
just
carbonyl
one in
the
is
charge
instead
dye
croconium
development
croconic
acid
be partly
rather
it
for
the
will
However,
if
until
evolve
react
such
with.
of
For
simple
condensations
forming
the
to
than
selective
the
rapidlye".
attributable
a 3-hydroxy-N,
condenses
to
was not
fact
This
late
that
croconic
is
N-dialkyaniline
is
a carbon-carbon
bond
used
at
acid
currently
with
squaric
with
readily
that
regards
with
N, N-dialkylarylamines
occur
are
1980's
there
instance,
trione
dyes
early
acid
squaric
of
negative
ring
croconium
it
condensation
whereas
acid,
readily
more
the
Hence,
counterparts.
began
the
a 5-membered
squarylium
that
surprising
nucleophiles
no method
their
instead
positions
Additionally
over
dione.
ring
chemistry
apparently
acid.
than
must
(68).
system
by delocalisation
a 4-membered
rather
two unstarred
sharing
squarylium
stabilised
of
is
It
the
the
bathochromic
more
is
groups
the
the
croconic
3-position
to
43
the
of
eck. Fischer's
enamines,
nucleophile,
to
acid
Croconic
arylamine.
at
form
Several
base.
which
Table
9:
Near-infrared
these
illustrate
the
two
to
appears
readily
classes
react
with
of
croconic
with
dyes.
dyes were recently
croconium
to react
also
from
else
bathochromic
suitably
9,
appears
Apart
little
present
Table
acid
general
absorbing
by Matsuoka
reported
characteristics
et a181,
the
of
dyes8'
croconium
x
Xý
Y
IY
-ýý+
Ný
0
R
R
(86)
Structure
x
A
R
Y
..
/nm
/1mo1-'cm-'
cm
CH3CN
CH2C12
CH3CN
(86a)
CH=CH
H
Et
832
850
222,000
(86b)
CMe2
Benzo
Me
791
804
108,000
Se
H
Et
789
804
200,000
S
H
Et
771
784
223,000
Me
764
775
97,000
(86c)
(86d)
CMe2
(86e)
chromophore.
extinction
exhibited
state
these
the
has
dyes
polar
All
H
the
solvent,
three
thus
structure
carbonyl
also
absorbing
near-infrared
The dyes
band widths.
due to
solvatochromism
a more polar
have
were
and narrow
coefficients
negative
dyes
than
the
groups
that
aiding
the
the
that
fact
excited
ground
state
high
also
the
ground
In
state3.
can strongly
very
with
interact
stability.
addition
with
44
1.4
METAL COMPLEX DYES
1.4.1
In
The Phthalocyanines
1928 iron
product
if
the
pigment
[A
in
the
manufacture
iron
central
of
M=Fe) was synthesised
phthalimide.
ie.
(vapour
copper
phase)]
ýý
It
as a by-
was soon
by copper
atom was replaced
was obtained,
mix=678nm
(87;
phthalocyanine
an improved
(87;
phthalocyanine
that
realised
blue
M=Cu),
.
1
1)
rv
ý/ý
r
N`
N_
N
2'
\
Mme.
N
H
i
N
N-
J
ýN
ý\/
ý\/
ýN
(87)
(88)
Phthalocyanines
classes
of
attention
various
are
one of
known.
chromogen
as potential
Bathochromic
means,
the
most
As such,
near-infrared
stable
they
and tinctorially
have
received
strong
much
absorbers".
can be induced
shifts
into
the
by
phthalocyanines
namely,
in
a.
polymorphism
b.
the
use
c.
the
incorporation
of
`1
the
solid
different
state,
complexing
metals,
donor
of electron
into
substituents
the system
and,
d.
benzannelation.
A number
of
phthalocyanines
are
known
phthalocyanine
exists
in
and
the
greener,
forms
polymorphic
more
of
and used
two major
stable
B-form.
both
and metal-free
metallised
commercially.
polymorphic
The x-form
For
forms,
of
example,
the
the
blue
metal
copper
a-form
free
45
(88)
phthalocyanine
chemist's
it
intensely
The use
of
on the
10:
besides
from
possessing
the
infrared
dye
ca.
680nm,
a profound
effect
a peak
at
800nm.
at
different
spectral
interesting
particularly
because,
viewpoint
absorbs
Table
is
central
properties
metal
the
of
(87)
Phthalocyanines
atoms84-g6
can have
atoms
(Table
phthalocyanines
different
containing
Amx/nm
10).
Thus
central
metal
M
A
Structure
M
(87a) 934
Mg
675
(87g)84
Cu
678
(87b)84
A1C1
680
(87h)84
Sn
672
(87c)64
SnC12
680
(87i)85
Structure
m. x/nm
Si(OSi(n-CGH1
668
3)3)2
(87d)84
Fe
658
(87j)86
Pb
790
(87e)ß`
Co
672
(87k)86
Ti
720
Ni
671
B°
(87f)
(87a)
structures
and titanium
have
molybdenum
to
indium
(90)
the
that
dyes
based
appear
the
to
zirconium
such
phthalocyanines,
have
but
greatest
attracted
with
the
and
in
skeleton
phthalocyanine
and pigments87,
in
maxima
the
of
region
and (87k)
Dyes (87j)
example
into
red-shifts
into
maximum absorption
/ý max
is
900
is
considered
Table
10].
"9O
is
displaced
donor
systems.
phthalocyanine
(91)
(87j),
[structure
electron
positioned
suitably
of
phthalocyanine
790nm
for
red
is
it
the
(89)
as
and
interest
as
absorbers"-".
The use
lead
coloured
and vanadyl
chloride
infrared
the
been
the
show absorption
respectively
incorporated
highly
obtain
and greens.
metals,
in
intensely
absorb
blues
atoms
respectively,
induce
all
Many other
near-infrared.
order
-
and so produce
spectrum
lead
(87i)
to
For
X=H
where
However
groups
if
X is
850nm and if
can also
example,
then
the
if
the
A....
N, N-dibuty1amino
X is
morpholino
is
46
x^
ý.
1
N
NN
/
\N
Iw_.
CI
N/
N
,
N
VO
N
-Nto
x\x
NH2
N
lýN
x/x
xx
xx
X=
Am.x
EtS
A
830nm
=
mix
(89)
762nm
=
(90)
X
N
\N
'/'
Pb
X
(91)
the
If
sixteen
substituted
peripheral
4-methylthiophenol
with
&
[CuPc -E- S -.
Me), 6]
162,000
coefficient
of
that
phthalocyanine
copper
besides
inducing
system,
the
the
dye's
Extending
in
in
positions
then
at
absorbs
shift
4-methylthiophenol
groups
only
to
soluble
longer
have
phthalocyanine
also
an extinction
when it
in
is
considered
sulphuric
wavelength
significantly
solubility.
the
conjugation
of
the
phthalocyanines
are
dye
resulting
Thus,
is
itself
the
770nm with
chloroform'.
an appreciable
copper
by linear
into
acid,
the
enhanced
47
benzannelation
induces
also
a bathochromic
naphtha 1ocyanine
dye (92a)
104nm°5 relative
to the benzene
The
shift.
at 772nm, a red shift
absorbs
((87i),
analogue
of some
10].
Table
/ý
/1
In
./
)4
60
1/
N
1,1"
(a)
M=
Si(OSi(n-C6H,
(b)
M=
Zn
3)3)2
\\
-I
(92)
Non-linear
these
dyes
example,
benzannelation
to
(93)
longer
also
wavelengths,
absorbs
at
displaces
though
710nm whereas
the
to
absorption
a lesser
(92b)
maxima of
degree.
absorbs
For
760nm92.
at
i
1
ý1n
R=
n-CeH
N=
N
/.
(93)
The phthalocyanine
all
round
as such
stability
are
marketed
and naphthalocyanine
of
the
currently
commercially.
known
Their
infrared
dyes
infrared
dye classes,
uses
include
have
optical
the
best
and
data
48
storage
media,
generation
security
printing
Consequently
material.
work
in
inks,
readable
and machine
this
area
is
and charge
currently
very
active93.
1.4.2
Metal
Complexes
1,2-Dithoiols
the
of
Dithiolenes
dithiolates,
or
and Related
(94),
eg.
Compounds
were
in
intensively
studied
R/SH
LI
SH
(94)
the
mid
1930's
complexed
with
complexes
of
as chelating
the
agents94.
zinc,
mercury,
Thus,
and cadmium
(94;
R=C1 or me) could
to
cations
give
be
spirocyclic
(95).
type
R
S,
`
I
M/S
SR
R=
Me,
Cl
M=
Hg,
Zn,
Cd
(95)
Interest
1940's
the
reagent
It
in
type
this
and early
of
1950's
continued
complex
work
and,
on toluene-3,4-diol
for
example,
as an analytical
described95.
was
was only
in
1962 that
the
cs/
first
S\ /s
Ni
(96)
infrared
during
absorbing
nickel
49
dithiolene
complex
reaction
to
Ni(CO)4
of
The complex
nickel
prepared
certain
have
been
ester
form
OH
of
by the
yields
(Scheme
previously
be
only
reaction
P. S, o in
and then
complexes
than
complexes
with
dithiobenzoin
0
11
of
of
alkynes
this
type
dioxane
adding
form
to
nickel
12)97.
Dioxane
C
Ar-CH-
low
an attempt
as catalysts".
initially
could
benzoin
dithiolene
the
metals
More recently,
by refluxing
prepared
to
in
in
wavelength
complexes
sulphides.
thiophosphoric
acetate
These
some difficulty
metal
transition
a much longer
at
from the
product
diphenylacetylene,
with
using
absorbed
complexes.
with
with
the
(96)
as an unexpected
and sulphur
thioaromatics
synthesise
known
was obtained
Ar
+ P, S, o
ester
-Bodithiophosphoric
Ni(OAc)2
Ar
Ar
/s
cs/
Ni
f%
Ar
Ar
Scheme 12
The complexes
This
is
(11)68.
is
effect
strongly
exemplified
Evidently
a bathochromic
extinction
of
region
it
nature
exceptionally
shift
the
spectrum.
dependent
by the
phenyl
and acceptor
groups
the
Electron
groups
As this
absorption
the
absorption
is
n --f n
effects
extend
same time
donor
a hypsochromic
data
the
contained
conjugation
noticeably
groups
effect.
in
in
to
stable
are
in
on substituent
spectroscopic
and at
coefficient.
air
show an intense
All
acids.
non-oxidising
infrared
are
and most
stable
near-
the
in
ligand.
Table
which
increases
effects
the
have a bathochromic
50
Table
11:
Spectroscopic
1'2-dithiolene
for
data
some typical
examples
of
complexes"
R
g\
`
Ni
S/
R
'S
R
(97)
Structure
R
nmaxý
/lmo1-Icm-,
Em.
(x10-`)
(97a)
(97b)
-CH3
714(101'
2.82
-CF3
714(°'
1.22
\
866(°'
855('
3.01
3.02
(97c)
/
(97d)
CF3
832
2.99
(97e)
OMe
894(b'
2.80
(a)
(b)
The
central
nature
instead
workers
reacting
/
-
in
in
measured
measured
A
of
max
metal
the
of
of
atoms
and the
required
NH2
For
demonstrated
as recently
dyes
of
example,
the
(98)
phenylenediamine
i.
K or
KOH in
with
R1
NH2
ii.
NiC12.6H20
et
by,
Scheme 13
a19B.
firstly,
an ethanolic
/N3.
NH H2
(99)
(98)
also
by the
can be used
NH2HN
EtOH
RI
but
by Matsuoka
(99)
by the
only
nitrogen
formula
general
not
R (97),
groups
substituent
atoms.
chelating
synthesised
influenced
be
can
complexes
such
sulphur
the
CHC13
CH2C12
These
51
solution
of
potassium
addition
of
nickel
effect
been
storage
to
hexahydrate
(Scheme
photofading
incorporated
to
media,
13).
Nickel
dithiolenes
are
dithiolenes
followed
dissolved
The dyes
be singlet
in
this
of
oxygen
dyes99"100.
cyanine-dye
by
to
ethanol
type
are
the
of
quenchers
Thus,
such
containing
photofading
also
complexes
data
optical
dye which
cyanine
and
is
prone
oxygen'01.
have
find
found
also
use as Q-switch
by Eastman-Kodak
marketed
also
to
of
into
retard
by singlet
(100b)
known
are
the
attack
and
hydroxide
potassium
chloride
dithiolenes
inhibit
have
or
absorbing.
Nickel
hence
(II)
formation
complex
infrared
ethoxide
use
in
laser
for
this
recording
dyes,
1,2-nickel
purpose.
materials,
R2N
(100a)
eg.
having
good
NR2
I/
S\
g`
Ni
I/
(a)
(b)
R=
R=
Me
Et
(100)
sensitivity,
high
resistance.
I. C. I.
(sulphonated)
complexes
1.4.3
Metal
is
Complex
for
acceptor
that
derivatives
are
for
to
bathochromic
practical
ink
in
Work on
applications.
Indophenol-type
metals
certain
at
the
possess
laser-diode
Ligands
donor-
indophenol
acceptor
and show increased
generally
use
soluble
active".
that
recently
and good degradation
and water
Heterocyclic
complexed
The dyes
coefficients103.
properties
very
very
Dyes with
ratio
organic
specialised
currently
has been discovered
It
signal-to-noise
manufacture
versions
these
dyes
readout
produce
extinction
good physical
optical
group
data
and chemical
storage.
52
One such group
(103)
of dyes is
may be prepared
which
a 4-dialkylaminoaniline
Ho
derived
from the
by coupling
hydrochloride
7
(102)
in
(101)
the
R'
an
NRz
/
(a)
(b)
(102)
of
with
N\/
N`
NR2
HCl
(101)
presence
0=
`
H2N
derivative
8-hydroxyquinoline
10)
N\
indoaniline
R=
R=
Et,
Me,
R'=
R'=
Me
H
(103)
Scheme 14
oxidising
the
(Scheme
agent
complexes
obtained
14).
are
When complexed
of
the
to
the
appropriate
formula
generalised
0
-:
(104).
metal,
Spectral
NR2
M; ==--
X2
n
(104)
data
for
12:
Table
these
some of
Spectral
formula
complexes
properties
(104)10°
of
are
in
summarised
indophenol-type
Table
dyes
of
12104.
the
It
general
Amax/
Structure
M
R
R'
X
n
º(EtOH)
cm. x/lmol-'cm''
(104a)
Cu
Et
Me
C104
2
776
144,000
(104b)
Cu
Et
Me
C104
1
721
60,000
(104c)
Ni
Et
Me
C104
2
775
118,000
(104d)
Ni
Et
Me
C104
1
742
72,000
(104e)
Cu
Me
H
C104
2
772
144,000
(104f)
Cu
Me
H
C104
1
722
69,000
(104g)
Ni
Me
H
C104
2
742
75,000
(104h)
Ni
Me
H
C104
1
728
60,000
(a)
- measured
in
ethanol
( am)
53
can
be seen
with
higher
dyes.
that
bidentate
extinction
Additionally
complexes
are
Ligands
Ni2ý,
the
the
the
across
than
bidentate
copper
equivalent
type
(105a)
the
is
absorb
and
monodentate
at
longer
when the monodentate
true
have
atoms marked * and **,
been
also
to give
g
**
wavelengths
equivalent
dyes
(105b)
and
longer
at
dyes but
nickel
the reverse
considered
of
absorb
coefficients
the
than
wavelengths
complexes
to
complexed
complex dyes that
R1
NR2
NN
*N
(a)
(b)
R=
R=
Et,
Me,
R'=
R'=
Me
H
(105)
absorbed
at
ligands
of
solution
ethanolic
a refluxing
These
prepared,
were
(106)
Scheme 15 by adding
to
according
yields,
to
782 - 838nm105.
(103).
in
about
hydroxide
and potassium
thiol
the
If
50%
(106)
is
HS
R1
H2N
S
R1
(106)
NR2
0N
\/\
NRW
N
KOH
Na
/N
\\
(105)
(103)
Scheme 15
replaced
are
by o-aminophenol
When complexed
afforded.
(107a)
has
then
a
Amu
of
797nm,
ligands
to
with
Nie'
of
in
the
general
ethanol,
an extinction
the
formula
(107)
complex
of
coefficient
of
54
38,9001mo
746nm in
1-1cm-1.
the
Similarly
complex
nickel
dimethylformamide/chloroform'o6.
p
R1
)/-
7N
NR2
: ---
N` ýý
(a)
R=
Et,
R'=
(b)
R=
Me,
R'=
(107)
Me
H
of
(107b)
absorbed
at
55
2.
2.1
APPROACHES TO HIGHLY
As noted
class
over
(108),
in
number,
commercial
use
1.3.3)
(Section
and have
been
infrared
and some metal
infrared
azo dyes
though
even
The only
many years.
(44),
BATHOCHROMIC AZO DYES
introduction,
the
few
surprisingly
in
in
AND DISCUSSION
RESULTS
are
investigated
to
examples
in
date
the
X
N=
A
N
\
S
/
include
R
N\
R'
Y
NC
CN
I
C-
A=C=
or
NC
ýH-
or
N
CN
CN
CN
I
CHS0
0
(108)
CI
/S`
02N
NEt2
N -N
N-N
NHCOCH3
(44)
most
great
complexes.
cl
azo dyes
are
numerous
detail
types
56
These
dyes
extremely
because
a common donor-acceptor
donor
group,
groups
[A in
powerful
powerful
rings
have
acceptor
in
(108)
their
of
The effect
can be seen
(44)
and
also
readily
of
In particular
Table
13:
it
The effect
(108)].
a useful
n-electron
of
of
the
the
can be seen,
of
donor
electron
02N
strength
with
and thiophene
maxima
effect
of
dyes
13, that
azo dyes
of
in
Table
an acylamino
on monoazo
dyes6B
NR
`/N.;.
(109)
Strucure
A
R
(109a)
(109b)
max/
(CH2C12
F-n%aLic/lM01-'CM-'
(CH2C12)
NEt2
498
35,400
NEt2
522
48,850
508
37,500
523
53,900
543
48,550
NHCOCH3
CH3
JNHEt
(109c)
NHCOCH3
NPr2
(109d)
NHCOCH3
CH3
CH3
CH3
N
(109e)
Et
NHCOCH3
an
and very
systems.
series
from Table
(108)]
bathochromic
absorption
simple
system
NHAc in
The thiazole
contribute
strength
by consideration
1368.
[X = OCH3j Y=
polarisable
donor
chromophoric
57
group
to
ortho
additional
Structure
nitrogen
nitrogen
system
held
azo dyes
particular
study
less
with
the
a ring
of
shift.
powerful
donor
hydrogen
of
was made
in
(111),
derivatives
ethylene
(113).
R R'
VýH
Hý
RN
N/
NN
1
(111)
(110)
R
CHN
R2N
/
,4*--Z
II
NR2
-110
1.
The spectroscopic
would
2.1.2
the
facilitate
Azo Dyes Based
these
influence
of
design
new infrared
of
on Perimidine
groups
was examined
azo dye
and Dihydroperimidine
as this
systems.
Electron
Systems
Donor
The perimidines
potential
CH
1
(113)
)
(2
to
form
(114)
and dihydroperimidines
azo dyes
by direct
diazo
the
n-electron
groups,
perimidines
and Michler's
of
electron
an examination
electron
(110),
terms
electrons
the
bathochromic
dyes,
the
pair
with
in
due to
fusing
of
The lone
new infrared
(112)
both
conjugation
dihydroperimidines
benzindole
substituted
in
molecule
planarity
effect
system.
common,
the
of
can be explained
the
shows
a significant
the
of
half
and enhanced
more rigidly
and so give
As part
in
donor
the
This
donation
(109e)
atom
are
in
shift.
+M electron
bonding.
of
linkage
azo
a bathochromic
causes
donor
the
(115)
coupling,
have
the
and they
58
R
R
R'
x
H`
RNý
ýH
NN
N'
ýý
ýý/
(114)
themselves
provide
Although
powerful
systems
"'
reviews"',
reports
the
perimidine
for
example
be few and far
to
is
have
the
lemon
been well
on perimidines
and
in
potential
releasing
of
dyes,
cyanine-type
unsymmetrical
yellow
in
covered
between.
electron
and synthesised
which
residues.
(115)
and
based
acknowledged
system
(116)
(114)
dyes
of
appear
1955 Jeffreys
donor
electron
types
of
dihydroperimidines
In
(115)
colour".
Et
S
I
CH
/>
14
NN
\/
Et
(116)
In
(117b)
the
same paper
were
benzene
the
These
described.
red
dyes
absorbed
Me
dyes
at
(117a)
ca.
absorbing
solvatochromism,
negative
and exhibited
based
dihydroperimidine
and
515nm in
at
about
0N
C
N/A
CH=CH
--C
N
Me
(117a)
(117b)
508nm in
methanol.
A=
A=
2-ethylthiothiazol-5-one
3-methyl-2-thiothiazolid-5-one
Negative
solvatochromism
only
occurs
in
dyes
that
59
have
highly
polarised
dihydroperimidine
derived
from
large
+M effect
the
of
apparent.
and Abou-Zeid
synthesised
itself
perimidine
the
Thus
states.
is
system
1972 Allum
In
ground
the
of
several
general
dyes
monoazo
formula
(118) 10.
These
H
RN=N
N
N
(R = Cl,
OH, Me)
(118)
dyes
dyed
then
were
No reference
assessed.
lightfastness
and their
on nylon
to
structural
properties
characterisation
of
the
dyes
was
made.
In
Sudan
1977 Miller,
Black
B"',
Franz
and Preiss
a commercially
black
ball
Black
B contained
point
pen
that
inks"'.
in
used
that
18 fractions
of
a minimum
is
transpired
It
characterisation
dye derived
available
dihydro-2,2-dimethyl-lH-perimidine
the
undertook
the
the
that
and
from
of
2,2-
manufacture
Sudan
commercial
the
two
of
main
R2
H
1
N
Me
`/
Me/ý(`
N
H
X=
N=N
-NON-(/
(119a)
R2 = H, R'
(119b)
R'
=X
R2
H,
=X
=
(97.5%)
fractions
`/
(119b)
respectively,
disazo
dye
it
is
were
in
perhaps
the
para
a ratio
not
and ortho
of
3: 1.
surprising
derivatives
As Sudan Black
that
(119a)
B is
so many fractions
and
a complex
were
60
present.
the
In
present
study,
and perimidine
systems
simple
dyes.
monoazo
characteristics
systematic
have
In
these
of
been
this
variation
of
investigated
way the
for
colour
donor
electron
the dihydroperimidine
representative
and constitution
groups
could
in
be studied
detail.
2.1.2.1
Synthesis
The two
of
perimidines
Intermediates
used
in
and Dyes
this
work
were
(120a)
(120b).
and
Me
Rý
NýN
nr
(120a)
R=H
(120b)
R=
These
Et
prepared
were
as shown
in
Scheme 16.
The success
of
the
first
Me
HH
\N`N
CH3000-
NH2
NH2
I
I
(CH3CO)20
/ Heat
(121)
i.
ii.
Me
Me
H
Et w
N
ýN
\N
N
sulphonate
Ethyl-p-toluene
Fuse/1601C/1h
(120a)
(120b)
Scheme 16
H2O
NH3(aq)
61
stage
this
of
sequence
1,8-diaminonaphthalene
recrystallisation
free
from
(120a)
perimidine
by
purification
methylperimidine
this
which
has
also
ligroin
(b. p.
(120b)
as pale
crystals.
only
It
solvent
reported
was hoped
the
of
aldehydes
of
that
by
acid
and subsequent
1-ethyl-2The last
stage
of
(120a),
alkylation.
in
" 3.
the
of
N-alkylating
way of
to
resistant
condensation
solubility
yellow
effective
Fusion
the
of
was purified
sulphonate
gave
1,8-diaminonaphthalene107"
attempted.
100-120°C).
ethyl-2-toluene
purity
material
chromatography
been
by the
prepared
The commercial
on the
column
was surprisingly
It
(121).
with
was the
synthesis
much dependent
was very
literature
that
can be
perimidines
with
Accordingly
the
n-heptyl
any resultant
dyes.
the
synthesis
chain
would
However,
(122)
of
aid
the
although
was
organic
various
(CH2)6CH3
H1
ý\N
N
(122)
conditions
use
(including,
employed
were
of
a variety
of
solvents
desired
product
could
not
that
were
prepared
dihydroperimidines
Schemes
17 and
for
cases,
After
18.
amount
addition
and azeotropic
as well
are
acid
removal
of
the
catalysis,
water)
in
were
1,8-diaminonaphthalene
of
ethanol
of
a catalytic
to
effect
amount
14.
Table
by one of
method,
that
intermediates
as related
listed
prepared
The first
ketones
those
recrystallised
minimum
were
example,
the
be isolated.
The dihydroperimidines,
(125)
for
liquid
at
of
as shown in
was utilised,
in
room temperature.
was dissolved
solution
in
and the
sulphuric
and
The
two routes
Scheme 17,
(124)
acid
water
ketone
the
most
Thus
with
added.
solution
the
62
Table
14:
intermediates
Dihydroperimidine
synthesis
of monoazo dyes
R
in
prepared
this
work
for
Ri
HX
ýN
N
ýH
I
(123)
IRI
Structure
R'
(123a)
-CH3
-CH2CH(CH3)2
(123b)
-CH3
-CH(CH3)2
(123c)
-CH3
-(CH2)4CH3
(123d)
-CH2CH3
-(CH2)4CH3
(123e)
-CH2CH3
-CH2CH3
(123f)
-CH2CH3
-CH2CH(CH3)CH2CH3
(123g)
-CH3
-CH2CH2000(CH2)3CH3
0
(123h)
-CH3
(1231)
-CO
`/
OEt
ýO
Me
IH
H
ýNýýN/
NN
`ý
(124)
(125)
`
63
was heated
with
60°C for
at
aqueous
30 minutes.
hydroxide
sodium
Cooling
generally
followed
afforded
by neutralisation
a white
precipitate
R
Y",
H
NH2
NH2
i.
/
RCOR'
H2SO4 /
ii.
/
EtOH
R'
/H
, IN
NN
H2O
Heat
NaOH(aq)
Scheme 17
of
the
or
acetyl
this
dihydroperimidine.
biphenyl
case,
sulphuric
For
ketones,
solid
Scheme 18 was followed.
a catalytic
acid
the
amount
was used
of
for
Water
was not
2-toluene-sulphonic
and higher
temperatures
example
acid
than
rather
and longer
reaction
R'
Hý
N H2
in
present
R
X
NH2
benzil
/H
NN
/
RCOR'
I
p-toluene
/
EtOH
Reflux
sulphonic
acid
Scheme 18
times
were
that
was apparent
isolated
Where derivatives
necessary.
the
method
Scheme 18 leads
made by both
to
purer,
it
methods
more easily
products.
The dihydroperimidine
(124)
heating
1,8-diaminonaphthalene
4 hours
and was deposited
The fused
ring
of
cyclisation
heating
in
were
(123g)
The structure
spectroscopy.
with
diethyl
malonate
as a pale
yellow
precipitate
(125)
was obtained
dihydroperimidine
dihydroperimidine
in
of
ethanol
(125)
Whereas
with
(123g),
uncyclised
Scheme 19,
at
150°C for
via
the
Scheme 20,
acid
by microanalysis
derivative
by
on cooling.
as shown in
p-toluene-sulphonic
was confirmed
the
as in
was synthesised
(123g)
by
as catalyst.
and by infrared
exhibited
a
64
NH2
NH2
I
OEt
+ H5C2000CH2COOC2H5
O
HN
N/H
i.
150°C
ii.
Cool
/
4hours
/ Filter
(124)
Scheme 19
U
O
Me
Me
HH
HO
ýN
NN
EtOH / p-toluene
sulphonic
N
acid
00.
-
f
12 hours
reflux
(125)
Scheme 20
carbonyl
saturated
absorption
frequency
of
the
ester)
at
The reaction
1714cm-'
benzil
to
1,8-diaminonaphthalene
particularly
typical
with
one equivalent
form
the
at
variance
ý 1ý
H
H
\\
/r
ring
N/\
N\
H
/N
H
(126)
bonded
corresponding
lactam.
of
dihydroperimidine
is
a hydrogen
showed
a 5-membered
of
as it
interesting
of
(125)
derivative
cyclised
1689cm-',
of
(characteristic
with
(1231)
literature
is
claims.
65
The compound
its
i. r.
spectrum
for
expected
bonding.
In
reaction
gave
error
the
gave
refluxing
ketone
with
European
Patent
0 071 197A1114
a product
of
from
(as
used
in
is
used
1,8-diaminonaphthalene
precipitates
from
not
to
benzil.
to
The two
(123a)
-
the
in
(124)
the
4-nitrobenzene
From the
Black
to
of
B it
acetic
In
the
acid
at
0-
that
For
thus
of
least,
at
it
is
to
chemical
dihydroperimidines
as coupling
the
convenience
giving
ortho
and para
the
solution
However,
coupling
in
of
and indeed
their
evaluation
diazonium
ions
this
within
was carried
work
acid
into
of
coupling
in
t. l. c.
mixture
until
a mixture
of
in
to
this
ice
the
water
with
this
analysis
the
of
the
and the
and sodium
nitrite
dihydroperimidine
the
hot,
chloride.
minimum
was added
standard
an
dissolved,
4-nitrobenzenediazonium
reactions,
and to
by the
out
was heated
4-nitroaniline
a solution
preliminary
"2
case.
was poured
give
effect
5°C.
known
Thus
was dissolved
perimidine
to
is
: hydrochloric
to
an excess
14.
examined
and Preiss
4-nitroaniline
of
solution
solution
Franz
be the
method.
acid
clear
Pfüller,
can be complex
Diazotisation
suspension
ethanol
and the
then
was used,
in
derivatives.
work
proved
azo dyes.
in
(123i)
Table
(120b)
of
if
even
identical
showed
were
is
patent
1,8-diaminonaphthalene
in
and
ion
in
of
(125)
synthesis
dihydroperimidines
also
and
diazonium
4-nitrophenylazo
Thus,
this
Firstly,
dihydroperimidine
(123i)
(120a)
the
method)
solution.
product
That
the
the
that
was claimed
observations.
patent
as
hydrogen
additional
dihydroperimidines
other
(123i),
(126).
two molecules
perimidines
components
Sudan
hot
condense
Secondly
reactivity
of
the
two
it
and
1680cm-1,
at
some intramolecular
structure
(123i)
structure
frequency
a phenyl
ethanol
possible
for
microanalysis
a C=0 stretching
showed
be deduced
can
correct
amount
of
diazonium
coupling
products
or
acetic
solution
from
66
such reactions
isolation
and purification
A study
the
showed the presence
the
of
of several
the
of
pH dependence
major
of
the
diazo
It
coupling
dyes
that,
was concluded
making
impractical.
components
2,2-dihydro-2,2-dimethyl-lH-perimidine
undertaken"5.
products,
reaction
(127)
regardless
of
and
giving
(128)
the
pH,
was
coupling
Me Me
H**-.
H
NXN
NO2
Me Me
H`
1
/H
NN
I
II
ý
N
.N
i
NO2
(127)
reaction
in
all
was always
3-7.
It
the
may be that
dihydroperimidine
ring
and
will
(128)
to
other
at
This
N-coupled
formed
least
pH values
hydrolysed
will
also
from
were
below
is
from
products
in
obtained
3 and above
back
couple
Apart
different
six
couplings
azo dye products.
and dyes
be the
at
cleanest
system
1,8-diaminonaphthalene.
leading
forming
complex,
However
cases.
range
(128)
7 the
diazonium
with
the
the
desired
dyes
another
(129).
NO2
Me Me
N
N'ý
ýý 11
ý
'*,
N
(129)
The influence
of
solvent
on the
coupling
pH
to
1,8-diaminonaphthalene
derivative
the
reaction
was then
ion
(127)
product
67
examined,
and this
gave
dimethylformamide
nitroaniline.
In
mixtures
were
Para
and
and to
acetone
were
isolate
15:
major
azo dyes
Structures
synthesised
of
in
the
only,
component,
prepared
are
acetic
case
It
the ortho
possible
and
to
chromatography
in
Table
The
15.
(X = 4-02NC6H4N2)
R'
R
(a)
complex
mass spectrometry.
summarised
dyes
acid
was then
by column
or
4-
of
presumably
on t. l. c.
4-nitrophenylazo
Structure
R
fractions
detectable
each
and glacial
However,
dihydroperimidine
the
of diazotised
a solution
them by microanalysis
the
of
of
obtained.
characterise
structures
Table
the
two major
derivatives
separate
with
case
Thus
results.
was treated
again
dimethylformamide
promising
-CH3
-CH2CH(CH3)2
-CH3
-CH(CH3)2
(c)
-CH3
-(CH2)4CH3
(d)
-CH2CH3
-(CH2)QCH3
(e)
-CH2CH3
-CH2CH3
(f)
-CH2CH3
-CH2CH(CH3)CH2CH3
(g)
-CH3
-CH2CH2000(CH2)3CH3
(h)
\/
R'
(b)
N
(130)
-CH3
-CO"O
R R'
H\
/H
NN
(a)
-CH3
-CH2CH(CH3)2
(b)
-CH3
-CH(CH3)2
(c)
-CH3
-(CH2)4CH3
(d)
-CH2CH3
-(CH2)4CH3
(e)
-CH2CH3
-CH2CH3
(f)
-CH2CH3
-CH2CH(CH3)CH2CH3
x
(131)
68
Table
15:
continued
R'
R
Structure
(g)
-CH3
(h)
-CH2CH2COO(CH2)3CH3
-CH3
/
(i)
(131)
-CO
H3
H0
NN
I
(132)
x
OEt
0
IN
H
NN
X
(133)
Me
/R
NN
(a)
-H
(b)
-CH2CH3
(a)
-H
(b)
-CH2CH3
(134)
Me
J
NN
X
(135)
69
The isomeric
dyes
(120a)
perimidine
isolate.
It
N-coupling
(134a)
that
appeared
to
hindrance
(134a)
in
the
With
both
the
all
(123)
isomer
isomer.
This
reflects
the
difficult
to
the
is
the
example,
the
full
Thus
unalkylated
synthesis
NH group
may reflect
(132)
(133)
and
isomeric
coupled
be separated
and
to
more prone
-NH groups
greater
of
steric
characterisation
of
couplers
than
Rr on silica
hydrogen
in
hydroxy
bonding
in
for
and affinity
gave
was found
It
chromatographically,
higher
polarity
the
all
dyes.
known phenomenon
a well
their
for
coupling.
dyes
intramolecular
reduces
than,
This
an appreciably
is
from
possible.
of
could
showing
which
was not
and para
these
ion
ortho
exception
ortho
cases
to
most
derived
non-alkylated
(123).
(135a)
and
the
the
diazonium
the
dihydroperimidines
the
by far
proved
(135a)
and
the
the
ortho
the
para
azo dyes
the
in
that
and
isomers
ortho
absorbent
(136)
: cf.
(137).
and
Ar
Ar
ýý
NýN
ýý
H
ýH"ýN
ýN
0N
X
(137)
(136)
that
Confirmation
higher
the
of
to
the
protons
the
both
the
hydrogen
were
NH proton
dyes
the
dye
ortho
broader
a
and
6=5.0
[(130h)
examples
representative
spectrum
by
made
was
Rf value
bonded
para
to
position
For
6=4.7
the
showed
the
and 6=5.4,
deshielding
and multiplicities
bonded
latter
the
the
NH
to
corresponding
4-nitrophenylazo
of
NH at
corresponding
(131h)
derivative
the
'H-n. m. r.
the
6=11.3
at
had
of
a non-hydrogen
proton
para
coupled
Thus
that
product
spectroscopy
(131h)).
deshielded
NH.
at
ortho
'H-n. m. r.
and
(130h)
strongly
located
the
indeed
was
it
aromatic
group.
For
protons
70
agreed
the
with
the
In
formed
as shown
para
were
confirmed
the
that
could
be attributed
as
in
shown
11,
(133a).
in
spectra
were
and the
absence
case
(132)
the
however,
was much more complex
to
the
structure
6 ca.
structures
of
had occurred.
intramolecularly
show a strongly
Thus
was
suggested
The para
spectroscopy.
at
product
low R= values
preferentially.
NH signal
(133)
one major
and the
m. r.
coupling
of
only
4-nitrophenylazo
overall
para
The spectrum
group
'H-n.
by
deshielded
a strongly
and (133)
had occurred
again
with
confirmed
(132)
chromatographically
coupling
consistent
This
structures.
case of dyes
that
of
assigned
hydrogen
hydrogen
bonded
bonding
to
the
Interestingly
in
NH proton
the
ester
at
6=16.6.
is
OEt
H
H %ý,,
NN
N02
NN`/
(133a)
at
of
the
5).
than
(rather
This
lone
nitrogen
deshielding
in
than
much lower
the
other
dihydroperimidine
may be attributed
pairs
NH proton
into
the
systems,
the
to
strong
i. e.
,
P
co
C --OEt
-OEt
-3
H
/H
N
N
ýý
f
ý/
6=10.8
delocalisation
residue
ester
acrylate
at
did
carbonyl
NH proton
second
it
that
thus
also
71
2.1.2.2:
Light
Absorption
Properties
the
of
Arylazo-
erimidines
and
Dihydroperimidines
The visible
(135)
were
absorption
in
measured
indication
of
absorption
coefficients
and were
of
for
those
characteristics
16 and those
Table
16:
the
of
Spectroscopic
derivatives
para
for
coupled
coupled
data for the ortho
of dihydroperimidines
Molar
spectra.
be pure
dyes
are
in
solutions
by
by t. l. c.
summarised
cm-'
/nm
AA
.,,.
(CH2C12-Tol)
559
558
+1
(130b)
559
559
0
(130c)
558
558
0
(130d)
557
557
0
(130e)
557
556
+1
(130f)
558
557
15,100
+1
(130g)
556
554
14,300
+2
(130h)
561
562
13.800
-1
(130i)
523
523
10,000
(134a)
555
550
(134b)
562
558
those
summarised
dihydroperimidine
donating
substituted
of
in
dyes with
Typically
a
7,500
max
17,
ring
and perimidine
residues.
+5
values
16 and
Tables
0
+4
Amax
the
it
in
17.
Table
(130a)
From a comparison
The
4-nitrophenylazo
and perimidines
Em4Kx/ lmol-'
(CH2C12)
max/nm
(CH2C12)
(Toluene)
an
characterised
analogues
A
Dye
fully
(130)-
so giving
dichloromethane
and shown to
ortho
dyes
on the
polarity
compounds
the
of
4-nitrophenylazo
and toluene,
solvent
mass spectrometry
Table
the
determined
were
only
or
of
dichloromethane
influence
measured
microanalysis
spectral
the
spectra
in
presented
can be seen
systems
the
perimidine
ca.
590nm which
are
13 and
Table
that
the
powerful
residue
gives
are much more
electron
para-
72
Table
17:
Sp ectroscop
of dihydrop
ic data for the para 4-nitrophenylazo
erimidines
and p erimidines
A
Dye
Emax/
msLx/nm
(CH2C12)
(Toluene)
derivatives
lmol-'cm-1
(CH2C12)
(CH2C12-Tol)
(131a)
545
547
(131b)
546
546
0
(131c)
547
547
0
(131d)
546
546
0
(130e)
544
545
(131f)
546
545
15,000
+1
(131g)
509
494
15,100
+15
(131h)
547
548
15,300
-1
(131i)
524
523
9,500
+1
(132)
503
505
33,600
-2
(133)
396
395
50,500
+1
(135a)
590
578
(135b)
596
580
bathochromic
diazo
dyes
wavelengths
behaviour.
wavelengths
(A
545nm).
is
still
also
a powerful
effective
The slightly
as the
perimidine
(135a)
donating
system,
bathochromic
and are
in
derivatives
their
the
at
at
residue
with
character
its
Table
of
the
ortho
colour.
longer
ca.
x
system,
whilst
is
as
13)
additional
The
show
(Äý.
dihydroperimidine
(cf.
in
they
isomers
a
somewhat
violet
absorb
para
the
based.
that
same
only
containing
absorb
interesting
than
that
(134b)
the
probably
thiazole
or
isomers,
ortho
from
are
monoazo,
are
thiophene
are
560nm)
(135b)
and
and
+16
dye derived
monoazo
para
the
apparent
electron
greater
the
Thus
ca.
msx
12,100
(134a)
dyes
The dihydroperimidine
It
not
and are
than
+12
which
analogues
ortho-substituted
different
dyes
the
synthesised
yet
group
nitrophenylazo
shorter
fact
-1
simple
any other
In
species.
blue
only
than
-2
not
conjugation.
73
dihydroperimidine
in
terms
dyes
compared
intramolecular
of
the
with
hydrogen
R
bonding
may be explained
in
as shown
(138).
This
N02
/
Rý
H
isomers
para
I
/H
NN
IIN
(138)
not
only
induces
the
azo
B-nitrogen
This
atom.
dye
greater
and so leads
easily
the
situation
calculations
(see
calculations
do indicate
for
available
shown
in
later).
the
perimidine
for
by more detailed
is
worthy
site
of
greatest
by coupling
formed
on
NH nitrogen
dyes
the
of
the
of
at
this
less
is
MO
that
note
PPP-MO
electron
density
is
position
1-ethyl-2-methylperimidine
The dye
a6
characteristics
it
However,
in
coupling
(139).
for
accounted
that
provides
shift.
observed
is
also
associated
donor-acceptor
general
but
rationalised,
on the
charge
a bathochromic
to
but
planarity
and a 6-
atom,
enhances
The reverse
molecular
the
a
exhibits
site
me
Etw
NN
x
(139)
steric
inherent
value
occurs,
(134b)
Dye
between
clash
the
non-planarity
the
and also
and
is
thus
(133)
as well
duller
also
is
molar
to
contribute
extinction
the
phenylazo
a reduction
coefficient.
as absorbing
than
particularly
group
ethyl
will
and the
isomeric
interesting
at
a shorter
in
the
A
.. x
Band broadening
wavelength
(135b).
and shows
This
residue.
exceptional
dye
also
74
properties,
absorbing
rationalise
such
diazonium
ion
derivative
at very
short
a hypsochromic
(140).
this
If
it
shift
must have N-coupled
395nm).
ca
max
was initially
to form
the
were
(A
wavelengths
the
the
the diazoamine
however,
case
thought
To
then
acid
catalysed
OEt
02
0N
N
NO
N
(140)
cleavage
of
ion
which
test
this,
to
couple
species
should
be trapped
could
phloroglucinol
to
(133)
this
was the
the
previously
by a suitably
ion
species
correct
structure
to
nucleophile
for
the
was confirmed
as this
coloured
be detected,
To
nucleophile.
an intensely
structure
(133)
powerful
as the
give
could
4-nitrobenzenediazonium
the
regenerate
was used
diazonium
the
no coupling
that
this
and it
would
dye.
was concluded
As noted
product.
'H-n. m. r.
by
spectroscopy.
Dye
uncyclised
(132)
absorbs
analogue
about
(131g).
60nm to
shorter
the
Evidently
OBu
0
Me
H ý0
Hie
N
N
Ný
NN
_i
ý,
Ný
N
I
NO2
(132)
than
wavelengths
-M effect
N02
(131g)
However
of
the
the
75
carbonyl
bonded
group
the
reduces
residue,
to
donating
electron
in
turn
shifts
the
E...
value
which
Interestingly
analogue
(131g),
suggesting
enforces
greater
overlap
of
the
n-electron
The two
dihydroperimidine
the
system
isomeric
dyes
2-benzoyl-substituted
capacity
the
for
to
ýsx
in
the
of
(132)
that
(132)
dihydroperimidine
shorter
the
the
NH lone
of
the
chromophore
and
significantly
wavelengths.
than
was much greater
of
(1301)
nitrogen
additional
pair
(131i)
dihydroperimidine
annelation
electrons
[cf.
(1231)
Ph
13 dye
rest
(109e)].
derived
are
also
the
with
Table
which
for
from
exhibit
the
a
COPh
H
Hý
N"'e
N02
COPh
Ph
I
,Ha
NNN
00
O"J
11
N
N
N02
(131i)
(130i)
significant
hypsochromic
shift
dyes
derived
to
compared
those
dihydroperimidines.
and
(131i)
dihydroperimidine
of
effects
of
reduces
electron
by comparison
of
shift
a-position
also
56nm occurs
of
(140).
observed.
the
group
donating
strength
electron
and intensity
of
attached
groups
withdrawing
are
dyes
when a cyano
A reduction
known1'.
well
(141)
(142).
and
group
of
when
2-carbonyl
The hypsochromic
moiety.
intensity
2,2-disubstituted
of
the
an N, N-dialkylaminobenzene
provided
is
from
The presence
evidently
in
and reduction
the
is
to
the
(130i)
of
the
lowering
a-carbon
An example
atom
is
Thus a hypsochromic
introduced
molar
in
extinction
into
the
coefficient
76
CH3
/`N=NN
C2N
CH3
A
mýx(EtOH)
478nm
=
c.,
33,100
=
1mo1-'cm-1
(141)
CH3
02N
N-N
N
CH2CN
A
422nm
=
maxiEtOH)
Emax
26,000
=
Zmo1
1Cm-1
(142)
For
the
majority
coefficients
of
were
dyes
bands,
4:
Fig.
In
half-band
of
widths
UV-visible
in
Tables
low compared
relatively
30,0001mo1-'cm-1).
ca.
listed
125nm,
ca.
spectrum
(130g)
17 the
aminoazo
showed broad
Fig. 4.
eg.
dye
of
to most
dyes
the
addition
16 and
in
Most
extinction
dyes
(Cm
absorption
aminoazobenzene
dichloromethane
1 ý1
.
A
`\
A
"l 1
......................................
ýCiü
On
45)
4ARCIA
aft
Log
P.C-1-l AA
')O
/ nm
wavelength
A-
F.F0
ýlCý
absorbance
dyes
have
half-band
may be attributed
coefficient
area
that
The light
widths
of
is
a true
measure
absorption
ca.
to
of
properties
95nm.
this
extinction
band broadening
absorption
of
The low
the
as it
is
band
intensity.
dyes
were
next
examined
77
theoretically
by carrying
PPP-MO calculations
out
on representative
examples.
As the
systems
their
case
nitrogen
atoms
held
are
rigidly
n-electrons
of
are
simple
nitrogen
results
for
dye
in
conjugation
dyes.
derived
parameters
when,
the
dihydroperimidine
when used
(131h),
ring
n-system,
in
example,
failed
to
For
nitrogen
the
PPP-MO
available
calculations.
dihydroperimidine
each
for
arylamines
these
the
of
previously
simple
in
rest
than,
Therefore,
for
and perimidine
the
with
donated
more readily
aminoazo
satisfactory
in
give
example
the
was given
H
N
H
N&N02
(131h)
VSIP value
being
for
those
for
allow
perimidine
lowering
of
strength
543nm,
values
alkylated,
nitrogen
ring
enhanced
the
of
values
in
a shortfall
of
fact,
non-hydrogen
only
found
(131h)
and the
the
5nm from
to
bonded
give
values
group),
the
is
again
electron
in
the
therefore
were
increased
results
(these
observed
evaluated
by dihydroperimidine
exhibited
14.8eV
atoms)
values
If
8.0eV
some 58nm from
of
affinity
showing
nitrogen
a deviation
were,
to
of
dimethylamino
the
atom of
atoms.
VSIP value
affinity
+M effect
nitrogen
new these
the
best
overall
donating
A..
value.
4.0eV
to
affinity
a calculated
observed
then
considered,
electron
the
and
value
nitrogen
releasing
in
strength
dyes
for
results
non-
ring
perimidine/dihydroperimidine
(134b)
due to
the
and
+I
(135b)
has
contribution
of
The two
atoms.
The N-ethyl
electron
nitrogen
and electron
the
the
and an electron
was 489nm,
New VSIP
value.
(both
the
A...
calculated
to
18.0eV
of
additional
from
the
alkyl
78
substituent.
13.8eV
Accordingly,
and the
the
electron
standard
n-equivalent
electron
affinity
to
affinity
ring
3.0eV.
nitrogen
0.5eV
=
was further
VSIP value
were
values
the
two dyes
12.0eV
=
VSIP
of
for
employed
these
For
to
reduced
remaining
and
ring
nitrogens.
For
at
reasons
shorter
dyes.
and electron
to
than
wavelengths
dihydroperimidine
were
discussed,
previously
affinity
from
raised
for
allow
to
effect
-I
in
for
values
the
(130i)
the
absorbed
PPP-MO calculations
dihydroperimidine
15.8eV
and from
the
a-carbonyl
of
(131i)
and
2,2-disubstituted
other
Therefore,
14.8eV
the
the
dyes
4.0eV
the
nitrogen
to
5.2eV
atoms
respectively
These
group.
VSIP
new values
A
then
gave
calculated
The hydrogen
dyes
coupled
bonded
again
When calculating
absorbance
hydrogen
bonding
could
mentioned
VSIP
electron
from
Apart
described
agreement
its
that
values
for
para-coupled
Having
experimental
obtained
Amax
for
dyes
these
the
but
the
ortho
values.
presence
by retaining
for
nitrogen,
to
the
of
previously
increasing
of
for
the
the
(132)
differs
there
and
are
is
from
markedly
good
were
in
exceptional
the
calculated
17,
higher
than
those
between
the
in
in
presented
Table
listed
those
were
and
was generally
Dye (133)
(133)
dyes
the
dyes
Emax values
atom
Calculated
representative
that
donor
nitrogen
and experiment.
value
max
with
the
applicability.
can be seen
theory
agreement
strengths
oscillator
other
general
A
for
and bond parameters
for
It
observed
In
value.
19.
between
14.8eV
atom
other
Amax
18 and
Tables
affinity
modifications
elsewhere
experimental
new VSIP and electron
in
6.0eV.
these
all
parameters,
atoms
values
experiment.
with
nitrogen
be compensated
of
to
affinity
good agreement
dihydroperimidine
required
value
in
values
max
the
for
the
dyes.
correlation
a reasonable
values
of
the
azo dyes,
it
was then
calculated
of
interest
and
to
79
Table
18:
A
PPP-MO calculated
4-nitrophenylazo
A
Dye
for
values
ý. x
dihydroperimidines
A/
nm
(Toluene)
. sx/nm
(Calc)
(130h)'*
557
562
(130i)
532
523
(134a)
556
550
(134b)
569
558
dihydroperimidine
any
-
19:
Table
A
548
(131i)
520
523
(132)
480
505
(133)
505
395
(135a)
577
578
(135b)
592
580
any dihydroperimidine
for
changes
better
the
(134b)
of
respectively.
(135b)
are
It
electrical
should
be noted
charge,
that
i. e.
-110
1.34
+1
1.23
-12
1.26
in
a positive
density
and n-electron
the
dyes,
in
for
Figures
dyes
to
order
their
between
values
Figs.
here
may be substituted
relationships
colour
obtain
a
and
(131h),
(130h),
and 8
5,6,7,
of
as representative
the
ortho
and
refer
to
dyes.
and perimidine
dihydroperimidine
+25
1.84
of
can be regarded
These
+3
charge
summarised
Oscillator
stength
(f)
(Calc)
0.82
densities
in
para
1.09
(131a)-(131g)
the
here
+5
dye
The relevant'
structure.
and
/nm
AA.,,.
(Tol - Calc)
transitions
visible
understanding
molecular
Para
state
ground
-11
1.63
representative
and perimidines
543
the
-6
1.70
for
values
max
dihydroperimidines
(131h)'
examine
-9
0.81
may be substituted
.,ax/nm
(Calc)
"-
0.52
(130a)-(130g)
A,,,,,. /nm
(Toluene)
Dye
+5
A
PPP-MO calculated
4-nitrophenylazo
ortho
oscillator
stength
(f)
(Calc)
m. x/nm
Calc)
-
(Tol
dye
representative
and perimidines
5(a)
sign
8(a),
-
the
means positive
charges
charge,
a
80
negative
sign
in
means a gain
a decrease
5:
Fig.
in
(negative
density
electron
density
electron
at
charge)
a particular
charge densities
first
absorption
(a)
Ground state
for the
changes
8(b)
-
5(b)
In Figs.
charge.
a negative
a positive
sign
and a negative
sign
atom.
density
and (b) n-electron
band of (130h)
". 388
0
I
+.o1
1-. 043
Hý
022
+.
+. 017
412012
-.
I
079
-.
J+. 023
I+. 042
.. 125
0-. 380
N-. 076
182
-.
196
075
.
I+.094
.oH
N+. 65
N616N
J-.
034
1 14I-.
712
N+
-. Ob3
+. 051
(a)
0
1
+. 015
+.038
,N
005
011
+.
.
+. 035
NN3
012
L
.
02
11
-.
öH
N+.025
11
057
+.
N+. 216
J+.
041
+.
144
; 02
+. 001
11B
-.
+.00,b
017
+.
025
123
-.
Amax
(b)
A
max
be
seen
can
It
Para
dyes
migration
nitrogen
the
of
from
n-electron
electron
atoms
O+_051
principally
(5a)
Figs.
system
density
to
and
in
the
from both
the
(6a)
donor
acceptor
557nm
=
(toluene)
562nm
=
for
that
ground
(caic)
state
both
shows
the
the
ortho
and
typical
dihydroperimidine
azo-
and nitro-groups.
In
81
the
case
(130h),
of
to
conjugated
Fig
6:
the
azo group
(a) Ground state
for the
changes
shows
nitrogen
directly
not
donation
a greater
charge densities
first
absorption
of
electron
and (b) n-electron
band of (131h)
density
021
02
+.
-.
H
N-
+"545
118
-.
^084
N+-103
6
the
surprisingly,
rather
00x.,
011
385
\
H
/
N
204
062
+.
-.
.
-. 07
+-076
235
N+
\0 -712
5
-'
014
0
08
+.
-.
(a)
H
153
+. 01
-.
N05
. Z
001
.
017
.
016
003+.
-.
+'125
017
.
0,0 +. 039
-N
031/O+.
+.
N+. 10
5
H
11
-.
121
+. 054
4
044
-.
0+. 120
... 034
0.0
A
(caic)
`b)
543nm
=
max
Amax (toluene)
density
the
than
is
reverse
density
electron
dyes.
Clearly
occurring
state
in
typical
electron
migration
the
the
at
the
para
B-azo
ground
Consideration
polarised.
Again
for
true
atom
nitrogen
of
the
n-electron
donor-acceptor
density
electron
change
density
in
nitrogen
of
Figs
system
both
the
are
from
the
para
dye
nitrogen
a build
state
ground
accompanying
the
also
are
shows the
characteristics
for
is
molecules
5(b)-8(b)
The
conjugated.
There
(131h).
dye
states
of
directly
is
that
548nm
=
light
both
in
strongly
changes
absorption.
The excited
shown.
(131h)
up of
shows a small
atom para
to
the
azo
82
Fig
7:
(a)
Ground state
for the
changes
charge densities
first
absorption
and (b) n-electron
band of (134b)
density
-. 38
0
+.o1
Et
N-.
N+1.126
N-. 113
1i
14
-.
0000,
7o
.
+.014
X019
018
.
06
-. 38
+. 0 18
0.0
11
0.0
7
N
023
-.
+. 068
1
N-.1o-5
-. 10
J+. 021
+. 04
064
-.
0
-. 076.
(a)
+. 015
0.0
Et
N
N -. 002 N-. 086
N
ö22"ý0+.
04
+. 015
019 0.0
1+.059
0.0
T+. 013
026
-.
+. 038
+. O29
146
15
.
A
+, 024
+03
.0
08 4
.
(caic)
= 560nm
(toluene)
= 558nm
max
-. 14
max
(b)
largely
group
is
typical
of
positions
of
other
the
and para
to
electron
density
donating
groups
in
The perimidine
that
illustrate
of
the
to
the
atoms)
with
dyes
(134b)
fact
that
dihydroperimidine
the
positions
and
their
dyes
indicates
would
the
group.
This
2,4,6,
and 8
positions
ortho
decrease
in
that
electron
contribute
Electron
shift.
Para
(i. e.
show a strong
This
bathochromic
nitro
(130h)
system
state.
these
in
Also,
ring
exited
attached
pattern
show a similar
dyes3.
nitrogen
the
atom and the
nitrogen
dihydroperimidine
donor
the
a-azo
aminoazo
additional
significant
to
the
onto
a
density
changes
dye.
(135b)
are
behaviour
n-electron
(130h)
included
and
(131h).
in
is
Figs.
similar
7 and 8
to
83
Fig
8:
(a) Ground state
for the
changes
charge densities
first
absorption
and (b) n-electron
band of (135b)
densit
096
023
+.
-.
129
N
-.
NII0068
+1.093
_
/
Et
N09ß
OSß
+. 003
+. 014
0-. 38
%
N
20
+.
17
061
+.
-.
-. 106
06
-. N+.711
-. 006
-"3ß
\O
+. 011
(a)
011
099
+.
-.
0.0 N
002
_.
+. 00 3
-. 09_ N+073
/
Et
12
-.
+. 019
+. 137
X01
-. 153
+_18
\\
+. 068
146
-.
±033
N
0.0
0+. 042
+.023
N
0314
,
\
p+.oß.
2
014
+.
±006
(b)
A.
(caic)
= 592nm
(toluene)
580nm
=
A...
2.1.2.3
Halochromism
The 4-aminoazo
shown
in
colour
dyes
the
Azo Dyes
undergo
the
various
protonation
equilibria
Scheme 21 "'''24.
ion
The azonium
differs
of
in
(145)
colour
from
is
called
change
is
the
formed
generally
neutral
halochromism.
dye
(143).
predominantly,
This
acid
and
induced
84
N=N
NR2
x\/
10-
N=N
H
(143)
X
N-
NR2
`
(144)
Jf
N
NR2
X
.4--00.
N=
N
NR2
HH
(145b)
(145a)
Scheme 21
The azonium
ion
dye
unprotonated
halochromism.
and the
the
of
involves
charge
on going
from
electron
withdrawing
powerful
electron
strength
dye
is
to
neutral
said
shift
is
to
acid
releasing
in
groups
donating
electron
high
sufficiently
of
zero
equal
of
or
shift
increasing
with
introduction
of
more
ring.
the
and/or
even
which
bathochromic
amino-substituted
groups
then
nearly
neither
the
the
with
the
positive
the
decreases
X, or
the
exhibit
(145b),
4'
solution
of
than
due to
The magnitude
strength
the
then
(145a)
structures
separation.
of
is
acceptors
more bathochromic
usually
The bathochromic
contributions
the
is
If
electron
halochromism
negative
may be observed.
The halochromism
azo dyes
were
fractionally
Shifts
of
the
the
sodium
restored,
pure
and dried
are
spectra,
bicarbonate
completely
in
absorption
acid
to
dihydroperimidine
representative
determined
distilled
hydrochloric
recording
of
maxima
summarised
solutions
verify
thus
over
(the
solution
acetone
a zeolite
Table
20.
were
carefully
that
the
original
showing
that
the
solvent
molecular
In
all
solutions
cases
neutralised
spectra
observed
was
sieve).
the
of
on acidification
in
and perimidine
could
spectral
with
after
with
be
changes
85
20:
Table
Halochromism
of
dihydroperimidine
A
Dye
4-nitrophenylazo
dyes
representative
and perimidine
/nm
(acetone)
.,,,.
&A m.x/nm -
Neutral
+HC1
(acidic-neutral)
(130h)'ß`
570
603
+33
(131h)
555
581
+26
(132)
515
550
+35
(133)
391
378
-14
(134b)
571
477
-94
(135b)
594
494
-100
observations
were
- similar
dihydroperimidine
dyes
are
due
not
irreversible
to
in
The results
In
20 show that
Table
dye
contrast
form
not
3-nitrogen
atom
the
dyes,
ortho
and Para
as dye
(132),
solvatochromism
on
as well
is
the
negative
exhibits
almost
due to
certainly
instead
but
cation
an azonium
in
processes.
exhibit
on acidification.
(133)
This
2,2-disubstituted
other
decomposition
solvatochromism
acidification.
does
for
dihydroperimidine
4-nitrophenylazo
positive
found
dihydroperimidine
the
fact
this
dye
on the
protonates
(146).
giving
ring,
that
This
0H
N
EtO
/
N
H
\N
N022
H
(146)
would
group
donor
The
give
is
a hypsochromic
an indication
nitrogen
isomeric
atoms
shift.
of
to
perimidine
the
the
to
The failure
very
weak donation
azo group
based
dyes
in
the
(134b)
protonate
of
neutral
and
on the
electrons
from
azo
the
dye.
(135b)
exhibit
marked
86
halochromism.
negative
larger
than
As with
3-nitrogen
a possible
atom
of this
be anticipated
might
(133),
The size
the
of
for
formation
is
explanation
perimidine
(ca.
shift
ring
100nm) is much
of an azonium
that
on the
protonation
as shown in
occurs,
cation.
Scheme 22.
Et
NN
NO2
Me
N
(147a)
Et
NN
NOS
`/
Me
H\/
(147b)
Scheme 22
Protonation
perimidine
the
ground
indicates
which
has
residue
atom
of
ortho-analogue
2.1.2.4
Stability
(130)
the
the
-
in
Properties
(135)
are
of
(135b).
density
data
would
is
dye
for
the
absorb
This
atom of
than
the
at
(135b),
much
by
[Fig.
perimidine
B-nitrogen
atom of
at
The same situation
ring.
the
supported
preferentially
occur
should
perimidine
Fig.
dye
density
electron
the
(147)
3-nitrogen
of
ability
4-nitrophenylazo
the
species
neutral
charge
state
properties
The stability
dyes
protonated
the
reduce
to
electrons
Hence protonation
azo-linkage.
3-nitrogen
donate
that
a greater
significantly
would
than
wavelengths
calculated
the
to
therefore
shorter
8(a)]
site
residue
residue,
the
this
at
the
the
exists
for
7a.
Of Dyes
of
the
practical
(135)
highly
-
(140)
bathochromic
relevance
if
they
simple
are
to
monoazo
be used
87
technically.
The dyes were considered
in
application
in
data
optical
inks.
opto-electronic
storage
Accordingly
for
such
as laser
systems,
media
both
largely
as dyes
or
the
thermal
was to
cast
for
their
in
use
potential
light
absorbers
machine-readable
and photochemical
properties
were
assessed.
The method
the
containing
be subjected
dye
the
dye
to
not
in
a fully
heat
or
purposes,
and this
was readily
in
soluble
and the
which
as textile
(148)
cellulose
then
could
degradation
of
For
spectroscopy.
dye was required
azo dye
acetate
Such films
state.
absorption
as far
thiazole
cellulose
treatment
by visible
stability
The blue
concerned.
of
dissolved
a standard
exceptional
films
photochemical
directly
assessed
comparison
but
adopted
had reasonable
applications
was elected
were
as standard,
acetate.
N
S
p2N
(148)
For
photostability
and mounted
film
dye
made up with
Microscal
before
(148)
were
together
of
into
with
small
the
72 hours
for
densities
and the
irradiation
was cut
irradiated
The optical
Fadometer.
and after
The films,
frame.
on a slide
film
each
evaluation,
the
pieces
standard
a
using
films
measured
were
degradation
percentage
determined.
In
dyed
to
order
films
sealed
in
dye
dye
could
assess
sandwiched
were
printing
the
of
press
films
subliming
at
the
for
The Melinex
acetate
film
and to
pieces
the
From the
the
permit
plates
the
of
optical
loss
percentage
was employed
of
film,
clear
between
1 hour.
heating,
dyes,
(Melinex)
and heated
and after
film
the
a polyester
envelope,
190°C
of
stability
between
before
be calculated.
from
thermal
foil
an aluminium
a transfer
density
the
to
detection
trap
of
any
this
of
88
dye.
In
this
from
separated
the
of
way dye degradation
Melinex
sublimation
loss
only
a qualitative
the
conditions
the
represents
true
for
The results
Table
21 and those
Table
21:
calculated
for
the
assessment
degree
the
of
percentage
loss
dyes
coupled
in
22.
Table
dye.
the
of
of dye in each
are
Photo
Thermal stability
(% loss)
stability
loss)
5
(130f)
20
V`
(130g)
15
16(`'
(130h)
17
3c10'1
(130i)
32
2
(134b)
17
7`''
(148)
dye
some
-
showed
a 5% loss
thermal
treatment.
sublimation
strictly
sublimation
relative
derivatives
from
(148).
Tables
but
The thermal
as,
quantitative,
was evident,
stability.
appeared
It
to
u. v.
in
but
is
all
they
sublime
dyes
new
the
fastness
heat
superior
quoted
values
stability
degrees
varying
cases,
do give
interesting
and an 8% dye
radiation
21 and 22 that
lightfastness
inferior
standard
to
on exposure
can be seen
showed
dye
The standard
8
It
in
summarised
Thermal
and photochemical
stabilities
of representative
4-nitrophenylazo
dihydroperimidine
ortho
coupled
and
dyes
perimidine
Standard
(a)
of
showed no transfer
ortho
dyes
opacification
dyes which
degradation
para
be
could
due to
However,
For those
representative
film
acetate
visual
thermal
Dye
the
the
by sublimation.
be made.
could
these
under
case
dye
in
to
more readily
a general
note
that
than
guide
the
their
loss
on
generally
relative
are
of
not
dye
as to
ortho
Para
to
the
89
Table
22:
Thermal
and photochemical
4-nitrophenylazo
para coupled
dyes
perimidine
Dye
Photo stability
(% loss)
(148)
Standard
(a)
(b)
Thermal
stability
(% loss)
8
5
(131f)
42
3c=)
(131g)
45
2(')
(131h)
43
21`'
(131i)
41
(132)
58
14(='
(133)
45
2(`'
(135b)
28
3
Total
Decomposition()
dye
some
sublimation
by
dye
followed
the
decomposition
the
or
products
of
- sublimation
brown
due
to
decomposition
on
staining
apparent
was
subsequent
film
the Melinex
hydrogen
bonding
polarity
and higher
The dyes
the
again,
isomers.
all
dyes
Those
which
[but
(132),
assessed.
accelerates
showing
(131i)
dye
and
It
lower
to
intramolecular
dyes
of
reduced
stability
in
bonding
groups,
carbonyl
contained
ester
of
(133)],
the
the
ortho
ortho
dyes
destroyed
the
(132)
showed
would
seem that
of
worst
the
these
generally
under
other
the
of
dyes.
thermal
of
photostability
presence
dyes.
the
the
(131i)
(130i),
namely
exhibited
than
stabilities
was totally
degradation
than
with,
stability.
greater
the
however
properties
hydrogen
intramolecular
and thermal
photochemical
employed,
not
leads
derivatives
lightfastness
poor
analogues
the
ortho
the
that
volatility.
Presumably
contributes
example
within
exhibited
para
to
the
fact
by the
can be explained
This
analogues.
and
stabilities
of representative
dihydroperimidine
and
all
carbonyl
poorer
For
conditions
the
dyes
group
90
In conclusion,
dyes
are
the
in
it
can be said
for
satisfactory
stability
plastics,
temperatures.
which
would
2.1.3
Highly
etc.
is
generally
limit
severely
Bathochromic
such
their
to
poor
practical
Monoazo
materials
moderate
the
closely
with
be used
could
processing
dihydroperimidine
photochemical
and
stability
in
applications
on Other
Dyes Based
of the
stabilities
and compare
drawback
main
their
Thus
employ
which
the
However,
systems
perimidine
azo dyes.
coatings
thermal
applications,
most
textile
of
the
that
many areas.
Coupling
Novel
Components
In
addition
groups
dihydroperimidine
apparently
other
components
bis
to
azo dyes
for
very
are
and perimidine
known.
Two such
d)indole
1-decyl-2(1H)-methylene-benz[c,
coupling
examined
systems
(Michler's
1aminophenyl}ethene
44-dimethy
in
nucleophiles
powerful
donor
electron
(149)
ethylene)
the
were
and
(150).
Dec
CH2
N
Met
Me2N
I
I
CH2
(150)
(149)
Non-azo
the
literature
dyes
from
these
and demonstrate
the
derived
two
systems
extremely
have
been reported
bathochromic
+
1e2
Me2N
CH --
CH
Met
Me2N
(151)
nature
in
of
91
these
(151),
the
donating
electron
derived
from
Michler's
electron
methylene
absorbs
the
ethylene,
a powerful
two
of
the
and in
dye
cyanine
Evidently,
for
4-dimethylaminophenyl
to
conjugated
species,
the
example
810 and 663nm126.
at
effect
species
nucleophilic
ethene
effect
residue
in
results
a reactive
active
benzindole
residue
group.
The highly
(150)
(149)
releasing
For
residues"'.
bathochromic
can be seen
contribution
by considering
dye
The corresponding
colour127.
the
of
(152),
(153)
system
is
which
is
only
blue-green
in
red
in
colour
even
/CH3
ýN
CH3
\CH
CH
-
N
CH2CH2CN
(152)
CH3
C H3
CH3
5000,
CH-
ý/
CH
N
CH2CH2CN
CH3
(153)
though
it
same conjugation
path
1.8-linkage
of
contributes
special
cannot
are
2.1.3.1
for
solid
dry
(154)
ether,
could
but
the
in
light
by conventional
the
the
residue
bathochromic
ethylene
via
between
naphthalene
of
in
-NMe group
length
readily
Synthesis
Michler's
ketone
the
be explained
accounted
pure)
a donor
contains
by the
a 5-membered
nitrogen
absorption
the
species
These
properties.
theory
resonance
Clearly
atoms.
benzindole
the
and has the
ring
but
arguments
PPP-MO method.
Dyes and Intermediates
(149)
route
was obtained
shown
be made to
reaction
in
as a pale
Scheme 23128.
react
was slow,
with
methyl
and it
green
(white
when
Thus Michler's
magnesium
was necessary
iodide
to
in
exclude
92
Me2N
Me2N
NMe2
1
NMe2
1
MeMgI / 22h / Dark
Dry
0
I
CH3
I
Et20
OMgI
(154)
H2O
NH. C1/CH3000H
Me2N
NMe2
C H2
(149)
Scheme 23
light
in
during
low
the
(ca.
yields
The synthesis
posed
Scheme
decylbromide
have
effected
sodium
under
transported
phase
in
occurred
of
the
magnesium
hydrochloric
acid
naked
(156)
organic
iodide
gave
that
Thus
transfer
the
(144)
gave
hydroxide
in
dry
crystals
product
shown in
was actually
For
(155)
N-alkylation,
resultant
into
giving
(157).
ether
followed
Thus
the
the
was
aqueous
phase,
where
bromide
by n-decyl
reaction
by treatment
1-decyl-2(1H)-methyl-
dyes
18-crown-6
organic
Grignard
n-
n-decyl
concentrated
with
N-Alkylation
of
is
The N-alkylation
18-crown-6.
occurred.
phase,
the
solubilities.
anion
(150)
(150)
1-naphthylisocyanate
that
conditions
using
to
(156).
was felt
solvent
solution
the
deprotonation
methyl
organic
hydroxide
acid
d]indole
route
d]indol-2(1H)-one
as it
was used,
good
(158).
salt
benz[c,
chosen
be noted
should
iodide
to
was converted
would
and the
It
as the
acetic
1-decyl-2(1H)-methylene-benz[c,
problems,
24129-133.
isolated
dilute
28%).
of
several
Work up with
reaction.
with
then
with
dilute
93
benz[c,
d]indolium
iodide
(158).
H
NCO
0
N
i.
A1C13 / ODCB / Reflux
ii.
NaCl
/
/
100°C
/
1h
15min
(155)
(156)
bromide
n-decyl
45% NaOH / 18-crown-6
ODCB
CIOH21\
0
C10H21 \+
N
H3
N
i.
/
MeMgI
ii.
Dry
ether
l
H30'
,/
(157)
(158)
Scheme 24
The structure
clearly
showed
the
(158)
atom.
an intense
showed
by mass spectrometry
was proved
ion
a molecular
iodine
the
minus
also
of
is
It
peak
308,
m/e at
also
m/e=168,
at
to
equivalent
interest
of
that
presumably
which
the
the
salt
mass spectrum
to
corresponding
(159).
species
H
CH3
N
1
(159)
The severe
and attempts
essential,
sulphate
amides
alkylating
under
gave
typical
no reaction.
conditions
to
ethylate
conditions
It
would
to
used
the
used
prepare
benzindole
for
therefore
the
(158)
(156)
using
N-alkylation
seem that
were
of
diethyl
primary
deprotonation
94
the
of
NH in
amide
Diazo
coupling
(156)
to
achieve.
dissolved
in
ethanol
diazotised
For
with
612nm was observed.
but
same blue
This
9:
Even a sodium
product,
blue
product
whose
UV-visible
spectrum
dichloromethane
was thought
that
showed
acid
is
spectrum
of
surprisingly
(149)
ethylene
to
in
absorbed
be the
would
Michler's
protonated
proved
that
buffer
shown
amides.
was coupled
to
alone
acetate
simple
Michler's
buffer
this
for
(158)
acetate
an intense
tests
compound.
result.
Fig.
simple
and
when the
example,
Initially
than
(149)
a sodium
4-nitroaniline
product
more difficult
intermediates
of
difficult
is
at
desired
the
generate
gave
the
Fig.
9,
same
is
the
in
ethylene
ro
H
lýf
1.2
A
,,
v.
0.6
62
00
/ run
wavelength
A-
absorbance
Michler's
methyl-substituted
protonation
of
the
ethene
Blue
Hydrol
residue.
cation
Attempts
Me2N
\
It
14
CH3
(160)
to
NMe2
(160),
formed
couple
the
by
benzindole
95
derivative
(158)
unsuccessful
It
best
and gave complex
found
was eventually
be effected
4-nitroaniline
ethanolic
4-nitrobenzenediazonium
with
the
with
the
of
desired
diazonium
coupling
reactions
tetrafluoroborate
by dissolving
(161)
solution
the
were also
of products.
mixtures
that
chloride
it
requisite
in
ethanol,
active
salt
could
of
it
and adding
methylene
compound
to
an
(Scheme
25).
N2'BF4-
EtOH / Stir
at
25°C /
NO2
XNN`
X
1h / Filter
NO2
(161)
Dec
CH3
N
Me2N
g=1
I
NMe2
/
/
\
or
CH2
(150)
(149)
Scheme 25
The Michler's
recrystallised
dye
ethylene
from
Me
ethanol.
(162)
could
be filtered
was confirmed
The structure
N
/,
CH-
N =N
ýI \1
Me2N
(162)
off
\/
NO2
and
by mass
96
Spectrometry.
The benzindole
t. l. c.
scale
and the
dye (163)
structure
also
by preparative
was purified
confirmed
by mass spectrometry.
4-Dec
N
CH -N
--
bl-
NO2
(163)
Unfortunately
dyes
using
it
was not
2.1.3.2
salts
Light
(163)
were
comparison
with
were
dichloromethane
in
Table
23:
in
salts,
molecular
orbital
pure
these
anhydrous
the
PPP-MO calculated
values
(162)
For
in
values
results
are
for
dyes
the
toluene
for
calculated
were
The spectroscopic
dyes
of
and toluene.
coefficients
summarised
are
24.
Table
data
Spectroscopic
dyes
4-nitrophenylazo
for
Emaxllmol-'
max/nm
(162)
Q
cm-'
and
Amax/
(163)
rm
(CH2C12-Tol)
(CH2C12)
(Toluene)
(CH2C12)
41,500
681
554
(162)
54,500
583
The solvatochromic
as this
interesting
in
13,500
575
584
(163)
is,
relevant
samples
calculations
A
That
the
of
be isolated.
analytically
absorption
Dye
any analogues
since
dichioromethane
solutions.
in
summarised
of
measured
23 and the
Table
not
synthesise
Properties
spectra
Molar
used.
could
Absorption
The absorption
and
diazonium
more powerful
tetrafluoroborate
to
possible
exhibited
effects
dye
dichloromethane
shows
characteristics
the
dye
exists
by
(162)
of
-11
are
particularly
allopolar
im two distinct
isomerism'.
isomeric
97
forms,
(162a)
namely
and
dimethylaminophenyl
(162b).
is
rings
nitrophenylazo
---------------
twisted
(162a)
one of
out
the
of
"meropolar"
This
residue.
In
the
N, N-
plane
isomer
is
the
of
for
responsible
-1
11
1met
1I
1
out
1\
r-
1
of
plane
-----------------------
NMe2
Me2N
1t
1
;
CH
1I
t
-----------
N'
II
CH
t
a
'N'
11
coplanar
N
I/tf
N
II
t_
-------------------
out of
plane
00
coplanar
(162a)
(162b)
the
peak
583nm.
at
form,
contains
plane
perpendicular
is
residue
for
the
more
the
peak
only,
to
the
to
681nm.
at
form
solvent
toluene
to
the
charged
is
It
is
the
dye
the
form
positive
single
only.
residue
and is
is
in
a
chromogen
thus
not
absorption
Considering
solvatochromism.
responsible
the
more polar
form
holopolar
Thus
Blue
the
"holopolar"
The cyanine-type
Therefore
stabilised'34.
meropolar
exhibits
known that
the
the
cyanine-type
residues.
Hydrol
Michler's
termed
4-nitrophenylazo
charged
positively
concentration.
due
(162b),
N, N-dimethylaminophenyl
holopolar
low
554nm is
negatively
analogous
peak
non-polar
a very
the
both
containing
isomer,
The second
in
the
stabilised
peak
the
In
the
solvent
relatively
and has
observed
at
meropolar
acetone
the
98
high
polarity
holopolar
form
(162b),
The relatively
though
even
absorbs
increase
the
high
planar
in
dye
two peaks
extinction
this
not
occurring
the
of
568 and 677nm.
at
for
present
the benzindole
but,
dye
is
in
(162)
the
within
low
relatively
for
cm-1),
and this
is
benzindole
electron
donor
residue.
The PPP-MO calculations
and electron
affinity
dimethylamino
group
using
Evidently
such
show that,
isomers,
the
the
unusual
be handled
cannot
is
geometry
24:
the
positive
about
feature
for
the
of
N, N-
a standard
calculated
observed
max
by some 45nm.
value
this
of
PPP method
a simple
planar
assumed.
A
A
m.,
values
A
max/nm
for
dyes
(162)
AAm.. /nm
(Tol-Calc)
ma,c/nm
(Toluene)
(Calc)
(163)
and
Oscillator
(f)(Calc)
strength
(162)
509
554
+45
1.23
(163)
573
575
+2
1.01
For
dye
affinity
it
(163)
for
values
was necessary
the
7.75eV
nitrogen
enhanced
values.
satisfactory
for
atom
the
gave
electron
VSIP and electron
a satisfactory
releasing
to
find
benzindole
ring
Amax
calculate
dye
particular
if
the
The VSIP
problems.
properties
by the
satisfactorily
(usually
those
of
spectroscopic
PPP-MO calculated
Dye
and
dye
coefficient
an intrinsic
However
short
exhibits
extinction
presented
were
atom.
fell
values
(162)
also
the
an azo dye
used
nitrogen
(162),
presumably
for
values
dye (163)
to
contrast
30,0001mol
Table
concentration
coefficients
is
geometry
(162),
solvatochromism
value
the
strongly.
As with
of
in
results
capacity
new VSIP and electron.
in
nitrogen
Semi-empirical
affinity
of
the
to
of
values
for
respectively
The values
result.
order
nitrogen
the
the
reflect
atom
in
17.75eV
a
99
5-membered
ring
calculated
oscillator
with
the
low c...
The ground
for
Fig.
compared
the
for
strength
(163)
is
nitrogen
The
atom.
low,
relatively
consistent
value.
state
densities
charge
transition
visible
10:
N-alkyl
a normal
with
of dye (163)
(a)
Ground state
for the
changes
changes
are shown in Fig.
densities
transition
charge
visible
density
and n-electron
and (b)
of dye
10.
density
n-electron
(163)
0.0 -. 012
066
-.
0.4(
049
055
-.
0.0
+. 03
SCH-NN
035
-.
0-. 37
454
+.066
Nf. 71
-. 20
,. 11
6
05
-.
0-. 37
045
+.
00
+. 012
0.0
0.0
+.0 16
(a)
0.0 0.0
+. 012(
.+. 2 7
o:0
N-.ta
0.0
+. 07
0.0
15
-.
+10
3
0
+.
NC
N
H_. _._N---
0.0
Amax
Amax
n-electrons
the
nitro
at
group.
On excitation,
nitro
that
of
groups.
charge
is
evident
benzindole
the
Thus
the
the
electron
The fact
separation
that
the
polarised
system
from
the
= 573nm
(toluene)
575nm
=
a deficiency
shows typical
molecule
density
is
(calc)
and an excess
nitrogen
n-electron
in
there
that
a highly
and has
characteristics,
migration
it
0+.006
0.0
015
-.
(b)
10(a)
o» N+.006
047
.
+.09
- .21
07
+.
+. 07
From Fig.
Q +, 00B
polarises
the benzindole
overall
ground
ground
state
migration
is
of
of
electrons
on
donor-acceptor
state.
further
ring
is
maximal,
with
a small
to the azo and
small
i. e.
suggests
the
ground
100
state
shows a high
that
forms
(163a)
In
state].
degree
such
of bond uniformity
and (163b)
the
cases
[in
make an equal
excited
state
this
effect,
to the ground
contribution
will
implies
show only
a small
degree
/Dec
N
0
CH-N
cNN
0
(163a)
+/
N
Doc
>
<:
CH__ NN
ý0
(163b)
of
charge
Other
migration.
chromophore
consequences
maximum bathochromicity
shows
this
of
are
and is
also
that
the
weakly
solvatochromic.
discussed,
As previously
occurs
ion
almost
exclusively
tautomer,
dye.
examined,
Table
25:
at
and the
The effects
of
and the
shifts
the
in
shift
acid
Absorption
and acidic
protonation
on the
in
spectra
solutions
of
B-azo
Amax
of
maxima
azo dyes
Amax/nm (acetone)
Dye
Neutral
(162)
+HC1
(162)
the
and
(163)
shown in
are
and
(a)
- point
of
inflexion
azonium
Table
neutral
- neutral)
568
581
+13
677
645'
-32
558
559
+1
of
the
were
/nm
AA m.
(acidic
in
(163)
(162)
(163)
dyes
halochromism
the
called
spectra
form
to
nitrogen
is
absorption
of
4-aminophenylazo
25.
101
In
all
the
cases
a weak
protonated
bicarbonate
sodium
be completely
could
In
the
true
only
solutions
case
dye
azo peak
this
halochromic
shift.
halochromism
(162),
is
that
peak
(165)
protonation
exhibits
the
meropolar
this
be produced
is
of
longer
to
shifts
species
azonium
that
ensure
which
of
However,
could
normal
to
solution
neutralised
the
with
original
spectra
restored.
of
protonation
carefully
were
in
the
is
amino
the
On
a positive
since
a positive
(164)
In
ways.
the
be bathochromic.
would
which
568nm.
at
ambiguous
two different
formed,
one of
form
wavelength,
result
isomerism,
allopolar
This
occurs.
groups
In
in
effect
Me 2N
CH -
NON
N02
\/
H
Me2
(164)
HMe2
<D
<::
Me2N
NO2
-
N
N=
CH 0
(165)
produces
an
a -I
'unstarred'
bathochromic
aryl
position
shift
at
substituent
is
within
also
the
predicted.
position
concepts
# as shown.
of
On the
PMO theory,
presently
Since
this
then
available
a
is
102
it
evidence
Dye
(163)
between
not
is
the
intensely
is
is
and
nitrogen
atom
2.1.3.3
Stability
the
26:
Table
band
the
and photochemical
in
Section
stabilities
being
appeared
in
destroyed
decomposition
test.
stability
it
Thus
concerned,
Dye
of
(163)
can be concluded
the
in
poor
have
little
complex
thermal
practical
each
dye
dyes
of
and
(162)
and
Decomposition
69
stability
with
occurred
during
half
more than
of
case.
exhibited
that,
electron
2.1.2.4
Thermal stability
(% loss)
Total
(162)
also
dyes
5
light
lack
to
these
of
8
76
dye
B-azo
26.
Table
(163)
Both
azonium
the
of
properties
described
58
Total
type
in
(148)
dyes
of
more
(163)
and
stability
(162)
result
typical
Photo stability
(% loss)
Standard
observed
distinguishing
protonation
(162)
Dyes
of
procedures
Dye
the
that
evidence
summarised
Thermal
(163)
the
form absorbs
is
This
width.
(165).
and
occurring.
using
are
means of
the protonated
and photochemical
assessed
results
that
(164)
on protonation,
The only
Properties
The thermal
were
is
conclusive
is
between
because,
a narrower
cations,
decide
negligible.
two spectra
with
to
possible
interesting
Amax
in
shift
is
at
donor
and photochemical
potential.
least
poor
thermal
as far
residues
stability..
the
in
thermal
stability.
as azo dyes
(162)
and
are
(163)
Thus dyes
of
this
103
2.2
Methine
and Azomethine
from
Dyes Derived
N-Alkyl-3-cyano-6-
hydroxy-4-methyl-2-pyridones
The N-alkyl-3-cyano-6-hydroxy-4-methyl-2-pyridones
interest
commercial
as components
of
(166)
textile
dyes,
are
of
and more recently
CH3
N
I
HO
N0
R
(R = H, alkyl)
(166)
in
connection
example,
dyes
with
yellow
dyes
for
high
type
of
technology
(167)
have
R-0-C-0-C
been patented
Me
H
for
use
in
N
0
N-N
\/
For
applications.
lo l0
Rl
0
R, R'
= alkyl
(167)
thermal
transfer
The pyridone
condense
and will
(168)
types
and
in
the
D2T2 process
(166)
system
behaves
aldehydes
with
(169).
like
an active
and nitroso
The pyridone
photographyi'.
electronic
of
residue
compound
methylene
dyes
compounds
to
then
as a powerful
acts
give
CH3
CN
X-CH
X-N,
0N
pN0
R
(169)
(168)
acceptor,
electron
Bello
has
shown
as it
such
dyes
possesses
to
be red
a cyano
to
blue
and two
in
carbonyl
colour68.
groups.
of
104
A synthetic
the
is
variant
5-position
active
to
to
formylate
give
(170)
or
(171)
and
the
nitrosate
respectively.
CH3
CN
HO
ON
can
dyes
give
I
N0
NR
HO
(171)
be condensed
also
the
of
with
formula
general
other
(172)
active
methylene
(173).
and
X-CH-N
CN
7CN
\p
0N0
N
1
R
R
(172)
a longer
This
2.2.1
in
in
have
should
and such
dyes
types
with
(168)
and
a significant
investigated
were
for
Dyes and Intermediates
2.1.3.1.
Section
were
Formylation
Thus
ammonia
with
the
acetoacetate
the
(enamines)
crude
this
the
ethyl
to
(166;
(166;
the
amide
heated
was
R=H).
in
(175).
iodide
After
pyridones
addition
for
pyridones
could
as
with
effected
of
6 hours
N-alkyl
analogously.
be readily
(158)
was stirred
an autoclave
Other
Michler's
were
R=H) was prepared
(174)
cyanoacetate
form
work
d)indolium
The pyridone
mixture
pyridone
prepared
of
in
used
1-decyl-2(1H)-methyl-benz[c,
and
Scheme 26.
12 hours
groups
max,
methylenes
described
give
on
of
(149)
to
A
comparison
absorption.
ethylene
ethyl
in
conjugation
effect
The active
for
bridge
conjugated
Synthesis
shown
(173)
additional
bathochromic
infrared
would
C H3
X=CH-CH
(169).
to
compounds
Such dyes
CH3
possess
These
CN
(170)
species
at
CH3
OHC
i
pyridone
by the
105
NCCH2000C2H5 + NH3
(174)
Stir
12hours
Room temp.
/
CH3
CH3COCH2COOC2H5 / 6hours
X5ICH
/
NCCH2CONH2
/ Autoclave
120°C
HO
(175)
Np
tR
(166;
R=
H)
Scheme 26
Vilsmeier
reaction
pyridones
was carried
(POC13/DMF),
out
giving
with
nitrous
(176).
Nitrosation
to
acid
CH3
H
0=C
HO
CN
N0
N0
HO
R
(176)
compounds
(149)
resultant
dyes
were
column
products.
(177).
give
0=N
R
Condensation
the
CH3
CN
N
of
of
(177)
the
formylated
and
(158)
(178)
and
chromatographed
pyridones
in
was effected
(179)
were
over
the
with
refluxing
gel
to
give
Me2N
CH
CN
-CH
0/
N0
R
Me2N
(178)
methylene
ethanol.
The
from
recrystallised
silica
active
ethanol
analytically
or
pure
106
/Dec
N
CH3
CH-CH
CN
N0
0/
R
(179)
The azomethine
analogues
for
readily
and,
and the
active
temperature
in
analytically
example,
(178)
the
of
methylene
compound
could
ethanol.
After
samples
from
of
filtering
(180)
ethanol
(179)
and
reaction
pure
recrystallisation
of
pyridone
be effected
at
(181)
the
more
(177;
product,
be obtained
could
over
R=H)
room
precipitated
by chromatography
or
formed
nitroso
off
and
were
by
silica
gel.
Me2N
CH3
CH-N
N
N
p0
R
Me2N
(180)
Dec
N
CH3
CH-N
CN
ONO
1
R
(181)
2.2.2
Light
Absorption
The absorption
dichloromethane
determined
in
Properties
spectra
and toluene,
dichloromethane
of
dyes
of
(178)
and molar
only.
Dyes
-
(178)
(181)
absorption
The results
-
(181)
were
measured
coefficients
are
summarised
in
were
in
107
Table
27.
The structures
microanalysis
Table
27:
or
of
dyes
these
were
confirmed
(178a)
(181c)
by either
mass spectrometry.
Spectroscopic
data
for
dyes
-
CH3
CN
N0
1
R
Y
Dye
Ä
R
A
Emax
aac/nm
CH2C12
Tol.
(a
(x10-4)
)
A
(b
max
/nm
Me2N
(178a)
H- -CH-
-H
635
607
10.2
+28
-H
713
680
9.35
+33
-Et
631
603
8.50
+28
-Et
712
678
8.05
+34
635
607
4.52
+28
718
704
3.95
+14
-H
639
590
659
611
9.56
7.20
-20
-21
-H
698
646
701
649
6.50
5.54
-3
-3
-Et
655
606
658
609
9.05
7.05
-3
-3
694
645
694
646
7.10
6.25
Me2N
(180a)
-N-
(178b)
-CH-
(180b)
-N-
(178c)
4CH2)2NMe2
-CH-
(180c)
- -ECH2)2NMe2
Dec\
(179a)
(181a)
(179b)
(181b)
CH-
CH-
-N-
"CH-
N-
-Et
0
-1
108
Table
27:
continued
Dye
Y
X
A
R
Eanax (a)
max/nm
CH2C12
Dec`
(k
nax
/nm
&A:
(x10-`)
Tol.
CH-
(1790
CH- -f CH2)2NMe2
650
654
3.81(°)
-4
(181c)
-N- -{CH2)2NMe2
689
704
2.55(')
-15
(a)
= lmol-1cm-1
- unitsA
(b)
'&
-
(c)
=A
max
dyes
These
hypsochromic
show near-infrared
intense
were
Clearly
donor
than
those
derived
be readily
dyes
the
These
Michler's
the
are
that
summarised
in
dyes
(158)
state
ground
in
the
position
dyes
observation
are
can
derived
nitroso
has been
substantiated
by more
for
representative
and results
derived
and (181)
the
dye
from the benzindole
indicating
solvatochromism,
negative
exhibit
of
electron
28.
Table
(179)
bands.
atom.
nitrogen
observations
solutions
absorption
The latter
since
are
the
more bathochromic
an unstarred
PPP-MO calculations,
methylene
the
at
atom
the
(180c)
and
a more powerful
pyridones.
PMO theory,
more
(180b)
but
of
and the
electronegative
experimental
is
residue
nitroso
bridging
carbon
broadness
residue,
by the
explained
The pyridone
active
the
(180a),
dichloromethane,
the
ethylene
dyes
that
in
of
benzindole
from
quantitative
dyes
because
by a more
replaced
can be seen
absorption
green
the
max(toluene)
exhibited
only one peak. The second,
to a shoulder
peak was reduced
27 it
From Table
-A
max(CH2C12)
chromophore
is
than
more polarised
A
the
excited
values
polar
beyond
state.
Therefore,
700nm are
dichloromethane.
with
observed
This
dyes
(181a)
in
toluene
only
phenomenon
is
often
and
(181c)
and not
indicative
ma.
in
the
of
more
highly
109
Table
28:
Comparison
values
Dye
of PPP-MO calculated
dyes
representative
of
A
ma,c/nm
(Calc)
and representative
(178)
(181)
of type
-
AA
,max/nm
(Tol - Calc)
mix/nm
(Toluene)
Oscillator
(f)
max
stength
(Calc)
(178a)
589
607
+18
1.51
(180a)
664
680
+17
1.53
(179a)
643
659
1.67
611
(181a)
705
701
1.68
649
bathochromic
exhibit
positive
ground
The dyes
in
from
intensity.
less
the
so,
coefficients
and so give
N-Alkylation
of
intensity
the
longer
the
introduction
only
This
(see
and
whereas
the
twisting
(179c)
(181b)
of
in
the
and (181c)
not
are
However
of
'double
dye
in
accounted
these
the
peaks'
reduction
of
dye
(181a),
group
may therefore
It
should
of
the
the
the
A
dyes
value
...
ring
pyridone
process.
excitation
by the
for
the
reduce
on the
atom of
pyridone
in
The
effect
electronic
are
solution.
to
little
nitrogen
the
in
dyes
extinction
coefficient.
calculations
n-decyl
structure.
the
the
the
reduction
high
appears
exception
has
the
that
have
greens
extinction
groups
observed
presence
The
planarity.
the
involved
28).
Table
with
alkyl
indicates
the
therefore
more bathochromic
also
residue
dyes
state.
still
or
(149)
ethylene
show a general
dyes
blues
bright
and,
peaks"
dyes
Michler's
these
excited
azomethine
lower
such
indirectly
The "double
(179b)
dyes
for
although
such
pyridone
the
of
however.
is
the
chain
the
27 show that
aza analogues,
from
and,
than
polar
Table
Even
of
derived
solvatochromism
is
state
obtained
The dyes
systems.
(181a)
(179a),
PPP-MO calculations
assume planar
within
the
be the
be noted
ring
geometry,
may prevent
of
result
that
with
a
dyes
second peak to a shoulder
was
110
by a marked
accompanied
longer
wavelength
the
For
dye
(with
integral,
p-orbitals,
i. e.
ring
gave
values
been
standard
28 all
the
cyano
to
those
intensity
the
of
satisfactory
the
For
parameters
7.75eV
=
ascribed
were
used
and an electron
bond).
than
for
the
given
ring
of
amine
cyano
values
ethylene-derived
dyes
the
benzindole
VSIP = 17.75eV
of
that
and electron
(see
nitrogen
the
the
a primary
For
a
affinity
modified
the
of
The standard
other
available.
values
were
atom of
of
in
atoms
The nitrogen
Michler's
were
carbon)
a nitrogen
results
carbon
maximum overlap
22.5eV
for
the
assumes
2,3-double
a quinone
previously
which
a VSIP of
being
values
molecular
affinity
Table
structure.
reported136.
the
system
relative
of
-2.4eV,
a planar
more
in
exception
B, of
directly
attached
have
the
was given
(these
the
peak.
resonance
10.8eV
in
PPP-MO calculations
molecule
pyridone
increase
Section
2.1.3.2).
The calculated
agreement
reasonable
suitability
between
the
of
theory
the
with
ring
dyes
(179a)
previously
derived
and
(178a)
dyes
observed
(180a)
and
in
values
(181a),
VSIP and electron
with
the
confirming
the
adequacy
for
values
affinity
Thus the
Agreement
satisfactory
was also
in
are
toluene.
was demonstrated.
parameters
and experiment
benzindole
for
values
max
the
of
the
benzindole.
To examine
representative
PPP-calculated
density
changes
Relevant
and
12.
values
Figs.
characteristics
donor
nitrogen
the
dye
pyridone
state
ground
for
the
11a and
of
the
atoms
in
systems
various
12a show the
typical
carry
a net
dyes.
positive
in
process,
absorption
and n-electron
bands
absorption
(179a)
pyridone
light
the
and
(178a)
atoms
distributions
charge
visible
dyes
for
of
roles
relative
the
are
were
calculated.
summarised
in
Figs.
11
donor-acceptor
Thus,
in
charge
the
ground
and the
state
pyridone
the
111
Fig.
11:
(a)
Ground
for
changes
state
densities
charge
and (b)
ýN±
density
of dye (178a)
transition
the visible
n-electron
33
+.025
10
-.
-104
+.034
+,041
076
-.
I+.
12
+.033
025
-.
078
_.
-104
+.034 +028
N-.377
LW
/C+
f.A1
+048
N
+. 144
-. 090
+"107
+242
N1
0
539
-
+. 239
\n
521
-.
(a)
N! o31
+.022
-04
020
-.
+104
+.035
031
-.
+. 371b
309
-.
02
-.
-045
N
+. mo
+.021
_.
/N-"039
+. 075
+. 034
26
136
+.1ý7
119
-.
+. 008
00
- "0038 0
-.
036
+.
078
+. 014
0.039
(b)
A
ma,.
(calc)
589nm
=
(toluene)
607nm
=
Amax
112
Fig.
12:
(a)
Ground
changes
state
for
densities
charge
the visible
+. 004
+. 021
0.0
+. 053
and (b)
transition
density
n-electron
of dye (179a)
072
+.
+. 026
N+ 479
.
053
-.
0.0
049
-.
128
-.
+. 008 +08
N-. 377
+. 097
+-124
-1,11
.
+. 241
O
+.2 38
N
+. 54
+. 268
099
0
+. 296
+-52
(a)
060
046
+.
+.053
+. 026
N-. 066
0.0
0.0
+. 098
+. 125
+ 025
+. 038
+ .094
0.0
4
-"14
046
jN-.
141
-.
C
Oro
-. 114
0.0
0.0
+. 103
N
0"
ý0
0.0
054
-.
062
-.
(b)
Amax
(caic)
643nm
=
(toluene)
659nm
=
A
max
carbonyl
n-electron
transition
and cyano
groups
have
density
charges
for
[Figs.
11(b)
and
charge.
However
longest
wavelength
electronic
show that,
rather
a net
the
12(b))
negative
than
the
the
electron
113
density
being
lost
sites
the
atoms
between
the
two
This
in
that
electron
density
in
the
ring
2.2.3
on the
Stability
and the
results
is
It
that
the
to
the
bridge
nitrogen
of
decomposition
total
test
-
up of
(178c)
types
(178)
-
2.2.1.4
more
and
(180c)
into
the
dye molecule
in
and
be slightly
(180b)
dye.
the
of
decrease
dyes
dyes
Section
to
appear
stability
(180a),
lack
stability
poor
bridge
(180b)
and its
29.
(180a),
a nitrogen
in
described
the
of
and azomethine
methine
Table
dyes
a marked
of
(181)
and
photochemical
causes
(178)
show generally
(178b)
analogous
incorporation
detrimental
thermal
is
the
Moreover,
and
stability
is
(180c)
suggesting
observed
under
the
conditions.
With
bridged
the
the
than
dyes.
in
dyes
(178a),
Dyes
lightfast
the
that
that
at
build
process
resultant
procedure
summarised
are
evident
properties.
using
is
largest
absorption
the
of
the
nitrogen
involvement
minimal
Dyes
of
properties
assessed
were
the
the
of
as it
the
and acceptor
the
of
small
state.
light
the
acceptor
bridging
the
at
the donor
shift,
predict
the
at
and a relatively
importance
bathochromic
Properties
The stability
(181)
A...
dyes,
from both
major
reveal
in
nitrogen
influence
of
lost
excited
also
the
of
the
and gained
up predominantly
MO calculations
The calculations
pyridone
built
is
a large
the
residues
extremities
explains
inducing
position
is
density
electron
heteroatoms.
donor
the
density
electron
amount of
bridge
from
the
dyes
opposite
are
to
tests
stability
(179b)
benzindole
and
(179c)
of
less
photochemically
that
observed
indicate
the
that
longer
(179)
with
for
the
stable
dyes
the
and
(178)
carbon
N-substituted
(181)
than
the
their
and
carbon
aza analogues,
The thermal
(180).
bridged
chain
dyes
is
(179a),
on the
114
Table
29:
Stability
properties
Dye
of
dyes
(178a)
-
Photo stability
(% loss)
(148)
(181c)
Thermal
stability
(% loss)
8
5
(178a)
38
63
(180a)
39
(178b)
43
(180b)
44
(178c)
57
(180c)
58
Standard
(179a)
Total
Decomposition
Total
46
Decomposition
Total
65
Decomposition
Total
27`"'
Decomposition
9ca)
(181a)
58(10'
43 (8k)
51
14(b)
(179b)
(181b)
36ca>
33cb'
(179c)
40
(181c)
35
(b)
hypsochromic
the
for
more
- values
dye
the
by
exhibited
pyridone
azomethine
is
true.
then
the
analogues
less
of
the
two
absorption
peaks
of
the
two
absorption
peaks
was accompanied
film
acetate
likely
(181a),
the
(181b)
Decomposition
38
(a)
decomposition
total
and the cellulose
40c"'
11cb)
Total
bathochromic
for
the
more
- values
dye
by
the
exhibited
(c)
Decomposition"--)
Total
46
47
dye
is
and
by carbonisation
to
be heat
(181c)
the
stable.
reverse
of
the
For
situation
dye
the
115
2.3
OXOCARBON DYES
2.3.1.1
Squarylium
Squaric
give
(53)
acid
carboxylic
Dyes as Potential
acids,
will
substitution
for
with,
aromatic
amines138.
(182)
give
for
and,
undergo
HO
nucleophilic
pyrrolesS8,
all
example,
and primary
species
pyrroles
(62),
OH
is
product
N, N-dialkylarylamines
(183).
give
amines
R3
been
and tertiary
azulenes137
give
and secondary
like
to
have
reactions
a 1,3-disubstituted
cases
and,
addition-elimination
Such condensation
example,
In
Absorbers
as an electrophilic
products.
reported
formed,
behaves
Near-Infrared
R4
R4
R3
I
+
R2
ýý
N
I1
N
R1
OO
(53)
R2
0
R
(62)
0
R
R
+/
N
N
R'
(182)
0ýN\
NIR
R0
(183)
to
According
donor
will
band.
substituted
cause
Dewar's
rules
at a starred
a pronounced
Further
based
site
bathochromic
bathochromic
shifts
on PMO theory
a strong
hydrocarbon
in an odd-alternant
shift
are
also
of
the
obtained
electron
first
absorption
if
electron
116
withdrawing
from
residues
(184)
are
placed
dyes
squarylium
at
As can be seen
sites.
isoconjugate
are
with
an odd-alternant
or
*o
R
unstarred
o*R
0
ýOD
\l/
ý*
R'
'ý
*R'
ii*
o
0
(184)
hydrocarbon
0-
central
It
at
dyes,
is
which
possible
of
the
Dewar's
are
for
generally
displace
to
of
system.
can be applied.
rules
and the
position
accounts
region
near-infrared
termini
a starred
positions
unstarred
these
and thus
system,
highly
the
blue
the
(A
visible
the
spectrum
For
example
bathochromic
max
ca.
band
the
Ph
Ph
0
Ph,.,
I
Ph0
+/
CH-
CH
Ph
0
0
(185)
tBu
t Bu
CH
CH
S
I
t Bu
tBu
(186)
character
into
electron
and thiopyrylium
pyrylium
Ph
two
of
650nm).
absorption
by modifying
the
C=O at
central
The
the
donor
117
(185)
systems
dyes
tend
thus
it
to
and
(186)
absorb
have
lower
stability
was of
to
examine
to
if
dyes
in
2.3.1.2
Synthesis
(182)
Previous
that
the
see
unpublished
arylamine
infrared
the
beyond
types
arylamine
modification
Such
the
of
700nm could
(182),
and
arylamine
be prepared.
of Dyes and Intermediates
by Griffiths
work
to
squaric
to
acid
dye
This
absorbing.
had demonstrated
and Bello
2,2-dihydro-2,2-dimethyl-lH-perimidine
system
be condensed
could
than
interest
residue
810 and 920nm respectively.
at
dye
the
give
intensely
absorbed
(187)
(188),
which
800nm
at
was
in
0
H
H
\
N
H
1+
ry
Me
N
Me
Me
/Me
Me
Me
N
/N
H
H
H
(187)
(188)
dichloromethane,
these
However,
because
of
and exhibited
of
highly
investigated.
The synthesis
to
the
establish
to
try
(123e)
-
listed
in
It
of
boiling
removal
azeotropic
other
the
enhance
(188)
of
of
absorption
were
work
was
not
was therefore
derivatives
solubility
between
relationships
The condensation
effected
of
As this
value
the
dyes,
and to
wavelength,
stability,
structure.
and chemical
in
derivatives
practical
dye.
the
of
little
of
were
nature
further
nature,
a preliminary
examined
insoluble
band width.
absorption
properties
advantageous
the
a narrow
(123i)
squaric
of
30.
found
was
that
The dihydroperimidines
water.
14,
the
under
mixtures
n-butanol/toluene
(Table
Table
with
acid
dihydroperimidines
Section
dyes
of
1.2.1.2).
type
(189)
of
conditions
used
The resultant
which
was easily
possessed
were
(123a),
dyes
shorter
are
R
118
Table
30:
Near-infrared
dyes
dihydroperimidine
absorbing
based
squarylium
0
H
\+
/H
NR
'<Rl
R
H'
N
H
(189)
Structure
R
(189a)
-Et
(189b)
chains,
polar
(189e)
i. e.
(189f)
residues
(189d)
and
the
was
(189c)
still
-
most
(189f)
appreciable
in
gave
universally
their
soluble.
isolation
than
(189a)
in
dyes
With
and
more non-
incorporation
that
the
(189f)
However
solubility
enhanced
Of the
ligroin.
and
substituents.
at
a greatly
significantly
(189c)
solvents
was found
It
exhibit
Dyes
chain
dihydroperimidines
(189e),
not
(188).
to
longer
as toluene.
into
even
solvents,
the
lacked
did
on organic
soluble
due to
such
solvents
aromatic
dyes
more
-C2H5COOC4H9
(189b)
and
when compared
solubility
and
(189a)
namely
undoubtedly
polar
`
-Me
considerably
(189c)
-CO `
-Me
(189f)
(189b),
-CH2CH(CH3)CH2CH3
`/
(189e)
were
-CH2CH(CH3)2
-Et
(189d)
enhanced
-Et
-Me
(189c)
and R'
R'
to
2-position,
solubility
in
in
Table
listed
the
was more difficult
of
give
non-
more soluble
as they
30,
dyes,
did
119
not
under
that
led
vacuum,
by using
(n-butanol
layer
the
dyes,
squarylium
Not
light
pure
were
dye.
This
except
where
then
in
(190)
thus
(191)
and
proceeded
water
the
washing,
60 column
gel
was followed
for
toluene
the
all
other
otherwise.
(189a)
(189f)
-
to
the
vary
showed very
structural
similar
variations
the
of
position
further.
band
were
dyes
was found
with
down a silica
procedure
an attempt
(124)
The dihydroperimidines
2.1.2.1
After
directly
stated
it
even
synthesis
by washing
More pronounced
properties.
examined
absorption
the
all
the
n-butanol
miscible).
water
removal,
However,
be removed
and passed
surprisingly,
absorption
of
could
totally
be dried
could
instead
alcohol
not
Solvent
solution.
reaction
some dye decomposition.
to
the
is
obtain
the
n-propanol
but
as well,
to
from
precipitate
examined.
respectively.
and
dyes
The expected
Reaction
in
described
(125),
have
(124)
of
Section
the
structures
squaric
with
acid
oh""0
/\
\
OEt
N/
EtO
o
\/N
(190)
o-
H
H
N
CH3
H3C
0
N
0
0
(191)
gave
crude
a dull
red
product
a pigment
having
the
Unfortunately
than
solid
crystalline
A
a dye.
on cooling
in
541nm
=
max
dye proved
This
highly
lack
the
of
hot
reaction
mixture,
the
dime thy1formamide.
insoluble,
more closely
solubility
to
due
be
may
resembling
the
120
presence
intra-
of
the
dye
in
a pure
crystal
between
acid
proved
were
formed.
thus,
after
of
This
column
A
having
to
and
separated
fractions,
green
dichloromethane
in
753nm
=
and
the
atom bombardment
and fast
failed
fractions
Amax
having
products
chromatographic
in
788nm
=
max
component
and squaric
absorbing
two major
afforded
microanalysis
on both
spectrometry
out.
(125)
no product
mixture
n-propanol,
retained
Unfortunately
reaction
the
component
strongly
more
the
confirm
same
mass
of
structure
the
(191).
as
In
of
was carried
solvent.
dye
the
ion
tentative.
must remain
infrared
although
dye
atom
molecular
dihydroperimidine
complex,
On cooling
(190)
within
the
fast
Even
a detectable
give
structure
tetracyclic
the
eluted
to
bonding
isolate
to
possible
purposes.
failed
assigned
removal
first
not
characterisation
relatively
separation
the
the
was thus
It
spectrometry
and thus
Reaction
the
for
state
bombardment
peak,
as well
matrix.
hydrogen
as inter-molecular
to
addition
squarylium
was obtained
reaction
boiling
removal
absorbed
compared
of
dyes
dihydroperimidine
the
were
as metallic
at
to
water.
It
crystals
the
dyes
Et
\+
under
of
type
wavelength
the
with
conditions
[A
0
acid
squaric
(192)
in
azeotropic
The dye
max(CH2Cl2)
blue
Et
Me
Me
(192)
slow
relatively
of
types
dye
squarylium
bright
and was
(189),
other
by microanalysis.
was characterised
short
from
(120b)
mixture
surprisingly
the
Thus,
1-ethyl-2-methylperimidine
n-butanol/toluene
of
squarylium
synthesised.
green
dyes,
595nm]
=
in
colour.
a
121
Two additional
novel
near-infrared
and
(194)
and
1-decyl-2(1H)-methyl-benz[c,
acid
were
obtained
respectively.
absorbing
by condensing
successfully
d]indolium
Problems
were
Michler's
iodide
in
encountered
dyes
squarylium
(158)
Me2N
ethylene
with
achieving
(193)
squaric
efficient
NMe2
0
+
CH
CH
0
Me2N
(193)
Dec
ý --\N
Dec
ND
(194)
formation
of
(193),
reactions
of
the
proton
source
by isolated
in
Thus
2.1.3.1).
small
just
amounts,
acid-mediated
various
acid
itself
Consequently
the
sufficient
for
squaric
and for
by mass spectrometry,
highly
was
(194)
bathochromic
most
had
it
to
German
preparation
of
in
soluble
of
the
side
providing
dye could
a
only
and
spectroscopic
find,
Patent
this
several
had recently
dye139.
range
a wide
squarylium
in
900nm
=
max
a
disappointing
a West
the
measurements.
Dye
the
ethylene,
Section
very
characterisation
stability
Michler's
(see
due to
apparently
toluene.
months
been
of
in
dyes
synthesised
It
was therefore
after
synthesis
granted
and was
solvents
covering
of
this
the
this
dye
work.
that
122
2.3.1.3
Light
Absorption
light
The
absorption
in
measured
in
toluene
calculations
31:
Table
For
data
comparison
for
with
are
were
molecular
orbital
solvent.
dyes
new squarylium
Emax/lmol-'
(CH2C12)
m. x/
(CH2C12)
(Toluene)
were
coefficients
non-polar
A
dyes
results
extinction
as the
Dyes
squarylium
and the
Molar
was taken
Spectroscopic
Dye
A.,..
/nm
A
(CH2C12-Tol)
cm-'
(189a)
805
808
155,000
-3
(189b)
803
807
136,000
-4
(189c)
806
807
128,000
-1
(189d)
809
817
135,000
-8
(189e)
805
813
148,000
-8
(189f)
800
807
189,000
-7
(192)
595
603
151,000
-8
(193)
809
809
169,500
0
(194)
884
900
161,500
-16
low
be
slightly
may
dicloromethane
(a)
and toluene,
dichloromethane.
Squarylium
the
of
31 and 32.
Tables
the
of
properties
dichloromethane
in
summarised
recorded
Properties
(189e)
and
(189d)
and
does
dihydroperimidine
intramolecular
(189f)
absorb
that,
2-position
on the
effect
value
evident
on the
substituents
little
is
31 it
From Table
at
dyes
hydrogen
A
as would
of
the
similar
show very
longer
slightly
be expected,
dyes.
wavelengths
of
the
the
systems
has
(189c)
-
The benzoyl
than
in
varying
(189a)
Thus
properties.
and this
toluene,
bonding
solubility
dye
the
of
dihydroperimidine
the
of
values
max
in
low
due to
the
dye
other
due
to
be
may
NH proton
to
the
carbonyl
group.
The dihydroperimidine
which
is
to
be expected
dyes
for
show only
symmetrical
small
solvatochromic
squarylium
dyes.
effects,
Thus neither
123
the
ground
or the
state
has a permanent
state
excited
as shown
by PPP-MO calculations.
The perimidine
ethylene
dye
dye
small
(193)
and benzindole
solvatochromic
(192)
Dye
analogous
absorbs
a notably
dihydroperimidine
dyes
dichloromethane.
the
based
dihydroperimidine
(see
significantly
at
(192),
'H-n.
m. r.
were
is
Fig.
with
compared
13:
Michler's
exhibited
only
in
bathochromic
than
and attempts
to
if
that
of
visible
dye
Abscr'tiom
spectra
dichloromethane
absorption
curve
of
as shown in
(192)
the
to
(192)
the
about
of
structure
solubility
dyes
than
the
obtained
Fig.
(189d)
and
dye
13,
the
should
be
dyes,
dihydroperimidine
of
(189d),
chromophores
that
doubts
the
azo dyes
simple
was applied
analogous
confirm
in
these
predicted
raises
low
by the
the
fact
the
wavelengths
The PPP-MO method
and this
hampered
as in
longer
at
blue
when the
surprising
absorbed
than
wavelength
considered,
This
However
solvents.
(192),
similarly
an intense
giving
experiment.
with
structure
dyes
32)
more
variance
are
analogues.
Table
shorter
somewhat
2.1.2
Section
perimidine
problem
is
This
in
dye
moment,
effects.
at
discussed
(194)
dipole
assigned
(192)
in
by
organic
for
(192)
the
in
C
1;
A
(192)r
a:
1
J
.
S. l. ý
C. t"i
HI
0 l1
_
wavelength
A-
P; o Ll
absorbance
/ nm
f').:.
vv
Qk,e ee
.
124
in
similarities
that
suggesting
shape
between
the
(192)
does
least
at
two
are
apparent,
fundamental
the
contain
strongly
squarylium
chromophore.
The spectrum
generally
the
of
The band
that
(193)
infrared
have
dyes
squarylium
absorption
in
absorbance
the
absorb
and are
thus
of
region
of
32.
The VSIP
values
dyes
used
of
latter
absorption
maximum
typifies
curve
symmetry.
and benzindole
ethylene
effective
particularly
is
tail.
wavelength
absorption
Michler's
dye
which
visible/near-infrared
electronic
are
the
the
one of
as
bathochromic
most
seen
A
1 at
ca.
the
the
low
very
in
31,
Table
except
an
giving
solutions
(192)
of
and
(194)
dyes
the
all
laser
gallium-aluminium-arsenide
emission,
potential.
and the
benzindole
values
were those
residue
are
results
affinity
and the
2.1.2.2
dyes
squarylium
representative
of
and electron
Section
absorbing
max.
exception
the
in
the
dyes
the
human eye
the
13 is
Fig.
Thus,
region.
to
of
from
infrared
the
of
spectra
and perimidines
in
for
of
PPP-MO method,
dihydroperimidines
monoazo
can
spectrum
by the
calculated
be
practical
The absorption
the
as the
type
31 the
of
visible
with
the
in
increases
respectively
colourless
Furthermore,
dyes,
squarylium
by a weak shorter
This
Table
the
synthesised.
as
value
in
peak
degree
feature
dyes,
were
sharp
peak
and the
yet
An attractive
Table
from
absorbers,
(192),
main
a high
(194)
and
squarylium
of
wavelengths.
be seen
As can
typical
accompanied
the
of
longer
systems
dyes
spectrum
width
to
moves
is
an intense
exhibit
region
(189d)
of
summarised
used
for
VSIP and electron
were
in
the
for
developed
those
were
described
the
affinity
in
Section
2.1.3.2.
In
(192)
general
being
the
calculated
a notable
results
exception.
agreed
The slight
well
with
dye
experiment,
overestimation
of
the
125
Table
32:
Comparison
maxima
Ä,
Dye
of PPP-MO calculated
and
representative
squarylium
of
A
a=.c/nm
(Calc)
experimental
dyes
AA, ýsx/nm
(Tol-Calc)
m=x/nm
(Toluene)
absorption
Oscillator
strength
(f)(Calc)
(189a)
769
808
+39
1.97
(189d)
774
817
+43
2.00
(192)
936
603
-333
1.84
(193)
834
809
-25
1.50
(194)
958
900
-58
2.60
absorption
fact
the
maxima
that
certainly
not
is
It
of
the
case
these
with
(194)
and
PPP-MO method
assumes
dyes,
may be partly
a planar
to
attributed
geometry,
is
which
as shown by molecular
models.
A...
interest
that
dye
that
than
(193)
the
uncharacterised
less
dyes
of
the
(191)
calculated
calculated
was 739nm.
Thus
for
2,2-disubstituted
typical
this
the
predicted
0-
H
\+
for
value
is
value
analogues.
H
CH3
H 3C
0
0
(191)
Thus
the
MO-calculations
fractions
blue-shifted
changes
presented
for
visible
Figs.
desired
state
ground
the
in
obtained
may be the
chromatography
Calculated
support
charge
absorption
14 and
the
from
argument
that
the
reaction
product
(191).
15 as typical
mixture
and the
densities
bands
one of
for
data
dyes
for
the
two
via
column
n-electron
(189a)
and
infrared
density
(194)
are
squarylium
systems.
From Figs.
14 and
15 the
high
polarity
of
each
half
of
the
molecule
126
Fig.
14:
(a)
Ground
state
for
changes
densities
charge
the
first
(b)
and
band
absorption
dye
of
densit,
n-electron
(189a)
601
-.
0
20
-.
+. 054
+. 647
N
+. 21
096
-.
-11
+045
N
-"041
19
-.
s7
N+. -.
07
-.
11
Ný
0
576
-.
-. 22
+.22
(a)
06
-.
0
os
059
+.
-.
+. 01
012
-.
02
-.
08
-.
N
+"02
o.o
N
04
-.
0.0
/-
.
-_034 +.011
Ný
059
(b)
A
(c
max
a1c
=
768nm
=
808nm
A
max
in
the
from
state
ground
the
molecule
donor
is
that
Figure
zero
are
electron
the
other
14(b)
in
density
is
rings
particularly
conjugation
on excitation,
lose
electron
dipole
The overall
as would
changes
density
electron
with
groups.
however,
direct
density
apparent,
nitrogen
The electron
in
is
(toluene)
being
removed
moment of
the
be expected.
for
the
because
intriguing
with
the
whereas
density.
dye
dihydroperimidine
squarylium
the
nitrogen
the
ring-
nitrogen
appear
atoms
(189a)
atoms
to
attached
gain
to
127
Fig.
15:
(a)
Ground
state
for
changes
the
densities
charge
first
(b)
and
band
absorption
density
n-electron
dye
of
(194)
-. 004
+, 245
+-04
+. 003
04
001
-.
- .
05
-.
039
-,
0.0
+. 04
-"09
002
--587
N+.56
\
N
231
+.
+. 11
oý
5ý9
-.
0.0
.
017
+. 003
(b)
Amax
958nm
=
(calc)
Amax (toluene)
Figure
nitrogen
benzindole
2.3.1.4
15(b)
shows
and a build
aromatic
Stability
are
procedures
summarised
standard.
up of
the
the
benzindole
squarylium
and
rings.
described
Table
of
of
properties
in
in
density
electron
from
density
electron
of
Properties
The stability
the
a loss
900nm
=
the
previously
33.
Dyes
Squarylium
squarylium
in
The thiazole
Section
dye
dyes
were
2.1.2.4
(148)
assessed
and the
was taken
using
results
as the
128
CI
N
NEt2
02 Ngý
(148)
33:
Table
Stability
Dye
Standard
5
(189a)
62
47
(189b)
91
60
(189c)
92
62
(189d)
85
38
(189e)
73
17
(189f)
83
55
(192)
9
8
(193)
54
59
(194)
14
22
to
alkyl
(189b)
best
standard,
poor
dye
substituted
substituted
in
decrease
The aryl
other
the
particularly
The diethyl
(189e)
Thermal
stability
(% loss)
8
exhibited
general
dyes
squarylium
Photo stability
(% loss)
(148)
Relative
the
of the
properties
stability
overall
Dye (192)
Thus
markedly
for
thermal
and
practical
more stable
(189e)
dyes
appear
application
than
the other
of
show a
length.
(189d)
than
stabilities
would
to
chain
lightfastness
and better
(189d)
alkyl
stable
most
tended
squarylium
better
dyes,
properties
is
with
significantly
(189c).
and these
increasing
stabilities.
be the
to
appeared
dihydroperimidine
dihydroperimidine
and
(189a)
dyes
squarylium
and thermal
photochemical
dihydroperimidines,
substituted
exhibited
dihydroperimidine
the
and
the
than
dyes
to
possess
the
purposes.
dyes in Table
33.
IL7
is
This
not
surprising
dye
squarylium
system,
This
attack.
is
which
best
the
the
indicating
2.3.2.1
does
and,
infrared
cellulose
acetate
presence
highly
dyes listed
dyes
in
the
exhibits
best
in Table
Table
1 hour
after
(194),
the
absorbing
films
dye
(189e),
of
the
chemical
(194)
Thus
exception
all
to
for
true
series.
decomposition
of
has
at
33.
33 showed a
190°C
products.
been
recently
when it
because
hold
becomes
the
Dyes
(75)
acid
the
the
the
The Croconium
enamines
in
tests,
the
dyes
however
not
with
the
of
it
susceptible
stability
Croconic
i. r.
less
thermal
of
yellowing
the
more hypsochromic
the
cases
most
bathochromic
most
stability
In
in
statement
lightfastness,
thermal
as,
is
bathochromic
reacted
with
dyes
the
produced".
of
interest
of
heterocyclic
certain
(195)
formula
general
of
as a source
are
H
OH
0ý
0
(75)
0"'
CH-C
C=CH
ý
\\
ý-N
N
0
o'
R
R
(195)
As with
the
5-membered
and
positions.
Thus
ring
two
system,
squarylium
is
(196)
if
there
electron
Dewar's
is
considered
a strong
accepting
rules
then
carbonyl
Dewar's
of
then
electron
predict
bathochromic
highly
terms
in
can be explained
croconiums
theory).
site
the
the
it
is
donor
groups
(i. e.
rules,
at
a bathochromic
at
PMO
in
that,
evident
(-0-)
of
nature
the
a starred
two unstarred
shift
for
both
130
oC=CH
CH-C
00°
/0
f
\\
Ný
00I
RR
(196)
types
of
perturbation,
large
exceptionally
Although
about
the
fact,
to
spectral
and this
the
both
to
the
define
the
Croconic
this
with
acetic
give
(199)
Treatment
for
of
synthesis
dyes
the
of
and to
dyes.
In
I
the
of
dyes.
was undertaken,
system
define
known
literature"
open
croconium
dyes,
is
these
of
the
the
properties
in
a 5-step
red
in
limitations
the
with
of
chloranil
(197)
acid
of
salt
with
as a pale
from
resulted
chloranil,
was heated
(198).
in
yellow
as
sodium
with
Treatment
of
demethylation
to
The tetrahydroxy-p-benzoquinone
active
barium
as an insoluble
state
starting
crystals.
oxidised
the
anhydrous
synthesis
acid-hydrobromic
and addition
of
Thus
the
tetramethoxy-p-benzoquinone,
as deep
acid
in
was obtained
give
was then
croconic
little
very
in
Japanese
various
Dyes and Intermediates
Scheme 2772.140.
methoxide
solution
a range
squarylium
powder
to
(199)
details
of
of
acid
hygroscopic
in
appeared
the
procedure.
Synthesis
shown
media,
in
result
practice.
in
cited
and synthesis
spectroscopic
the
with
been
often
has
one paper
in
observed
recording
no experimental
synthetic
2.3.2.2
optical
preparation
comparison
have
to
reinforce
shift
characteristics,
only
gave
Thus
dyes
with
date
effects
bathochromic
croconium
dealing
patents
and these
manganese
chloride
yellow
warm dilute
gave
crystalline
sulphuric
dioxide
the
in
barium
solid
acid
alkaline
salt
(200).
for
of
131
0
0
cl
NaOMe /
MeOH /
H3CO
Heat
OCH3
0,00
tII
c"
H3CO
OCH3
Y
0
(197)
0
(198)
/
HBr(aq)
Heat
0
HO
acetic
0p2
H
i.
H
/
acid
H
NaOH /
ii.
H2O /
HC1(a) q/
Mn02
0
BaCl 2(aq)
Bam; H2O
"'ýp
0
0
(199)
(200)
i.
ii.
iii.
Dil
H+ / Heat
Remove water
Slurry
with
acetone
OH
HO
0
ý0
0
(75)
Scheme 27
35-40
of
free
hydrated
for
followed
minutes
croconic
discovered
that
anhydrous
croconic
anhydrous
nature
which
equivalent
acid
triturating
acid
of
showed
carbon
the
and inefficient,
the
with
acetone
product
was confirmed
one peak
croconic
at
rapidly
by
method
it
high
at
The
yields.
13C-n. m. r.
peak
was
gave
178ppm corresponding
(the
the
gave
whereas
in
crystals,
acid
a solution
The literature
tedious
tar
gave
evaporation
tar.
yellow
of
sulphate
by rotary
removal
as pale
only
atoms
barium
of
as a yellow/brown
was both
this
clearly
Water
acid.
croconic
purifying
by removal
(Fig.
to
40ppm is
16)
the
due to
132
Fig.
16:
13C-n. m. r of
! 00
10o
Ip
anhydrous
40
170
100
IN
croconic
110
120
110
100
acid
pp
10
be
p
N
30
30
0
10
b
DMSO).
The result
produce
croconic
was rather
as the
acid
as the
surprising
trihydrate
OH
literature
methods
all
(201).
OH
3H.
20
.
0ý
0
(201)
The reactions
nucleophile
examined
of
used
using
croconic
reaction
with
acid
occurred
acid
successfully
similar
n-propanol/toluene
that
croconic
substituted
derivatives,
derivatives
(202).
squaric
conditions
azeotropic
was less
with
with
reaction
simple
that
the
with
removal
reactive
than
types
various
of
acid,
Section
2.3.1.2
(i. e.
refluxing
in
of
It
water).
squaric
acid,
was noted
and no
N, N-dialkylarylamines
or
their
is
of
their
with
the
Nom'
OH
(202)
exception
were
3-hydroxy
133
The first
from
prepared
dye to be synthesised
croconium
3-hydroxy-N,
was thus
N-diethylaniline.
the dye (203),
The product
was purified
oý
Et2N
NEt2
O.
H
(203)
by column
chromatography
decompose
the
dark
(A
brown
dye)
crystals,
(204)
and absorbed
as aluminium
8-hydroxyjulolidine
by microanalysis.
at
particularly
readily
in
a similar
long
to
formed
It
wavelengths
to
the
enhanced
of
planarity
oý
+N
from
manner
by microanalysis.
and was characterised
due
tended
oxide
dichloromethane).
was obtained
be expected,
60;
gel
and was characterised
822nm
in
=
max
Dye
(silica
the
As would
chromophore
dye
this
o
'-
ý\/N
0-
OH
Hd
(204)
even
at
absorbed
This
CH2C12).
kinetic
study
was of
to
temperature,
determine
the
of
is discussed
occurred
to
suited
particularly
characteristics
Such a study
process.
condensation
particular
in
854nm
=
as it
interest
and was thus
the
(
(203)
than
wavelengths
reaction
room
at
readily
longer
Amax
acid
croconic
later
a
in Section
2.3.2.5.
(205)
Dye
from
acid.
hot
the
It
was obtained
of
reaction
proved
highly
dimethylformamide)
inefficiently
as pale
yellow-brown
with
N-4-3-hydroxyphenyl)morpholine
insoluble
and thus
in
common organic
satisfactory
croconic
solvents
purification
crystals
(even
could
not
in
be
134
OH
HO
r--ý
,
0
ýö
(205)
The dye gave the
achieved.
M+1 ion
expected
peak by FAB-mass
spectrometry.
The synthesis
of
croconium
N, N-dialkylanilines
this
has
was investigated.
3-acetylamino-N,
dyes
been
not
from
3-acylaminoin
reported
The synthesis
N-diethylaniline.
dye
of
Although
NHAc
literature
the
(206)
the
and thus
from
was attempted
reaction
solution
NHAC
'
Et2N
NEt2
(206)
showed
an absorption
low
only
yield
reaction
mixture
the
of
case
which
overlap
ring,
has
of
peak
at
and could
not
resulted
in
845nm (in
the
acetone),
be isolated.
Prolonged
decomposition
of
the
dye was formed
heating
of
the
However,
product.
N-ethyl-7-propionamido-2,2,4-trimethyltetrahydroquinoline,
enhanced
the
isolation
nucleophilic
amino
nitrogen
the
of
because
reactivity
lone
pair
dye
croconium
with
electrons
(207)
of
was possible
the
the
CH3
CH3
CH3
H3C
+_
CH3
3
N\
Et
Et
CHNHN0ý
(207)
0 NHCOC2H5
enforced
benzene
using
in
column
in
135
purification
with
silica
bathochromic
with
an absorption
As mentioned
this
in
earlier,
Thus
enamines.
bathochromic
it
and the
to
appeared
(207)].
dye
The dye
acid
will
dye,
react
residue
i. e.
was examined,
give
occurred
chromatography,
on the
crystals
as
an
The reaction
by column
as brown
was obtained
heterocyclic
(158)
should
(208).
decomposition
slight
toluene.
with
enamine
croconic
was purified
suffer
900nm in
maximum at
bathochromic
the
with
dye was exceptionally
This
croconic
highly
combination
exceptionally
readily,
the
60.
gel
although
column
[as
did
and gave
the
expected
Dec\+
Dec
O-
N
H
H
4\4
pO
(208)
M+1 peak
by FAB-mass
bathochromic
2.3.2.3
with
Light
an absorption
Absorption
The spectroscopic
toluene
and
and dichloromethane.
only
data
of
the
the
Croconium
croconium
The results
are
Dyes
dyes
were
in
measured
in
summarised
of
moderately
can
inevitably
Dyes
34
Tables
In
fact
using
be near-infrared
(203)
and
(204)
whereas
solvatochromism.
it
croconiuzn
absorption
near-infrared
effecting
electron
powerful
be synthesised
solvatochromism
negative
for
useful
particularly
can be seen how the
34 it
Table
N, N-dialkylanilines.
that
of
35.
From the
is
Properties
was exceptionally
1000nm.
maximum near
properties
it
As expected
spectrometry.
donor
would
currently
residues,
seem that
such
every
system
using
as 3-hydroxycroconium
known procedures
will
negligible
positive
dye
absorbing.
exhibited
the
an almost
more bathochromic
As expected,
dye
dye
(204)
(207)
exhibited
absorbed
at
a longer
136
Table
34:
Absorption
/nm
AA
ý,,..
(CH2C12-Tol)
(203)
822
820
214,000
+2
(204)
854
853
203,500
+1
(205)
-
(207)
886
882'"'
-
-
900
1014(11'
-
186,300
than
strength
(203),
the
of
-
The extinction
were
high,
nature
have
shows
narrow
very
the
visible
17:
these
band
enhanced
it
donor
electron
a reflection
of
widths.
the
is
of
spectrum
- near-infrared
Visible
- near-infrared
dichloromethane
spectrum
of
dye
dye
a high
with
also
demonstrated
them,
record
extensively
coupled
characteristics
This
to
was possible
dye molecules
These
symmetry.
electronic
where
is
which
of
the
system.
coefficients,
extremely
delocalised
in CH2C12 and toluene)
(12: 1)
: acetone
demonstrating
julolidine
-14
-
hot
(very
low
DMF,
solubility
in
trichloroethane
measured
-
wavelength
Fig.
dyes
Ef.. x/lmol-'
cm-'
(CH2C12)
m. x/nm
(CH2C12)
(Toluene)
(208)
of
croconium
A
Dye
(a)
(b)
of the
spectra
lead
to
by Fig.
(203).
(203)
It
degree
dyes
that
17,
which
is
also
in
2.;
l.
6
1
_^
A
0.8
0.4
0. a
40 ,
00
5Cu3
0 /i
wavelength
A-
absorbance
601
Nk1
/ nm
ij
NUJ
rsnn
11 _
1i
Cl
137
that,
noteworthy
possess
minimal
visible
The PPP-MO method
spectra
of
was then
groups
to
applied
dyes,
dye
acylamino
carbonyl
between
(207)
and the
it
hydrogen
were
the
calculation
results
are
dyes,
to
the
the
of
in
summarised
eck. (203),
that
was assumed
bonded
dyes
croconium
400 - 700nm.
the
3-hydroxy-substituted
For the
analogous
dyes,
squarylium
absorption
representative
35.
Table
the
as with
two of
adjacent
and the
the
-OH or
croconium
-NH
protons.
35:
Table
Comparison
PPP-MO calculated
dyes
croconium
of
representative
A
/nm
ma,,
(Calc)
Dye
and
experimental
/nm
AA
ma.
(Tol-Calc)
max/nm
(Toluene)
Oscillator
strength
(f)(Calc)
(203)
833
820
+13
1.34
(207)
922
900
+22
1.26
(208)
1155
+141
2.26
(a)
trichloroethane
=
- solvent
from
can be seen
It
of
atom
were
and 7.75eV
17.75eV
described
those
(207).
and
dye
previously
of
overestimation
of
planarity
cause
will
the
loss
dye
(208)
are
chromophore,
ground
for
the
summarised
in
changes
value
may,
state
in
in
density
visible
absorption
Figures
18 and
nitrogen
This
be due to
the
value
max
parameter
benzindole
fact
and
the
than
2.1.3.2.
part,
steric
charge
A
affinity
the
Section
whereas
due to
planarity
of
The calculated
density
max
for
respectively
A
the
higher
much
VSIP and electron
in
theory
The calculated
being
the
between
good agreement
satisfactory,
this
For
value.
observed
values
was less
(208)
dye
(203)
for
(12: 1)
: acetone
35 that
Table
was found
experiment
for
1014(211'
for
values
the
n-decyl
assumed
group
crowding.
and the
bands
of
19 respectively.
n-electron
dyes
(203)
and
138
Fig.
18:
(a)
Ground
density
state
for
changes
the
first
+.123
121
-.
(203)
/
N
+.os1
ll\ý
dye
of
0 H%',
'
0
01
8
0?
-.
+.022
band
+.2!
+. 06
+. 09?
214
-.
n-electron
and (b)
absorption
44
-.
0
+. 2430/H
+. 3acºN
densities
electron
1
-022
(a)
-11
0.0 /H
000H
02 3
.
+. 16
022
+.
01
-.
OS
-.
+.02
+. o +5 N
/"
.
OS
-.
+. 04
0
02
+.016
(b)
A
max
A
max
is
From the
ground
apparent
that
Thus
the
the
nitrogen
transferred
state
shown
with
aryl
and
19(b).
this
narrow
notable
residues
also
the
absorption
Fig.
donate
three
complete
Thus
18(a)
=
820nm
=
(203)
carbonyl
degree
is
groups.
as
small
after
of
density
symmetry
a relatively
it
chromophores.
and electron
electronic
occurs
(208)
and
donor-acceptor
central
833nm
(toluene)
both
deficient
density
high
of
typical
electron
nearly
electron
from
are
have
previously,
synonymous
It
to
18(b)
of
redistribution
is
are
extensively
by Figs.
As stated
systems
atoms
The chrcmcphores
densities
charge
(caic)
electronic
electronic
excitation.
symmetry
is
bands.
that
a significant
the
hydroxyl
amount
of
group
electron
in
the
density
donor
to
139
Fig.
19:
(a)
Ground
density
state
for
changes
07N+
-.
`01
06
-.
+. 004
first
absorption
(b)
n-electron
band
dye
of
(208)
+.134
577
0
3
-.
06
04
-.
+. 015
the
and
35
-.
0
01
-.
0.0
densities
electron
1
01
-.
0
0.0
34
-.
+. 028
(a)
+.002 +01
04
-.
ö2
N
+.013
0.0
0,0
+. 022
035
+.
+. 032
+. 01
N
-. 01
01
-.
04
-.
+. O72
+. 001
09
.
(b)
A
max
(calc)
=
maxim
* measured
the
in
trichloroethane
ring
croconium
to
contribution
Fig.
electron
migration
acceptor
the
18(b)].
19(b)
it
density
of
is
is
electron
carbonyl
the
ground
density
as might
density
groups,
there
the
changes
interesting
also
not
but
state
1014nm
(12: 1)
: acetone
electron
[Fig.
excitation
In
in
1155nm
=
to
groups
make no
accompanying
note
that
the
electron
migration
be expected.
Thus,
donor
nitrogen
atoms
electron
density
from
is
the
a loss
of
rather
than
to
the
from
of
140
both
amino
the
aromatic
2.3.2.4
and carbonyl
a build
with
up of
density
electron
in
rings.
Stability
Properties
The stability
cellulose
groups
properties
film
acetate
the
of
by the
Section
2.2.1.4.
The results
monoazo
dye
was taken
(148)
the
of
Croconium
dyes
croconium
techniques
are
Dyes
described
in
standard
as in
36.
Table
in
assessed
in
previously
summarised
as the
were
The simple
previous
stability
tests.
N
`}-"
N=N
NEt2
`/
S/
02N
(148)
36
Table
: Stability
properties
in cellulose
acetate
Dye
Thermal stability
(% loss)
8
5
(203)
66
87
(204)
30
90
(207)
65
total
decomposition
(208)
21
total
decomposition
(148)
to
It
was not
possible
as it
was too
insoluble
Unlike
the
For
trends.
specific
usual
of
trend
the
dye
of
is
the
croconium
example,
decreasing
observed.
if
in
Section
dyes
do not
thermal
stability
with
stability
Thus
into
cast
discussed
the
of
properties
stability
be effectively
dyes
of
the
assess
to
squarylium
properties
stability
shift
dyes
croconium
Photo stability
(% loss)
Standard
the
of selected
films
2.3.1.4
is
increasing
stabilities
of
(205)
film.
the
appear
dye
the
to
follow.
any
then
considered
bathochromic
(207)
and
(208)
141
so low
are
that
acetate
film
whereas
the
the
during
(203)
the
(204)
lightfastness
dye
situation
dye
(190°C
were
rather
more
stable.
less
predictable
are
the
was also
found
cellulose
period
most
for
On the
and the
Surprisingly
(203),
julolidine-based
with
60 minutes),
stable.
than
was more photostable
normally
on the
test
properties
(208)
(204)
the
of
the
and
dye
julolidine
the
of
dyes
bathochromic
most
decomposition
occurred
hand,
other
total
the reverse
in
systems
other
dye classes68.
On the
the
whole
properties
and significantly
to
compared
the
of
analogous
squarylium
croconium
dye
heat
interesting
to
the
as imparting
also
lends
The mechanism
arylamines
formation
solvent.
No such
that
dyes
has
of
This
when
and that
of
Acid
been
then
investigations
and
would
have
been
infrared
other
appear
the
shift,
dyes
than
that,
those
as well
benzindole
of
(194)
residue
greater
of
the
Reaction
Condensation
Arylamines
acid
squaric
and shown to
half-ester
with
of
much better
It
between
reaction
reacts
the
is
It
stability
is
Mechanism
investigated6'"62,
a squarate
but
stability,
be expected.
perhaps
the
for
absorbing
shows the
counterpart.
(208)
dyes.
infrared
to
2.3.1.4)
photochemical
of
the
with
photochemical
squarylium
bathochromic
would
the
its
(208)
Section
observed
croconium
Croconic
of
33;
the
that
than
An Examination
Between
stability
properties
of
lower
than
however
itself
than
(Table
slightly
a significant
photostability
2.3.2.5
only
other
properties
(194)
better
for
obtained
stability
stability
squarylium
absorbing
thermal
poor
lightfastness
poorer
dye
note
significantly
(158)
the
have
to
much inferior
had very
standard.
A comparison
is
dyes
croconium
with
the
the
alcohol
(see
arylamine
undertaken
for
the
and tertiary
initial
involve
component
Section
analogous
of
1.3.5.1).
the
142
reactions
devised
with
to
croconic
try
condensation
and define
the
and thus
a series
parameters
that
of experiments
were
this
control
reaction.
When examining
the
8-hydroxyjulolidine
room
acid,
synthesis
of
and croconic
temperature
to
acid
(204).
give
dye
(204)
it
reacted
the
Unlike
that
was noted
in
readily
ethanol
corresponding
at
squaric
acid
(204)
reaction,
to
azeotropic
to
proceed
monitored
water
systems,
acids,
formation
of
the
reaction
very
useful
(204)
could
for
be
spectroscopy.
kinetically
was studied
was therefore
as the
particularly
for
was unnecessary
reaction
by absorption
readily
The reaction
of
This
completion.
studies,
mechanistic
solvent
removal
and the
on the
and base
catalysts
examined
by rapidly
different
of
effects
reaction
rate
were
equal
volumes
of
determined.
Solvent
effects
of
acid
croconic
cell
and held
the
A
at
the
of
max
time
conversion
Fig.
until
20 for
the
dye
taken
was
was then
to
(204)
almost
the
(204)
temperature,
moment of
an induction
occurred,
in
n-propanol.
at
mixing
in
while
the
reaction
rate
the
two
of
The gradient
at
time.
solutions.
little
which
commenced at
profile
quartz
absorbance
intervals
various
the
10m1 of
a 1mm pathlength
during
period,
and then
A typical
complete.
to
a
0.88x10-°mol
containing
8-hydroxyjulolidine
was measured
as the
reaction
of
in
8-hydroxyjulolidine
a solution
transferred
appropriate
showed
The reaction
rate
and
give
1.76x10-4mo1
The solution
solvent.
Zero
system
solvent
appropriate
to
mixing
of
and a solution
acid
croconic
of
solution
were
is
a steady
shown in
of
the
linear
143
Fig.
20:
Rate
formation
of
dye
of
(204)
in
n-propanol
30°C
at
2.4
2.8
A
1.2
P. o
5i W10
12 0 00+0
absorbance
part
the
of
reaction
(i. e.
curve
between
pure
n-propanol,
solvents
n-butanol,
dimethylformamide,
gradients
of
the
rate
constants
of
the
relevant
all
the
carried
Attempts
given
in
such
dissolve
-,
soluble
each
alcohol,
the
of
are
by the
n-hexanol
acetate,
low
time
period,
than
other
of
was not
any higher
recording
intervals.
solubility
it
Dielectric
The reactions
solvents
Thus
or
37.
Table
30 second
at
in
ethanol,
2-methyl-1-
listed.
a 30 minute
temperature.
ethyl
in
also
solvent
methanol,
The calculated
summarised
synthesis
hampered
in
in
are
dye
room
acid
croconic
in
out
37 were
at
isopropyl
30°C over
at
carry
solvents
those
croconic
possible
nor
alcohols,
dichloromethane,
toluene,
ether.
The results
significantly
to
namely
solvents
A..
at
Table
sufficiently
diethyl
as a measure
considered,
and acetonitrile.
curves
out
absorbance
were
n-pentanol,
propanol,
were
A and B) was taken
rate.
Initially,
in
; cº agCl
/ minutes
time
A-
24 0 3O
18.000
in
in
Table
37 show that
acetonitrile
or
dye
formation
dimethylformamide
does
during
not
occur
the
acid
to
was it
or
144
Table
37:
The rates
solvents
of formation
at 30°C
Solvent
dye
of
Dielectric
(204)
in
selected
pure
Gradient/absorbance
constant
E
per
units
second
methanol
32.7
0.15
ethanol
24.6
0.17
n-propanol
20.3
0.34
n-butanol
17.5
0.37
n-pentanol
13.9
0.38
iso-propanol
19.9
0.32
2-methyl-1-
17.7
0.45
dimethylformamide
36.7
0.00
acetonitrile
37.5
0.00
propano1
30 minute
for
time
5 hours
period
in
dark
the
could
be detected
occur
in
these
in
two
for
set
a small
Therefore,
solution.
they
solvents,
However,
experiment.
room temperature
at
each
this
far
are
amount
although
less
leaving
after
dye
of
does
reaction
than
effective
alcohol
solvents.
37 it
From Table
increases
decrease
first
At
in
dielectric
other
reactive
intermediate
example,
ethanol
constant
ethanol
dielectric
the
relative
in
to
to
ethanol
n-propanol,
constant,
such
appear
of
rate
this
dye
is
very
where
the
rate
the
as solvation
of
to
is
even
though
On the
large.
there
of
only
the
in
is
dye
the
methanol
to
to
the
increases.
or
of
enhanced
hand,
a much smaller
doubles.
a
For
reaction.
decrease
other
formation
rate
reactants
slightly
the
reaction
be related
length
a role
play
series
seem to
chain
formation
methanol,
in
would
the
alcohols
as the
constant
factors
However,
length
chain
sight
in
that
apparent
increasing
with
n-pentanol.
is
in
dielectric
in
on passing
in
decrease
It
is
from
145
that
probable
reactants,
in
be less
will
significant.
This
propanol
dielectric
is
constant
Steric
effects
solvating
As alcohols
in
alcohol
the
an inert
solvent
of
then
were
was examined
solvent.
These
of
of
(204)
were
high
intervals.
1 minute
It
is
clear
formed
dielectric
dipolar
from
over
This
the
aprotic
as the
out
as the
solvents,
are
in
part,
proportion
namely
polar
alcohol.
solvent,
aprotic
aprotic
to
n-propanol
give
90%, and the
the
of
rate
and toluene
water
time
intervals
1 hour,
over
of
to
case
in
of
water
the
of
because
of
the
of
dye
Table
water
dimethylformamide
38.
the
increases,
rate
no dye
until
50%
water
when
progressive
water
at
monitoring
summarised
the
systems
and acetonitrile
the experiment
of
period
for
chosen
protic
a non-polar
10% to
the
of
diluent
this
of
it
as before.
percentage
in
as a
process,
The alcohol
dimethylformamide
38 that
may be due,
constant
concentration
of
with
for
carried
Table
time
the
polar
from
The results
decreases
formation
present.
were
reactions
of
Various
30 second
at
the
-
effective
forming
a highly
was measured
For
less
dye
as examples
measurements
rate.
reaction
systems,
is
over
its
the
with
of
ranging
30 minutes,
become more
and n-pentanol.
even
conjunction
mixed
were
n-propanol
dye
n-butanol
rate.
as representative
solvents
The experimental
taken
in
examined
toluene
and
chains,
though
even
was n-propanol.
and acetonitrile
solvents,
proportions
in
influence
as an example
dimethylformamide
the
of
why 2-methyl-1-
explain
of
on reaction
experiments
aliphatic
effects
reaction,
that
solvation
or n-pentanol.
examine
co-solvents
formation
n-butanol
to
series
Water
than
important
interest
was of
of
clearly
are
help
also
rate
higher
than
species
longer
make 2-methyl-1-propanol
would
strong
and dielectric
would
highest
is
With
reaction.
effective
theory
the
showed
there
and ethanol
the
so retarding
solvation
this
methanol
is
in
increase
increased.
is
The
and acetonitrile
146
Table
38:
Relative
systems
formation
rates
of
at 31°C
Reaction
rate
water
toluene
$
n-propanol
co-solvent
(204)
of
in
mixed
solvent
of dye formation
units
sec-'
/ absorbance
dimethyl-
acetonitrile
formamide
(a)
(b)
(c)
(d)
(e)
100
0
0.34
0.34
0.34
0.34
95
5
0.311=1
0.33
0.0911-'
0.13
90
10
0.22(°'
0.33
0.064(-'
0.12(°'
85
15
0.19(-'
0.32
0.042(d)
0.10(d)
80
20
0.15("'
0.34
0.029(12'
0.09("'
50
50
0. OO(1.'
0.51
0.00
0.06(d)
25
75
0.53(a'
10
90
0.63(b'
-
also
in
recorded
recorded
recorded
recorded
recorded
to
appear
low
effect
there
From zero
observed.
little
in
mechanism
solution
is
toluene
the
case
the
any
medium
depresses
was noted
that
croconic
factor
in
acid
of
dye
from
300nm),
which
virtually
even when present
a different
as co-solvent,
20% toluene
in
the
formation.
50% to
alcohol
system
solvent
as the
However,
90% there
is
solvents
of
in
a marked
the
reaction
dielectric
constant
reaction.
the
which
was noticeably
colourless,
in-the
important
increases
that
rate
is
croconic
into
its
is
rate
reaction
more yellow
dissociation'of
due
the
to
be
to
was shown
is
reaction
toluene
of
rate
the
the
of
formation.
show that
and that
to
rate
increased
dye
of
rate
results
of
in
change
of
These
It
the
is
is
the
retard
In
increase
the
severely
proportions.
proportion
of
30°C
32°C
241C
26°C
25°C
at
at
at
at
at
in
acid
monoanion
colour.
low
the
This
Amyx
(
ca.
(A
ca.
m=x
147
370nm) which
unreactive
degree
is
in
Thus it
yellow.
the
condensation
of dissociation
is
probable
and thus
process,
of croconic
that
the anion
the
the lower
acid
is
the
greater
the rate
of
reaction.
The relative
toluene
- n-propanol
n-propanol
anion
degrees
21:
of croconic
can be seen
mixtures
below
proportions
50% is
the
from
Fig.
acid
in different
21.
Only
concentration
the
of
at
croconate
depressed.
appreciably
Fig.
of dissociation
UV/visible
spectrum
solvent
mixtures
of
croconic
in
acid
toluene
: n-
ropanol
a y.
Aa"
e. 4a
0.24
a. aa
A
(a)
(b)
(c)
- absorbance
5%
toluene
50%
toluene
90%
toluene
-
The effects
n-pr:
8-hydr
of
of
ac_d
or
addition
and,
was added
-scopically
of
450 00
404.00
358 ed
various
cuvette.
in
the
acids
on the
mixture
after
the
this
2cm3 of
to
the
way.
bases
and
are
and
acid
of
reaction
solution
was then
monitored
Relative
and 10%
90% toluene
one drop
reaction
summarised
in
this
confirmed
reaction
croconic
solvent
The reaction
usual
of
rate
comprising
mixing
in
reactants
spec,: -. -photometer
spec:.
and base
a solvent
xyjulolidine
base
wavelength
/ nm
acid
was used
panol
312.80
95% n-propanol
50% n-propanol
10% n-propanol
Thus
suggestion.
266 00
a solution
rates
Table
in
a
for
39.
the
148
Table
39:
The effects
(90% toluene
Additive
(1 drop per
2cm3)
on the rate
of additives
of
: 10% n-propanol
at 26°C)
Relative
rate/
absorbance units
per min.
Additive
(1 drop per
2cm3)
0.44
none
0.00
acetic
Relative
rate/
absorbance units
per min.
0.048
ether
DABCO
(1M; ethanolic)
HCl
0.00
0.00
KOH
(1M; ethanolic)
'
0.11(.
(204)
of
45% BF3 etherate
in
HC1(10M; aqueous)
formation
(1M; ethanolic)
0.61
acid
glacial
(a)
- recorded
From Table
inhibit
or
22:
is
the
Effects
spectrum
that
evident
of
rate
the
accelerates
by base,
inhibited
Fig.
39 it
retard
acid
acetic
280C
at
which
small
reaction
the
whereas
The reaction
reaction.
the
supports
amounts
earlier
of
mineral
relatively
is
suggestion
acid
weak
completely
that
the
base
the
absorption
uv/visible
on
and
of acid
10%
toluene
(90%
n-propancl)
:
acid
of croconic
a
ýO
A
aaý
ý-ý as
1 :ý ýl
_-
9a
wavelength
A(a)
(b)
(c)
absorbance
additive
no
drop of
-1
drop of
-1
; I:
0,
/ nm
acid
acetic
glacial
DABCO
1M ethanilic
_. _
-
149
anion
croconic
be seen
can
in
of
Table
from
Fig.
39 causes
be seen
also
is
not
reactive
towards
22,
the
addition
of
DABCO at
of
the
acid
ionisation
complete
from
22 that
Fig.
acetic
hydroxyjulolidine.
level
croconic
has
acid
the
As
indicated
It
acid.
little
can
effect
on
dyes
involves
dissociation.
is
It
known that
the
dialkylarylamines
'ester'
therefore
in
and squaric
dialkyl
the
the
condensation
of
alcohols
give
the
of
that
a possibility
presence
to
acid
intermediate
between
reaction
squarylium
squaric
the
analogous
could
involve
It
acid.
reaction
the
with
was
croconic
croconate
diester
(209;
Et)
acid
(209).
OR
RO
ý0
0ý
0
(209)
To examine
this
synthesised
Thus
croconic
of
ca.
mixture
A very
seem that
of
reaction
the
reaction
toluene
solution
and the
over
the
croconic
alcohol
was then
amount
diester
is
acid
with
co-solvent
was demonstrated
under
heated
small
reflux.
mixed
formation
of
the
on a water
dye
of
at
time
(204)
with
a similar
was
However,
period.
end of
the
(204)
this
no
period.
80°C for
at
was detected.
Thus
in
intermediate
an important
not
for
dye
bath
out.
:
as used
was then
a 30 minute
be detected
850nm could
a 90% toluene
in
was
carried
same concentration
8-hydroxyjulolidine
reaction
20 minutes.
dry
the
R=
8-hydroxyjulolidine
was dissolved
This
reactions.
at
absorption
That
at
croconate
with
spectroscopically
monitored
would
ester
mixture
acid
solution
reaction
diethyl
10% n-propanol
This
its
and
the
diethyl
possibility
it
the
8-hydroxyjulolidine.
is
not
by heating
A significant
strictly
the
two
essential
components
amount
of
(204)
for
in
the
distilled,
was detected
150
spectroscopically.
preparative
value,
in
acid
namely
In
as a specific
diluted
is
acetic
glacial
but
acid,
is
the
by traces
the
reaction,
croconic
presence
of
acid.
an
solvent
such
a weak acid
of
by strong
inhibited
croconic
and
a non-polar
with
catalysed
in
for
acid
in
more rapidly
of
roles
solvent
croconic
extensively
The reaction
two
little
slow and of
solubility
may play
between
proceeds
solvent,
low
and as a good
reaction
8-hydroxyjulolidine
was very
the
of
alcohol
reactant
the
summary,
toluene.
the
Thus
reaction
because
partly
toluene.
alcohol
the
However,
such
bases
acids,
as
as
and polar
solvents.
The evidence
dissociation
the
in
croconic
of
its
the
Scheme 28],
acid
into
and thus
but
uncertain,
diester.
croconate
[e. g.
ketal
any factor
form.
undissociated
is
that
reaction
condensation
reaction
of
suggests
in
(210)
but
there
the
reaction
not
the
of
are
course
of
the
in
solvent
are
[e. g.
half-ester
acid
croconic
the
formation
intermediate
alternatives
other
inhibit
will
involves
alcohol
involve
and the
increased
and di-anion
mono-
Two possible
Scheme 28]
causes
its
The role
does
that
the
hemi-
(211)
in
tautomeric
possible
structures.
0
1
o
RÖ
OH
OR
HO
OH
(211)
(210)
Scheme 28
The kinetic
(210)
or
studies
in
the
apparent.
(211).
indicate
early
suggest
results
Thus
there
that
stages
the
of
the
the
induction
is
intermediacy
period
a build
reaction
until
of
observed
up of
a species
in
the
of
as
reaction
intermediate
a colourless
formation
such
the
dye becomes
151
2.3.3
Conclusions
: The Oxocarbon
The spectroscopic
use
of
suitably
the
shift
the
only
moderate
Both
nucleophilic
the
in
them
diode
employing
absorption
(>80%)
the
have
34 shows
effect
that
near-
intense
narrow
data
optical
dyes
dyes.
these
dye
recording
stability
bands
systems
virtually
strong
feature
for
some
systems.
dyes
is
the
their
generally
poor
more bathochromic
the
for
some
However,
the
could
and photostability
CHLORO-
FROM ELECTRONEGATIVE
DERIVED
dye,
screens.
ultraviolet
DYES
being
giving
be adequate,
would
by using
further
of
a desirable
and light.
heat
to
is
being
trend
property
concentrations
coding
of
BATHOCHROMIC
HIGHLY
to
croconium
rare
This
security
general
the
be enhanced
Table
dyes
in
the
[at
800nm].
disadvantage
unstable
spectrum.
needed
to
possible
and croconium
the
of
use
have
also
at
e. g.
applications
2.4
for
human eye
the
the
case
is
the
with
squarylium
are
and croconium
dyes
to
stability,
the
suitable
colourless
The main
the
of
it
residues
that
lasers.
The infrared
applications,
of
arylamines
squarylium
makes
more
region
absorption
donor
band
absorption
Absorbers
31 and 34 indicates
Tables
electron
near-infrared
infrared
in
powerful
visible
into
which
data
Dyes as Infrared
COMPOUNDS
In
often
dyes,
donor-acceptor
introduced
suitable
electron
electron
active
rich
donor
dicyanovinyl,
systems.
halo-derivative
the
it
aldehyde
residue.
pyridone,
A different
of
or
method
pyrazalone
approach
to
an electronegative
if
a carbanion,
is
then
compound,
nitroso
This
to
This
group.
methylene
acceptor
electronegative
by converting
is
residue
residue,
to
for
the
acceptor
electron
dyes
e. g.
an
the
provides
invaluable
donor-acceptor
contains
condensed
which
and other
it
is
is
to
2,4-dinitro-
use a
a
152
chlorobenzene.
arylamine,
Scheme
This
or
29,
can then
An example
enamine.
studied
be condensed
in
detail
R
R'
of
with
such
an electron
is
a reaction
rich
in
shown
by Blackburn1°'.
\
NRR'
0
cI
c; LTJ&):
fII+
HC1
cl
ci
Scheme 29
is
This
the
a useful
acceptor
donor
general
is
residue
way of
directly
donor-acceptor
making
to
attached
the
dyes,
aromatic
ring
where
of
the
residue.
For
such
groups
withdrawing
to
reactions
The active
derivative
chloro
(212)
there
must
in
order
to
present
to
susceptible
particularly
work
and the
CI
make the
used
thiophene
electron
chlorine
in
this
work
N02
CI
0
method1',
effectively
of
Dyes and Intermediates
(212)
derivative
but
with
S2
(213)
(212)
143,
NO
CN
H
The pyrroline
pyrroline
(213).
derivative
CN
Synthesis
the
were
CN
2.4.1.
atom
substitution.
nucleophilic
compounds
be strong
the
final
thionyl
was synthesised
chlorination
chloride
instead
stage
of
the
literature
by the
out
was carried
quoted
more
oxalyl
chloride.
derivative
The thiophene
previously
in
this
(213)
department144.
was available
from
work
carried
out
153
The dihydroperimidine
ethylene,
and
this
have
work
intermediates,
and perimidine
1-decyl-2(1H)-methyl-benz[c,
been
The pyrroline
described
appropriate
dihydroperimidine
temperature
to
dyes
give
iodide
used
in
with
the
previously.
chlorine
active
d]indolium
Michler's
(212)
compound
in
and perimidine
(214)
and
(215)
was reacted
ethyl
acetate
respectively.
at
room
The dyes
were
CN
CN
CN
NAH
H3C
(H3C)2HCH2C
N
H
(214)
CN
CN
Et
CN
N
Me -<\
N
(215)
purified
by recrystallisation
The analogous
stirring
and were
Michler's
Michler's
ethylene
ethylene
with
by microanalysis.
characterised
(216)
derivative
pyrroline
(212)
in
was prepared
by
acetate
at
ethyl
Me2N
N
CN
CN
CH
ýH
Met
(216)
The dye was characterised
temperature.
room
The synthesis
of
the
benzindole
derivative
by mass spectrometry.
(217)
was effected
by
154
1-decyl-2(1H)-methyl-benz[c,
stirring
(212)
in
ethanol
d]indoliwn
room temperature.
at
iodide
Ethyl
ýDec
,.
NN
(158)
acetate
with
was not
utilised
CN
CN
CH
N,
H
0
(217)
as the
reaction
Even
medium.
t. l. c.,
scale
due to
solvent
after
for
obtained
by mass spectrometry.
generally
were
described
in
this
for
dyes
derived
from
the
The blue
dye
from
(158)
work.
(218)
was obtained
the
by stirring
was effected
be
not
microanalytical
of
acetic
acid.
This
room temperature
for
2 hours.
in
at
solution
as bronzy/gold
was obtained
COOEt
(212)
reaction
2-amino-3-carboxyethyl-4-phenyl-thiophene
with
this
was therefore
confirmation
the
in
and preparative
could
Unsatisfactory
obtained
dye
The pyrroline
data
Structural
product.
(158)
of
ethanol
microanalytical
obtained
results
solubility
from
recrystallisation
satisfactory
this
low
the
that
crystals
gave
a
Ph
H2N
N
(218)
microanalysis.
satisfactory
involves
formation
group
the
of
Attempts
of
thiophene
were
N, N-diethylaniline
bond,
C-C
a
to
made to
to
give
give
rather
than
a secondary
diazotise
a dye
of
reaction
of
reaction
the
amino
amine.
and couple
formula
the
that
interesting
is
It
(218)
(219),
to
but
the
coupling
155
COOEt
CN
CN
\
Me2N
N=N
\/S,
CN
N,,
ýH
(219)
reaction
A...
630nm,
of
to
relative
Although
(218).
This
products.
chlorothiophene
were
with
Thus
encountered
with
to
those
in
isolation
surprising
appropriate
minimal
reaction
dyes
derived
mixture
2-chloro-3,5-
from
the
pyrroline
of
occurred
by-products,
of
only
satisfactorily,
dyes
(220)
and these
and
were
(221)
could
characterised
readily
by mass spectrometry.
H
N
H 3C
(H3C)2HCH2C
ý, 1ý
N02
s,
N
H
Me 2
\ý-21
(220)
N02
CH
Me2N
(221)
S
N02
at
as shown by
be isolated
N02
the
the
analysis.
the
a
20nm
and purification
nucleophile
of
only
from
as reactions
formation
of
showed
dye.
synthesise
analogous
the
the
product
shift
the
of
of
made to
was somewhat
temperature,
t. l. c.
nature
and purification
were
reaction
a bathochromic
The complex
(213)
problems
The crude
represents
attempts
dinitrothiophene
(212),
which
isolation
precluded
room
inefficient.
was very
156
Both
dyes
with
(213)
were
purified
were
by stirring
synthesised
in
ethyl
acetate
by column
as black,
was obtained
the
appropriate
room temperature
at
chromatography
glass-like
over
crystals
nucleophile
for
silica
2 hours.
(221)
and
60,
gel
The dyes
(220)
and
brown
as golden
needles.
2.4.2.
Light
Absorption
Absorption
(220)
being
solvent
solubility
are
40:
were
the
properties
in
measured
to
used
of
results
Table
spectroscopic
(221)
and
Properties
dyes
summarised
determine
molar
in
40 - 43.
Emmx/
ax/nm
(acetone)
use of
spectroscopic
A
A
dyes
absorption
the
Tables
the
(Toluene)
(214)
and toluene,
acetone
precluded
Visible
absorption
from (212)
Dye
of
-
the
(218),
former
(low
coefficients
dichloromethane).
properties
lmol-1cm-1
(acetone)
of
The
dyes
AA
,. x/nm
(acetone-Tol)
(214)
727
702
25,500
+25
(215)
736
745
86,300
-9
(216)
729
713
28,000
+16
(217)
693
692
44,500
+1
(218)
610
595
15,000
+15
Table
41:
Dye
Visible
spectroscopic
absorption
from 2-chloro-3,5-dinitro-thiophene
snax/nm
(Toluene)
(acetone)
properties
lmol-'
CmjRx/
(acetone)
cm-'
derived
of
dyes
derived
&A,... /run
(acetone-Tol)
(220)
530
515
27,700
+15
(221)
573
550
27,700
+23
157
Comparison
(Tables
respectively
accepting
The data
donating
of
than
wavelengths
generally
Again,
the
the
data
of
in
system
dye
was also
(214).
This
most
longer
is
to
one with
of
confirmed
by the
spectrum
dye
dyes
listed
in
the
This
described
ground
polar
(217)
42).
system.
squarylium
a sufficiently
of
(Table
dyes
the
the
all
that
note
than
all
the
are
wavelengths
for
of
residues
own right.
interesting
found
bathochromic
Visible
- near-infrared
dichloromethane
their
two dyes
solvatochromism.
23:
much longer
the
to
Fig.
at
in
and for
work,
Such thiophene
is
exception
electron
this
for
only
a negative
at
observation
maxima
notable
the pyrroline
of
absorb
it
electron
the powerful
donors
absorbs
40 and 41 and was the
exhibit
and (221)
(213).
(218).
40,
has been
the
the
dye
Table
absorption
with
to
shown
electron
(215)
bathochromicity
thesis,
(220)
used throughout
groups
thiophene
from
the
effect
demonstrates
are
as strong
PPP-MO calculated
(215)
(217)
-
dihydroperimidine
this
40 also
regarded
perimidine
relative
bathochromic
the donor
(214)
dyes
with
to the dinitrothiophene
Table
of
dyes
and (216)
40 and 41) shows the much greater
relative
effect
example
(214)
and thus
ability
(212)
residue
dyes
of
in
Dye
Tables
state
in
1. e
A
1. ý
d
4
: ..
_4 I ')
. _i
! r, A
X10
a(I
P.t_tto 0
No-
wavelength
A-
absorbance
/ nm
158
Near-infrared
(214),
(215),
700nm.
dyes
the
It
broad,
very
23 is
With
low
the
molar
broad
value
of
(212)
published
parameters
previously
calculations
are
42:
Dye
and
the
of
which
is
to
relevant
in
earlier
were
the
cyano
nitrogen
work 136.
listed
summarised
(Calc)
dye
the
dyes
results
Amax/nm
of
short
of
of
the
all
to
coloured
(217),
shown in
dyes
possessed
suggestive
of
This
non-planarity
were
then
the
donor
relatively
reduced
also
accounts
bands.
best
Comparison
of
spectra
strongly
(217)
crowding.
used
for
previously
Table
(215)
Parameters
4.5eV
spectrum
curves
dyes
with
series.
spectra
previously
in
residues
dyes
absorption
PPP-MO method.
those
the
coefficients,
The absorption
were
so making
by steric
caused
the
absorption
of
extinction
planarity
for
exception
just
absorbing
the
this
of
(217)
that
The absorption
typical
> 700nm) was observed
dye
with
be noted
human eye.
Fig.
(216),
and
should
were
(A..
absorption
For
were
in
obtained
atoms,
all
used.
Tables
of PPP-calculated
dyes derived
from
Amax/nm
(Toluene)
other
parts
For
sections.
of
the
the
molecule
acceptor
an electron
with
in
by the
calculated
accordance
atoms,
affinity
with
conventional
The results
of
MO
42 and 43.
and experimental
(212)
/run
/A..
(Tol-Calc)
absorption
Oscillator
(f)(Calc)
(214)
756
702
+54
0.84
(215)
758
745
+13
0.46
(216)
752
713
+39
1.1
(217)
674
692
-18
1.1
(218)
632
595
+37
1.2
strength
159
Table
43:
Comparison
spectra
of
of PPP-calculated
dyes derived
from
A.,,,, /nm
(Calc)
Dye
A
/nm
,,,,,
(Toluene)
and experimental
(213)
/nm
tA...
(Tol-Calc)
absorption
Oscillator
(f)(Calc)
strength
(220)
563
513
+50
0.91
(221)
558
550
+8
0.76
Although
the
reasonable
calculated
This
hindrance
present
assumed
strong
in
twisting
the
of
thiophene
is
overestimated
to
the
calculated
The n-electronic
examined
density
for
changes
the
nitrothiophene
dye,
of
and thus
and so the
value
(A..
state
the
and the
will
in
result
the
A
MO-calculated
max
interactions
steric
A...
observed
be
will
is
value
much
+8nm).
=
x
of
these
(215)
using
chromophores
(221)
and
transitions
of
were
as representative
and the
densities
charge
visible
This
Such peri
(221)
there
so reducing
the
for
residue
ring.
plane,
steric
surprising.
(220)
In
of
was used
not
dye
other
n-electron
dyes
these
are
shown in
24 and 25 respectively.
Figs.
It
can
be seen
a build
shows
carbonyl
from
between
PPP-MO method,
The ground
examples.
(221).
characteristics
by the
is
and
the
in
PPP-method
(220)
out
in
are
degree
greater
agreement
by some 50nm.
less
be markedly
As the
poorer
ring
of
the
values
as good as with
dihydroperimidine
on the
wavelength
closer
the
by dyes
atom
not
due to
dyes.
structures
absorption
will
these
interaction
peri-hydrogen
is
agreement
be largely
exemplified
steric
value
the
will
planar
is
This
and experimental
agreement,
classes.
A...
the
separation
group
from
up of
of
negative
the
pyrroline
nitrogen
perimidine
shows
Fig.
the
powerful
24(a)
that
charge
ring
atoms.
in
on the
the
cyano
loss
a
and
The high
donor-acceptor
state,
ground
(215)
and the
nitrogens
of
electron
degree
of
character
dye
density
charge
of
the
160
Fig.
24:
(a)
Ground
state
for
changes
densities
charge
the
first
and (b)
density
n-electron
band of dye (215)
absorption
-46%
N
_473
N
II
\\\
C+.Zß9
i
;. 294
Et
-. 129 -072
+1.135 N
168
-.
/L\+.
+. 96
,
Me-
+ 003
+242
N -. 4 5
H
0.49
+. 006
043
-.
297
ZN
N\321
: 011
oý
+. 468N
151
+. 037
(a)
- .
N
049
-.
N
t"
Et
_.
-" °27N
+. 066
077
+.01 1
Me
2.!
-. o1,6N
c+.00e
066
c
126
-.
01
C
/+/061
-11
+. 0 41
022
19.4
-.
124
+.
\_N°
/+.
"°
'NH
059
+. 007
°.
3
9)
0
-.
085
016
024
+.
-.
(b)
A
(caic)
758nm
=
(toluene)
745nm
=
rnax
A
mix
Light
chromophore.
results
acceptor
[Fig.
Figures
in
absorption
of
migration
part
25(b)].
25(a)
of
the
This
and
to
electron
(b).
is
Thus
the
mirrored
it
first
from
density
as expected
molecule,
trend
give
with
can be seen
excited
donor
the
for
such
the
dye
from
singlet
atoms
state
to
the
a system
(221),
Fig.
25(a)
as shown by
that
in
161
Fig.
25:
(a)
Ground
state
for
changes
the
densities
charge
and (b)
transition
visible
dye
of
densit
n -electron
(221)
39
-.
0
+, 71
N
0
39
-.
32
X0
115
-.
0-. 41
11
-.
121
N
,
+. 0 57-
S
073
-.
0 32
+. 71
006
+.
+. 069
-. 39
-104
07
-.
07
-.
093
-.
±016
+.023
+.025
+.019
N
+.306
11
-.
N
104
-.
0 19
(a)
+. 014
0
+. 018
0-N
019
+.
071+"033
-.
+. 14
t023
-05
+. 01
±023
+. 024
-033
+. 026
+013
ground
nitro-groups
of
of
molecule.
electron
molecule.
the
donating
electron
the
state
of
is
there
density
a build
ýl
thiophene
dimethylamino
Fig.
25(b)
from
the
residue
groups
(calc)
r
= 550
density
on the
and a loss
in
again
shows
donor
to
the
558
=
ý1
(toluene)
m, .
electron
up of
"045
68
02
4N0
-.
bý
the
Q+
-039
032
- .oß6N-.
N+.038
S
+.133
036
-.
0340+.
-.
+204
+. t5
045
the
the
of
density
Michler's
ethylene
characteristic
acceptor
part
from
the
part
migraticn
of
the
162
2.4.3.
Stability
Properties
The stability
described
properties
in
Section
film
acetate
assessed
summarised
44:
Table
2.1.2.4.
and their
to
relative
in
Tables
the
dyes
were
blue
into
cast
and thermal
stability
(148).
The results
standard
Stability
properties
of
pyrroline
based
Photo stability
(% loss)
(148)
(215)
15
2
(216)
39
1
(217)
75
4
(218)
87
27
Stability
thiophene
of
properties
Photo
based
dyes
Thermal
stability
(% loss)
stability
(% loss)
5
8
(148)
(220)
Total
Decomposition
27
(221)
Total
Decomposition
15
in
the
Tables
the
44 and 45,
were
period
dye,
standard
of
surprisingly
with
dyes
dinitrothiophene
the
are
Thermal stability
(% loss)
11
to
cellulose
dyes
68
45:
methods
properties
(214)
Compared
(215)
the
Thus
by the
5
Standard
during
assessed
44 and 45.
Dye
and
were
8
Table
dyes
dyes
lightfastness
Dye
Standard
the
of
the
test.
high,
the
the
in
lightfastness
exception
Table
45 were
The photoparticularly
of
of
properties
(215)
totally
and thermal
as this
were
very
the
poor,
destroyed
of
stabilities
dye was the
most
163
bathochromic
The thermal
however,
the
of
dyes
in
this
stabilities
and dyes
the
of
(215)
section.
dyes
were
much better,
generally
-
(217)
were
more
stable
and
(216)
with
(220)
and
than
the
standard
dye.
By comparing
is
that
clear
thermal
(214)
the
stabilities
than
promising
result,
as the
analogous
thiophene
2.4.4
has
work
reactions
using
donor-acceptor
however
pyrrolines
active
far
are
acetone
which
photochemical
the
u. v.
chloro
that
are
such
lightfastness
dyes.
This
is
and
a
more bathochromic
dyes
unsuitable
for
than
the
in
most
practical
are
provided,
the
dyes.
to
The dyes
absorption.
them
obtain
intensely
The
some applications.
in
polar
and although
value,
poor
less
solvents
their
thermal
than
their
stabilities
cases.
may show adequate
is
condensation
possible
renders
low
generally
properties
is
near-infrared
which
stability
dyes
containing
is
it
bands
their
good
light
possess
thus
room temperature
compounds
restricts
surprisingly
Thus
by simple
absorption
and they
of
that
proved
broad
solubility
media
dinitrothiophene
better
dyes.
dyes
have
coloured
from
the
both
possess
it
respectively
Conclusions
This
are
dyes
pyrroline
(221)
or
if
all-round
if
stability
photostabilisers
are
protection
included
in
164
3.
Melting
EXPERIMENTAL
Points
These
and are
determined
were
uncorrected.
on an Electrothermal
In
by differential
scanning
Thermal
2,000.
Analyst
some instances
calorimetry,
melting
melting
using
point
points
a Du Pont
were
apparatus
measured
Instruments
Spectra
Infrared
Infrared
spectra
Fourier
spectra
were
were
Transform
recorded
Spectrophotometer.
parameters
dye
in
the
was recorded
Table
'fast
46:
scan'
46.
Table
using
mode,
using
was set
The visible
a Perkin-Elmer
a Unicam
and a slit
Spectrometer
settings
ordinate
mode
and ultraviolet
up according
- near-infrared
The uv/visible
of
for
recording
uv-visible
ABS
scan
480nm/min
response
0.5s
lamp
UV/VIS
cycles/time
1/0.05min
peak
0.02A
recorder
ON
ordinate
min/max
0.000/3.000
min/max
190: 0/900.0
abscissa
spectrum
spectrum
using
0.02mm.
2nm
threshold
the
Lambda 9
slit
speed
to
SP600 Spectrophotometer,
width
used
1720 Series
Lambda 15 UV/Visible
Spectrophotometer.
9 was recorded
Fig.
Visible
on a Perkin-Elmer
UV/Visible/Near-infrared
in
Spectrometer.
The instrument
cited
(208)
on a Perkin-Elmer
recorded
spectra
of
165
Chromatography
Thin
layer
coated
Kieselgel
with
aluminium
E).
chromatography
sheets
sheets
layer
with
aluminium
60H.
60 (70-230
out
(without
fluorescent
with
plastic
sheets
indicator)
or
F254 neutral
sheets
Chromatography
mesh ASTM) or
on either
oxide
chromatography
Kieselgel
using
Kieselgel
60 (Merck)
coated
Preparative
was carried
were
(Merck,
prepared
columns
aluminium
were
type
on glass
prepared
with
(M&B)
oxide
(neutral).
N. M. R.
Spectra
Proton
WH400 n. m. r.
Mass
13C magnetic
and
spectra
Spectrometer.
recorded
on
Elemental
were
of
Cellulose
a
dye
in
bombardment
on a Technicon
out
dye-containing
cellulose
(2.5g)
was added
acetate
a beaker
thoroughly
spectra
were
CHN Autoanalyser.
sheet
Immediately
over
the
a clear
until
a glass
onto
a magnetic
with
wet
with
after
film
to
a mixture
glass.
a watch
with
a t. l. c.
casting
for
stirrer
solution
of
the
calculated
The mixture
at
least
spreader
its
adjusted
sized
surface,
1j
amount
was
hours
The film
was obtained.
a similarly
a few mm from
film
acetate
9: 1) containing
(25cm3
covered
stirred
temperature
5mm.
on a VG 12-253
recorded
Spectrometer.
dichloromethane/methanol
placed
using
Procedures
Preparation
of
recorded
(C, H, N)
carried
Experimental
were
The fast-atom
a VG ZAB-E
Analysis
These
cast
were
instrument.
resolution
Quadrupole
room
spectra
Spectra
The low
of
resonance
to
glass
by using
at
was
a thickness
sheet
was
166
microscope
slides
by
caused
After
too
rapid
drying
in
off
the
was peeled
three
days.
slide
frame.
films
photochemical
from
decanted
Synthesis
and then
10 minutes
acetate
to
with
(10ml)
anhydride
dissolved
7.5.
in
At
this
pH pale
(120a)
2-methylperimidine
off
and washed
215-216°C).
with
water,
2.1.2.4)
ligroin
solution
to
room
as salmon
off
pink
(5m1)
at
25 minutes,
These
and aqueous
crystals
the
rapidly
(1.36g
was
solution
were
filtered
from
of
deposited
: 59.3%)
These
crystals.
ammonia
yellow
the
until
and recrystallised
yellow
added
to
were
give
free
and these
m. p.
for
2-methylperimidine
the
crystals.
acetic
room temperature
5 minutes
whereupon
pale
give
to
was added
over
anhydride
acetic
water
cold
and
refluxing
cooling
(2g)
for
as yellow
to
After
raised,
refluxing
a little
directly
Section
in
was stirred
temperature
deposited
was
salt
washed
acetic
of
cool
or
thermal
supernatant
1,8-DAN
room temperature
to
a
(1,8-DAN)(121)
was filtered
solution
After
occurred.
refluxing
the
in
mounted
(120a)
recrystallised
and the
in
least
at
61.5-64°C).
(lit'°5
2-methylperimidine
(20cm3)
the
of
was heated
residue.
heat
to
summarised
and the
1,8-DAN
deposited
ground
anhydride
10 minutes,
59-61°C,
of
Finely
are
for
then
film
the
dye assessed
(Details
(97.5%)
undissolved
the
m. p.
needles,
off,
for
the
temperature,
allowed
1,8-DAN
12 hours
were
the
of
1.8-diaminonaphthalene
commercial
100-120°C)
(b. p.
which
be subjected
then
spectroscopy.
of
for
a vacuum dessicator
pieces
conditions
'clouding'
from
solvent.
and degradation
exposure
Recrystallisation
in
into
could
treatment
film
room temperature
at
was cut
absorption
the
and kept
glass
Such
by visible
Excess
dark
the
the
prevent
of
evaporation
The film
photochemical
to
as spacers,
were
213-215°C,
filtered
(lit'46,
a pH
167
1-Ethyl-2-methylperimidine
(120b)
Ethyl-p-toluene
and heated
were mixed
temperature
for
(o. g.
solution
heated,
with
up to
a further
was dissolved
solid
(2.0g)
sulphonate
160°C over
0.880)(ca.
for
dichloromethane.
The deep
then
separated,
with
This
tar
a green
chromatographed
over
methylperimidine
band
m. p.
General
solvent
108-112°C
removal
the
mixture
then
sodium
gave
pale
was
sulphate
evaporation.
dichloromethane
first
and
1-Ethyl-2-
as a pale
yellow
(0.90g
crystals
yellow
was
extracted
solution
dichloromethane.
column
brown
:
(lit1O9,115°C).
for
Procedures
in
alumina
off
suspension
removed by rotary
in
light
oily
over
was redissolved
at this
aqueous ammonia
dichloromethane
and dried
water
neutral
was eluted
and after
43%),
which
into
(1.8g)
the
cooling,
and the
green
and the dichloromethane
gave
and kept
The resultant
15 minutes,
with
(anhydrous)
After
DMF and poured
50m1).
washed
1 hour
45 minutes.
in hot
stirring,
and 2-methylperimidine
the
2,2-dialkyl-2,2-dihydro-lH-
of
synthesis
perimidines
(A)
Procedure
To a mixture
1,8-DAN
of
(300m1)
was added
the
mixture
heated
60°C
over
are
for
1 hour.
hydroxide
and sulphuric
After
solution
gel
summarised
60.
in
Dyes made by this
Table
47.
acid
(0.1mol)
ketone
The dihydroperimidines
off.
silica
appropriate
sodium
with
neutralised
filtered
at
(10g)
were
cooling,
and the
purified
procedure,
96%) in
(9g,
and the
dropwise
the
white
water
solution
was
precipitate
by chromatography
and their
properties
169
from
n-propanol.
data
are
Dyes made by this
Synthesis
the
45m1)
light
brown
Purification
60/CH2C12),
(16.2g,
heated
was filtered
was carried
out
147-150°,
m. p.
C, 70.87;
requires
The dihydroperimidine
sulphonic
azeotropic
Removal
removal
dissolved
in
(125)
give
(found
5.9;
the
of
and washed
After
(124)
giving
N, 11.02%).
cooling
ethanol.
with
(silica
chromatography
H, 5.51;
(1.25g,
using
water
under
yellow
H,
4 hours.
C, 70.6;
in
heated
dichloromethane
75.75;
for
malonate
as white
H, 5.50;
gel
crystals,
10.85%.
N,
(125)
were
solvent
as pale
: C,
N;
of
and diethyl
(found:
(123g),
(0.07g)
acid
off
eluent
dihydroperimidine
of
150°C
by column
the
of
0.066mo1)
at
solid
97%),
Synthesis
(10.35g,
together
evaporation
C15H14N202
(124)
1,8-DAN
were
characterisation
47.
Table
dihydroperimidine
of
Recrystallised
(42g,
in
summarised
and their
method
4mmol)
toluene
gave
trap
a tarry
(0.5g,
leaflets,
6.0;
N,
16 hours.
for
This
solid.
silica
over
and chromatographed
was
gel
60 to
137 - 140°C,
53%) m. p.
C, 75.63;
C, 5H, 4N20 requires
11.30%.
of
conditions
with
a Dean-Stark
vacuum
and p-toluene
11.76%).
Generalised
procedure
4-nitroaniline
to
A mixture
addition
of
4-Nitroaniline
concentrated
of
ice
for
the
nitrite
(Solution
(1.38g,
hydrochloric
of
and coupling
dihydroperimidines.
and
perimidines
sodium
diazotisation
A).
(0.7g,
The ice
0.01mol)
acid
0.01mol)
slurry
was dissolved
(5m1)
and glacial
was cooled
was used
in
to
immediately.
a mixture
acetic
0°C by
acid
of
(10ml)
H,
170
heating.
with
(Solution
The hot,
and the
A)
a clear
solution
The perimidine
This
B was added
dropwise.
resultant
suspension
was then
possible,
and the
first
give
the
was then
48 and
Tables
Table
48:
Dye
(130f)
(130g)
(130h)
(130i)
for
prepared
in
to
to
in
<5°C and
10 minutes
as near
the
dryness
silica
over
this
as
The dried
dichloromethane.
azo dye
ortho
gave
in
dissolved
for
chromatographed
the
dyes
into
was dissolved
cooled
evaporated
This
gel
60 to
isomers.
way are
in
summarised
49.
data for
monoazo
Characterisation
dihydroperimidine
Appearance
of
and melting
the ortho
dyes
coupled
deep red
violet
74-75°C
and
calc:
found:
C24H27N502
C, 69.06; H, 6.48; N, 16.79%
C, 68.95; H, 6.50; N, 16.80%
'/e
deep red/green
202-204°C
green
metallic
199-2010C
perimidine
Characterisation
data
crystals
point
green
metallic
191-193°C
275ýC
(134b)
column
and then
data
Characterisation
rotary
slurry
B).
(5g)
stirring
dye extracted
crude
para
After
ice
15 minutes.
(10mmol)
was then
the
onto
(Solution
salt
solution
solution
CH2C12 solution
0°C for
(60cm3) and sodium acetate
added.
water(20m1)
diazonium
at
dihydroperimidine
or
dimethylformamide
was poured
stirred
mixture
the
of
solution
clear
calc:
found:
462
=
C30H25N502
C, 71.5 ; H, 4,97; N, 13.91%
C, 71.35; H, 4.78; N, 13.75%
C30H21N503
14.43%
4.74;
N,
74.2
H,
C,
;
calc:
found : C, 74.05; H, 4.45; N, 14.55%
"/e
360
=
(= M+1)
171
Table
49:
Characterisation
dihydroperimidine
Dye
data
the para
dyes
monoazo
Appearance
of
and melting
(131f)
for
crystals
point
coupled
perimidine
and
Characterisation
data
metallic
green
182-185°C
C24H27N5O2
C, 69.06; H, 6.48; N, 16.79%
calc:
found : C, 69.10; H, 6.35; N, 16.52%
(131g)
dull
(131h)
green
194°C
dull
purple
155-157°C
(131i)
pale yellow
242-245°C
(135b)
Michler's
of
to
separately
dry
calc:
found:
C21H17N503
C, 65.12; H, 4.4 ; N, 18.1 %
C, 64.9 ; H, 4.65; N, 18.55%
calc:
found:
C21H N504
C, 62.5 ; H, 4.2 ; N, 17.36%
C, 62.45; H, 4.15; N, 17.40%
ceased,
leaving
prepared
solution
toluene)
in
in
amount
orange
of
of
toluene
the
a steady
by heating.
precipitation,
suspension
was stirred
mixture
To this
(9g)
which
aliquot
of
for
was stirred
(recrystallised
[The
to
for
a previously
from
twice
Michler's
Ketone
room temperature
was ignored].
vigorously
added
was stirred
was added
stream.
Cooling
were
and self-refluxing
effervescence
Ketone
in
a further
The reaction
suspension.
Michler's
(250m1)
The suspension
had started
until
(4.2g)
turnings
(20m1).
was added.
a grey
toluene
dissolved
was
magnesium
ether
20 - 25 minutes
a further
= 359
(149)
effervescence
(80m1)
ether
and dry
diethyl
and when vigorous
deep
C, 74.2 ; H, 4.74; N, 14.43%
C, 73.95; H, 4.90; N, 14.10%
`"/e
Ethylene
(25m1)
Iodomethane
a small
calc:
found:
metallic
green
100-102°C
Synthesis
had
C30H21N503
dull
green
273-275°C
(133)
C3oH23N502
C, 71.5 ; H, 4,97; N, 13.91%
C, 71.45; H, 5.00; N, 13.79%
calc:
found:
dull
green
152-154°C
(132)
diethyl
m/e = 462
gave
The resulting
22 hours
with
the
172
exclusion
light.
of
effervescence)
of
and the
glacial
(150m1)
acetic
31 hours
after
sulphate,
residue
(lit128,121
Preparation
-
of
benz[c,
to
To this
Finely
and the
After
cooling
under
stirred
vacuum
vacuum,
at
and the
eventually
172 -
Preparation
Benz[c,
176°C
of
maintaining
at
stirred
d]indol-2(1H)-one
and added
Dissolution
tar
resulting
1 hour.
tar
was mixed
steam-distilled
yellow
as pale
180 -
160°C.
at
1 hour.
at
150 -
15 minutes.
for
was distilled
with
was then
for
anhydrous
added
as possible
The water
in
a further
was then
temperature
this
prepared
temperature
160°C for
100°C as much solvent
1-decyl-benz[c,
327m1).
42.4m1)
the
chloride
(lit12',
120°C
as
was powdered
0.21mol,
0.6mol)
(156)
The
116 -
a previously
(35g,
resultant
afforded
1 hour
at
for
anhydrous
(149)
(426g,
(36g,
83m1),
and the
90°C
0.54mo1)
stirred
mixture
to
m. p.
was then
sodium
ground
160°C
m. p.
mixture
over
(156)
over
1-naphthylisocyanate
The reaction
28%),
(72g,
was added
o-dichlorobenzene
by
give
to
for
160°C.
to
(108g,
dried
ethanol
water
was stirred
under vacuum.
o-dichlorobenzene
anhydrous
solution
of
solution
(2.49g,
chloride
by heating
was effected
from
in
was removed
to dryness
d]indol-2(1H)-one
aluminium
immediately
hydroxide
A solution
(30g)
suspension
was separated,
twice
needles,
122°C).
Anhydrous
and
layer
and evaporated
lustrous
green
(vigorous
5 minutes.
and ammonium chloride
magnesium
was recrystallised
green
off
the
The organic
sodium
pale
(15m1)
added dropwise
for
stirred
added and the pale
which
filtration.
suspension
acid
was then
(200m1) was then
Water
removed
8 hours
(15g,
platelets,
(400m1)
water
under
which
42%),
181°C).
d]indol-2(1H)-one
(1.69g,
0.01mol)
(157)
was dissolved
in
hot
173
o-dichlorobenzene
was added.
(60ml)
To this
bromide
n-decyl
for
turned
a deeper
filtered
through
2 hours
organic
the
all
yellow
71%),
started
dry
this
-5
0°C
to
-
ensuring
(158)
General
(149)
at
the
procedure
or
(158)
4-nitrobenzenediazonium
to
remove
solid,
iodide
(158)
for
diethyl
dry
minus
the
(lmmol)
to
remained
at
solution
of
(25m1).
water
(2.27g,
96%),
requires
of
dissolved
was
under
(0.24g,
ref lux
of
added
dropwise,
The deep
and then
filtered
m/e = 308;
[found,
m/e = 308].
azo dyes
in
finely
The
heated
20°C.
5 minutes
I-),
One tenth
dropwise
(11ml)
for
preparation
chloride
added
then
below
mixture
ceased.
<10°C and a solution
in
(1.4g)
diethyl
The reaction
ether
15 minutes
dry
of
When effervescence
stirred
and well
was stirred
product
a mixture
was then
was cooled
powder,
to
and self-refluxing
acid
as an orange
(for
and
and the
yellow
d]indolium
was added.
0°C for
temperature
the
suspension
orange/red
in
7mmol)
(2g,
hydrochloric
that
distilled
as a pale
(60m1)
prepared
The mixture
concentrated
layers,
(2.4g).
by volume
a previously
1 hour.
two distinct
turnings
ether
was stirred
suspension
C22H30N
magnesium
solution
(157)
benzindole
was cooled
(157)
was added
effervescence
Grignard
powdered
O. lmol)
diethyl
until
of
under
The solution
and steam
gave
heated
by
43 - 45°C.
and dry
was stirred
give
was isolated
This
(14.2g,
more
to
powder
50m1)
followed
was then
precipitated
1-decyl-2(1H)-methyl-benz[c,
of
(20m1)
the
and re-dissolved.
layer
(0.05g)
The mixture
time
which
cellulose
m. p.
Iodomethane
give
during
yellow
Preparation
for
0.0125mo1).
(45%w/v,
solution
18-crown-6
was added
o-dichlorobenzene.
(2.19g,
ether
solution
(2.75g,
reflux
upper
and sodium hydroxide
ethanol
1mmol)
(162)
(10ml)
added.
and
(163)
and
The solution
to
174
was stirred
filtered
at
off
(162):
Dye
metallic
415,
and washed with
green
(163):
green
Preparation
(125m1)
then
with
temperature
brown
then
90%),
m. p.
Formylation
dropwise
filtered
free
acid
was obtained
as white
necked
(400m1)
was
60°C.
at
acid
with,
three
and the
initially,
needles,
The
pale
hot,
(44g,
3-cyano-6-hydroxy-4-methyl-2-pyridone
thickened
temperature
hydrochloric
with
The product
temperature
to
cooling
litre
Water
solid.
the
and washed
was cooled
hydroxy-4-methyl-2-pyridonekwas
added
the
heated
mixture
After
a1
ethyl
with
>300°c.
of
to
to
of
a mixture
and stirring
mixed
6 hours.
120°C for
dissolve
to
and the
was transferred
acidified
off
was then
(65m1)
maintaining
whilst
10.2m1,0.11mol)
mixture
at
60°C to
Dimethylformamide
(16.9g,
m/e =
m/e = 456;
0.264mo1),
(29.9g,
and water
stirring
to
water.
cold
(found
stirring
with
The solution
mixture
was strongly
solid
as
as metallic
(found,
75 - 78°C,
cyanoacetate
the
and heated
solution
216 - 218°C,
chromatography
76m1) was added
0.308mo1)
(40g,
added
and was obtained
m. p.
layer
m. p.
12 hours.
for
an autoclave
flask
solid
456).
=
(33%,
and ethyl
was continued
room
m/e
ammonia
acetoacetate
resulting
3-cyano-6-hydroxy-4-methyl-2-pyridone
of
Aqueous
ethanol
31%),
by thick
6%),
requires
and the
m/e = 415).
was isolated
C2BH32N402
in
from
requires
(0.2g,
1 hour
water.
(0.38g,
needles,
needles,
water
for
was recrystallised
C24H25N502
Dye
temperature
room
maintain
below
during
stirring.
1 0°C for
added
to
0°C and phosphorous
stirring
with
0 7-63 Q.I Im',i)
; then
added
addition
3-Cyano-6-
<10°C.
the
as
and
portionwise
(50m1)
dimethylformamide
so more
The stiff
2 hours,
at
oxychloride
white
and the
paste
was stirred
temperature
then
at
was
a
allowed
175
to
to
rise
60°C
and maintained
into
was poured
to
20°C overnight.
ca.
15°C with
this
at
temperature
(800ml)
water
ice
The mixture
60°C.
at
and the
addition,
and dried
water
2 hours,
after
yellow
were
in
heated
The suspension
dull
formyl-6-hydroxy-4-methyl-2-pyridone
ice-cold
for
was then
55 -
crystals
of
off,
(14.2g,
85%),
it
which
was then
filtered
a dessicator,
to
cooled
3-cyano-5-
washed
with
212 -
m. p.
214°C.
Nitrosation
3-cyano-6-hydroxy-4-methyl-2-pyridone
of
3-Cyano-6-hydroxy-4-methyl-2-pyridone
(1.9g,
nitrite
(40% w/v;
2.5m1)
solution
of
yellow
pyridone
194 -
and stirred
was added
off,
hydroxide
a clear
a previously
hydrochloric
for
sodium
sodium
until
to
slowly
was continued
of
0.025mo1),
and aqueous
and concentrated
Stirring
filtered
together
mixed
This
crystals
(37.5ml)
water
(100ml)
water
0°C.
to
cooled
m. p.
were
was obtained.
mixture
pale
0.025mo1),
(3.75g,
1 hour
acid
at
0-
prepared
(10ml),
5°C and the
3-cyano-6-hydroxy-4-methyl-5-nitroso-2washed
with
dried,
and then
water
(3.96g,
89%),
195°C.
Condensation
(149)
of
and
(158)
with
3-cyano-5-formyl-6-
various
hydroxy-4-methyl-2-pyridones
(149)
Derivative
and
added.
After
to
cooling
give
the
crude
summarised
in
(0.5mmol)
The dyes
dye.
column
Table
50.
was dissolved
in
(0.5mmol)
heated
temperature
room
or
recrystallisation
are
was then
The mixture
to
(158)
formyl-pyridone
the
of
a solution
or
under
the
were
ref lux
resultant
purified
chromatography,
in
ethanol
for
solid
either
ethanol
(5m1)
(5m1),
was
30 minutes.
was filtered
off
by
and characterisation
data
176
Table
50:
Structure
(178a)('a)
Characterisation
data
5-nitroso-2-pyridones
Yield
%
52
for
Appearance
of
and melting
metallic
dyes derived
(178b)(°'
(180b)(°'
(178c)(1)
47
green
metallic
green
251-253°C
40
blue powder
>350°C
pale
55
dull
green
41
dull
"
green powder
255-258°C
72
dull
(181a)`°'
84
deep green needles
198-200°C
(179b)`°'
14
46
found:
C, 73.05;
calc:
found:
C25H25N502
C, 70.25; H, 5.85; N, 16.39%
C, 70.05; H, 5.80; N, 16.45%
calc:
found:
C, 74.00; H, 6.6
C, 74.3 ; H, 6.8
(179c)`')
blue
C31H37N502
(a)
(b)
(c)
(d)
-
83
dull
C, 72.7
; H, 7.24;
found:
C, 73.0
; H, 7.20; N, 13.51%
C30H3BN6O2
calc:
found:
C, 70.3 ; H, 7.03; N, 16.4
C, 70.05; H, 6.95; N, 16.3
m/e = 468
(= M+1)
m/e = 468
m/e = 495
m/e = 496
needles
m/e = 552
powder
m/e = 553
green needles
>300°C
from
ethanol
recrystallised
by
column chromatography
purified
from
acetate
ethyl
recrystallised
by
column chromatography
purified
N, 13.69%
calc:
>300°C
(181c)`11'
%
%
; H, 6.4 ; N, 15.40%
; H, 6.55; N, 15.65%
calc: C, 71.2
found: C, 70.9
191-194°C
51
; N, 12.3
; N, 12.3
C27H29N502
blue/green
dull
210-215°C
deep green
H, 6.15; N, 12.70%
C2eH3oN402
blue powder
220-221°C
(179a)(-)
(181b)(°'
C26H26N402
needles
217-219°C
(180c)(1)
and
calc: C, 73.20; H, 6.10; N, 13.10%
green/blue
powder
>300°C
68
5-formyl-
Characterisation
data
crystals
point
261-263°C
(180a)(°'
from
gel
over
silica
over
aluminium
60
oxide
%
%
177
Condensation
(149)
of
and
(158)
with
various
as for
the
3-cyano-6-hydroxy-4-
methyl-5-nitroso-2-pyridones
The
same procedure
be carried
reaction
could
1 hour.
The results
General
(2mmol)
acid
refluxed,
with
for
(20m1)
by using
dye
chromatography
This
layer
60.
this
method
50.
dyes
squarylium
arylamine
off,
are
60.
in
summarised
and toluene
was cooled
toluene
with
were
was removed
The mixture
washed
gel
silica
(40m1)
formed
trap.
(4mmol)
enamine
n-butanol
water
a Dean-Stark
filtered
or
of
and the
was similar
for
was substituted
dyes
toluene
for
Yields,
and
by
and purified
and
m. p.,
51.
Table
B
Procedure
remove
of
a mixture
over
data
characterisation
for
in
20minutes-32hours
precipitated
(40m1)
room temperature
at
in Table
synthesis
and the
stirring
azeotropically
column
the
and the
A
Squaric
the
for
formyl-pyridones
by stirring
out
are summarised
procedures
Procedure
was used
that
the
did
not
could
Yields,
procedure
over
anhydrous
be directly
then
m. p.,
are
out
then
it
drying
This
sodium
sulphate.
column
chromatographed
in
Table
date
51.
of
n-propanol
had the
on cooling
water,
with
and characterisation
summarised
This
n-butanol.
crystallise
that
A except
Procedure
the
by washing
alcohol
layer
to
dyes
that
advantage
to
was possible
the
dried
over
separated
toluene
silica
gel
made according
to
178
Table
51:
Yields
Structure
Yield
%
(189a)'
data
and characterisation
Appearance
of
and melting
80
dull
green
for
squarylium
crystals
point
Characterisation
data
needles
m/e = 531 (= M+1)
needles
m/e = 558
blue
'/e
>300°C
(189b)*'
70
dark
green
158-159°C
(189c)
80
"
lustrous
614
=
119-120°C
(189d)*"r
33
(189e)
dull
green
176-180°C
41
(189f)"`ß
(192)'*
metallic
C, 83.2 ; H, 5.10; N, 7.5
C, 82.95; H, 5.35; N, 7.15
calc:
found:
green
>300°C
5
(194)
80
***
Procedure
Procedure
-
Synthesis
a.
of
Preparation
dull
C, 71.79; H, 6.55; N, 8.0
C, 71.8 ; H, 6.80; N, 7.65
calc:
found:
needles
C, 77.10;
calc:
cooled
over
stirring,
below
minutes.
10°C.
; H, 5.3
; N, 11.1
m/e = 610
m/e = 693
(= M+1)
acid
(198)
tetramethoxy-p-benzoquinone
Sodium hydroxide
and
H, 5.22; N, 11.25%
(A)
(B)
of
to
C, 76.9
green needles
121-122°C
croconic
below
10°C.
20 minutes,
The suspension
The reaction
0.4mol)
(16.25g,
Chloranil
ensuring
was then
mixture
in methanol"(600ml)
dissolved
was
0.1mol)
(25g,
that
the
heated
filtered
was
%
%
C32H26N402
very deep green
82-84°C
anhydrous
%
%
C42H46N406
found:
(193)x"
%
%
C52H39N402
pale green
-86-88°C
85
C52H34N404
C, 80.21; H, 4.37; N, 7.20
C, 80.30; H, 4.45; N, 6.95
calc:
found:
dull
blue
>300°C
81
dyes
was added,
temperature
under
off
reflux
and,
with
remained
for
50
on cooling,
%
179
orange
needles
138°C
b.
(198)
of
(lit""
of
(198)
43mmol)
(10g,
acetic
reaction
(100ml)
acid
was then
Preparation
hot
hydroxide
sodium
of
tetrahydroxy-p-benzoquinone
manganese
dioxide
45 minutes.
of
filtration
Barium
(60°C)
resultant
76%),
washed
with
gave
(200)
to
water
in
platelets
the
the
remove
To
hydrochloric
A hot
water
of
for
(2 x 40m1).
concentrated
(5g)
was
refluxed
solution.
yellow
was heated
mixture
hot
hot
was added
yellow
This
filtered
(120m1)
water
solution
was then
(15m1)
barium
to
85 - 90°C and cooled
to
as lustrous
yellow
platelets
70%).
of
Preparation
hot
bright
The suspension
salt.
temperature,
(2.49g,
gave
and active
and then
minutes
trihydrate
chloride
give
(5.5g).
a bright
giving
barium
to
mixture
in
0.012mol)
was then
and filtrate
dropwise,
dropwise,
room
This
(5.64g,
0.12mol)
(4.8g,
five
was then
which
washings
(21m1)
croconate
(2M).
(200)
(2.1g,
for
temperature
dioxide
90°C)
The
vacuum and the
under
platelets,
Chemicals),
The reaction
combined
added
d
(Aldrich
room
at
(ca.
of
(48%, 100ml).
acid
hydrate
croconate
was added
acid
red
a mixture
acid
hydrochloric
as deep
in
dryness
to
evaporated
barium
of
To a solution
manganese
1 hour
(1it'40>300°C).
m. p. >300°C,
the
135 -
m. p.
(199)
and hydrobromic
from
recrystallised
stirred
for
was refluxed
tetrahydroxy-p-benzoquinone
c.
42%),
tetrahydroxy-p-benzoquinone
mixture
residue
(9.59g,
135°C).
Preparation
glacial
deposited,
were
croconate
mixture
pale
anhydrous
hydrate
of
yellow
water
croconic
(2.75g,
(10ml)
suspension
acid
9mmol)
was added
and sulphuric
was stirred
at
acid
this
to
portionwise
(98%;
lml).
temperature
a
The
for
180
40 minutes
filtered
and
The precipitate
filtrate
and
residual
tarry
solid
croconic
acid
as pale
were
refluxed,
toluene
with
(20m1)
washed
alcohol
dried
over
over
52:
silica
gel
Characterisation
Structure
Yield
%
(203)
83
with
sulphate
are
for
data
green
not
the
(40m1)
n-propanol
the
formed
Table
and
was removed
was cooled
was filtered
and
out,
the
toluene
separated
directly
m. p.,
(4mmol)
enamine
crystallise
Yields,
in
or
product
layer
column
and
52.
croconium
dyes
Characterisation
data
crystals
point
C25H28N205
metallic
219-221°C
dyes
water
and then
60.
anhydrous
The mixture
water,
summarised
Appearance
of
and melting
olive
the
dye did
sodium
data
characterisation
Table
by washing
anhydrous
chromatographed
out,
Where the
was removed
trap.
The
85%).
of
and the
combined
vacuum.
giving
croconium
a mixture
sulphate.
and the
under
3-hydroxyarylamine
a Dean-Stark
dye precipitated
toluene.
with
in
dryness
acetone,
of
barium
20m1)
(1.09g,
synthesis
11minutes-1hour
by using
when the
with
and the
(ca.
to
crystals
stirring,
for
azeotropically
and,
the
insoluble
water
evaporated
yellow
(2mmol)
acid
hot
was slurried
for
the
remove
with
were
procedure
Croconic
to
was washed
washings
General
hot
calc:
H, 6.42; N, 6.42
C, 68.80;
%
found: C, 68.70; H, 6.65; N, 6.15 %
(204)
(205)
(207)
(208)
brown
dull
245-247°C
89
C29H28N205
calc:
found:
C, 71.9
C, 71.6
; H, 5.8 ; N, 5.80
5.50
5.75;
N,
H,
;
(= M+1)
green/yellow
244-245°C
m/e =465
4
brown
dull
168-170°C
m/e = 655
(= M+1)
26
brown
dull
69-72°C
m/e = 721
(= M+1)
75
dull
%
%
181
Procedures
acid
in
used
Croconic
of
alcoholic
after
the
solution
manner
An aliquot
the
This
the
intervals
over
in
a sonic
bath
solvent
45m1 n-propanol:
dark
until
mixed
with
dark
time
1.76
5m1 toluene).
after
the
mixing
time
inside
the
experiment.
solvents
the
of
volumes
solution
in
the
flask
minimum
by placing
on
was made up to
solution
10% toluene
This
a known
a 1mm quartz
temperature
the
a
was mixed
30 second
at
a 50 ml graduated
which
at
to
was dissolved
x 10-4mol)
required
acid
One minute
mixed
in
amine.
croconic
was transferred
the
30
a graduated
solution
throughout
after
the
the
of
of
for
was prepared
was recorded
90% n-propanol:
(e. g.
x 10-°mo1)
period,
in
n-propanol
bath
required.
solution
involving
of
until
the
n-propanol
and the
required
was then
stored
in
the
required.
manner
An aliquot
formation
30 minutes,
for
the
solution
recorded
(25mg,
8-hydroxyjulolidine
The corresponding
similar
croconic
in
50m1 in
8-hydroxyjulolidine
solutions
by additions
mark
second
dye
being
of
3.52
mixture
a 30 minute
acid
possible
in
spectrophotometer.
of
of
volume
the
of
the
rate
Preparation
was made up to
alcohol
reaction
spectrophotometer
Croconic
the
of
same amount
solutions
alcohol
(0.0665g,
using
and placed
the
of
on a sonic
8-hydroxyjulolidine
(5ml)
temperature.
b.
reaction
was dissolved
by placing
was stored
The corresponding
cell
the
of
x 10-4mol)
alcohol
which
This
with
1.76
distilled,
minutes,
similar
studies
solutions
(25mg,
acid
appropriate,
flask.
kinetic
8-hydroxyjulolidine
with
Preparation
a.
the
(0.0665g,
using
(5m1)
5m1 of
of
the
the
3.52
mixed
corresponding
was prepared
solution
x 10-4mol)
solvent
of
solution
8-hydroxyjulolidine
the
amine.
of
croconic
mixed
in
a
acid
solvent
was
182
solution
a known temperature.
at
transferred
to
The rate
for
dye
of
1 hour
formation
(when
acetonitrile)
the
from
Experiments
that
the
quartz
the
spectrophotometer,
bases;
This
hydrochloric
potassium
hydroxide
Synthesis
of
To a stirred
(10ml)
water
the
diethyl
of
(when the
1 minute
had
spectrophotometer
was
one drop
rate
the
of
known
procedure
(1M;
identical
a manner
to
a spectrophotometer
8-hydroxyjulolidine
the
of
cuvette
dye
then
were
formation
for
in
the
glacial
ether;
in
intervals
following
acetic
DABCO (1M;
to
a 1mm
the
30 second
was repeated
(10M;
acid
transferred
recorded
at
ethanolic);
solution
hydrochloric
temperature,
(1M;
etherate
in
solution,
was added
of
in
in
above.
of
for
acids
and
acid;
ethanolic);
and
ethanolic).
croconate
silver
solution
was added a solution
(30m1).
after
or
and bases
acids
acid
acid
trifluoride
Preparation
starting
inside
a 1ml aliquot
at
45% boron
a.
(b)
and
croconic
and the
30 minutes.
30 minutes
prepared
(a)
intervals
experiment.
added
The contents
cell
for
were
mixture
aqueous).
1 minute
either
: 10% n-propanol
was added
this
spectrophotometer.
and 8-hydroxyjulolidine
in
was
dimethylformamide
intervals
toluene)
or
the
acid
To 1ml of
and to
in
was either
time
mixture
croconic
of
described
cuvette,
at
The temperature
involving
The solutions
90% toluene
was recorded
water
mixing.
throughout
recorded
reaction
and placed
co-solvent
was either
elapsed
cell
30 second
or
co-solvent
c.
a 1mm quartz
This
The resulting
croconate
of
croconic
of silver
bright
acid
(1.42g,
nitrate
orange
0.01mol)
(3.4g,
suspension
and water
0.02mol)
and
was stirred
in
183
the
absence
and dried
b.
light
of
in
in
light
4 hours.
dry
yellow
to
any
dichloromethane
column
A further
layer
Diethyl
band
and,
(0.5g,
0.1%),
Kinetic
aspects
of
anhydrous
directly
over
silica
removal,
rate
60,
which
tarry
pale
with
water
sulphate
with
and
acetone
only
as a golden
(204)
of
5.7mmol)
after
as the
as
yellow
yellow
oil,
m/e = 216).
requires
formulation
of
gel
of
the
sodium
was eluted
06
(0.9g,
separation,
was afforded
C9H,?.
absence
and washed
over
(8.1g,
from
diethyl
croconate
8-hydroxyjulolidine
and
Diethyl
croconate
in
treatment
the
to
mark
a 50ml
a sonic
3.52
to
x 10-4mol)
an equal
and
of
diethyl
the
of
the
the
The flask
to
was added
and solution
by
effected
was then
made up
rate
was prepared
solution
croconate
of
diethyl
in
a
(0.0665g,
using
solution
croconate
8-hydroxyjulolidine
The reaction
the
x 10-4mo1)
8-hydroxyjulolidine.
of
volume
temperature.
flask
30 minutes.
8-hydroxyjulolidine
(5m1)
An aliquot
1.7
toluene.
with
manner
graduated
for
bath
The corresponding
similar
(38mg,
monohydrate
in
(5m1),
n-propanol
cell
dichloromethane
monohydrate
the
The resultant
vacuum.
was dried
m/e = 216;
in
12 hours,
After
solvent
(found
a further
acid.
croconate
after
under
and iodoethane
iodoethane
croconic
chromatographed
eluent.
0.025mo1)
of
for
in
off
91%).
was stirred
aliquot
was removed
was filtered
monohydrate
(9g,
continued
residual
(3.24g,
(30m1)
ether
was dissolved
residue
remove
diethyl
ether
dark,
croconate
and stirring
diethyl
the
The precipitate
croconate
of silver
0.052mol)
the
in
diethyl
of
A solution
was added
20 minutes.
a dessicator
Preparation
for
for
dye
mixture
formation
was mixed
solution
solution
to
was transferred
was recorded
at
over
with
known
a 1mm quartz
30 minutes
at
184
30 second
time
internal
the
temperature
duration
(120m1)
inert
atmosphere
added
sodium
120°C
with
stirring.
(0.15m1)
To this
solution
portionwise
heated
in
to
4 hours.
(10ml)
3
oxo
40°C over
evolved
toluene
(100ml)
to
destruction
was added,
5 minutes.
ice(200g)
hydrochloric
product
20%),
mixture
acid
172 -
excess
crude
which
off,
that
the
was
30 minutes,
off
added
to
to
water
was
temperature
and air
an
1400m1 with
concentrated
with
to
being
mixture
that
at
20 minutes.
washed
methanol
was
malononitrile
filtered
diluted
was
for
of
solution
After
was then
with
20°C without
(NB. much heat
product
acidified
to
ensuring
sodium).
product
bath,
reaction
dropwise,
30 - 50°C
and stirred
174°C.
latter
the
and maintained
added
between
filtered
a solution
The resultant
20 minutes
the
cool
of
an
was heated
mixture
by a solution
(50m1),
mixture
(35m1)
an ice-water
to
allowed
added
followed
was then
was then
m. p.
was then
The crude
: water(300m1)
This
and then
of
from
cooling
in
sulphonate,
The reaction
was then
was maintained
due
external
10 minutes.
over
benzene
alkyl
tetrahydrofuran
Methanol
temperature
of
portionwise.
stirring
added
(30.4g,
and with
and xylene
for
1 drop
and
vigorous
1.13mol)
white
experiment.
(10.4g)
(75g,
water.
throughout
was recorded
dimer
To xylene
dried
spectrophotometer
The
mixing.
(212)
Malononitrile
for
the
after
3-chloro-4-cyano-5-dicyanomethylene-2
of
pyrroline
then
1 minute
starting
of
the
of
Preparation
a.
intervals,
The final
and dried,
185
b.
Preparation
the
of
sodium
salt
4-cyano
of
3 dicyanomethylene
3
hydroxy-2-oxo-3-pyrroline
To a solution
(prepared
This
of
sodium
After
warming
solution
third
the
was added
filtered
methanol
for
15 minutes
off,
washed
1 hour.
with
The product
acetic
acid
stirred
for
added
to
30 minutes
at
50°C,
c.
Preparation
rapidly
then
of
of
thionyl
the
clear
20°C over
2 hours
water
The resulting
Stirring
was
crystals
were
dried
(400m1),
off
then
at
50°C
and
suspension
filtered
product
and one
(2 x 50m1)
and then
petrol,
in
yellow
Toluene
yellow
dissolved
filtered
off,
was
and dried
reduced
Synthesis
of
The chloro
to
dyes
(214)
compound
(1mmol)
were
in
0.043mo1)
1 hour.
5°C over
then
at
50°C.
-
(216)
(212)
dissolved
(20g,
(0.2g,
in
(20m1)
acetonitrile
The mixture
dichloromethane,
with
pressure
4-cyano-3-dicyanomethylene-
of
dropwise.
(10ml)
and cooled
washed
salt
sodium
(10g,
chloride
30 minutes
reactant
0.2mol)
3-chloro-4-cyano-5-dicyanomethylene-2-oxo-3-
3-hydroxy-2-oxo-3-pyrroline
under
the
vacuum.
toluene,
yellow
(4.7g,
(21g, 31.3%).
To a solution
for
32°C),
resultant
and the
methanolic
sodium
crystallised.
.
dropwise.
cooling.
and the
a pH 4.5
methanol
15ml)
prepared
ca.
under
in
(212)
pyrroline
added
to
was then
give
(16g,
a maximum of
was removed
gel
oxalate
with
stirring,
the
0.1mol)
made by dissolving
(to
with
(13.2g,
a previously
nitrogen,
gently
whereupon
maintained
for
under
was cooled,
of
to
added
methoxide
(75m1),
methanol
diethyl
was added
was then
solution
dimer
malononitrile
by heating)
solution
in
of
was then
The product
cyclohexane
refluxed
was then
and dried
84.5%)
lmmol)
ethyl
and the
acetate
appropriate
(15m1)
was
and stirred
186
heating
without
washed
are
with
for
in
53:
Table
Table
Yields,
Yield
%
(214)
24
(215)
98
(216)
m. p.,
data
Appearance
of
and melting
for
dyes
data
13
green
metallic
260-261°C
(218)
76
bronzy/gold
248-250°C
-
(218)
C24H20N6O
calc: C, 70.58; H, 4.90; N, 20.58%
found: C, 70.80; H, 5.05; N, 20.55%
calc:
found:
C21H N6O
C, 68.85; H, 3.82; N, 22.95%
C, 69.1 ; H, 3.68; N, 22.87%
C26H22N6O
19.4
5.10;
N,
71.88;
C,
H,
calc:
found: C, 72.0 ; H, 4.8 ; N, 19.8
dull
green
>300°C
(217)ßd'
(214)
Characterisation
data
blue/green
>300°C
74
off,
and characterisation
crystals
point
dull
blue/grey
252-255°C
dull
filtered
were
53.
Characterisation
Structure
dyes
The resulting
and dried.
water
summarised
1 hour.
475
=
-/e
needles
C21H14N503S
calc: C, 60.57;
found: C, 60.25;
filtration
hot
toluene
after
- recrystallised
o-dichlorobenzene
recrystallised
silica
over
by
chromatography
column
- purified
filtration
hot
from
after
ethanol
recrystallised
-
H, 3.3
H, 3.0
; N, 16.82%
; N, 16.65%
from
from
(a)
(b)
(c)
(d)
Synthesis
of
d]indolium
1-Decy1-2(1H)-methyl-benz[c,
(212)
1mmol)
(0.2g,
without
washed
for
heating
water
with
gel
60
(217)
dye
contained
in
Table
Synthesis
of
(218)
were
dissolved
in
iodide
ethanol
The product
30 minutes.
dried.
and
%
%
Characterisation
(0.44g,
(20m1)
and
and stirred
filtered
was then
data
immol)
for
(217)
off,
is
53.
2-Amino-3-carboxyethyl-4-phenyl-thiophene
(3.02g,
0.0122mo1)
and
187
(212)
and
(2.5g,
0.0122mo1)
stirred
(218)
of
product
gave
for
filtered
were
a satisfactory
acetic
and washed
data
with
bronzy/gold
(218)
The
water.
further
without
for
(100ml)
acid
The resultant
microanalysis
for
synthesis
of
dyes
(220)
2-Chloro-3,5-dinitrothiophene
(1mmol)
were
mixed
in
heating,
additional
filtered
gel
150-152°C.
Dye 221:
ethyl
for
and
is
summarised
in
acetate
2 hours.
(221)
lmmol)
(0.208g,
Purification
off.
Dye 220:
265°C.
glacial
53.
Procedure
silica
in
2 hours.
off
Characterisation
purification.
Table
heating
without
crystals
dissolved
were
(10ml)
and
crystals
by column
or
(149)
without
and stirred,
The precipitated
was achieved
(123a)
were
chromatography
then
over
60.
was obtained
(found:
was obtained
(found:
as lustrous
m/e = 412;
as golden
m/e = 438;
black
(0.18g,
platelets,
C20H20N404S requires
brown
needles
C22H22N404S requires
(0.14g,
43%),
m. p.
m/e = 412).
32%),
m/e = 438).
m. p.
262 -
188
REFERENCES
1.
J. A.
2.
R.
Pariser,
3.
J.
Griffiths,
Pople,
(London
4.
Trans.
Faraday
R. G. Parr,
J. Chem. Phys.,
"Colour
: Academic
C. Greville
49,1375,
Soc.,
21,466,
and Constitution
(1953).
organic
of
molecules",
1976).
Press,
Williams,
(1953).
Trans.
Roy.
Soc.
21,377,
Edinburgh,
(1857).
5.
W. H. Mills,
6.
L.
G. S. Brooker
7.
L.
G. S. Brooker
8.
L.
G. S. Brooker,
S. Wishart,
R.
et
et
J.
Chem. Soc.,
117,579,
(1920).
al,
J.
Am. Chem. Soc.,
62,1116,
(1940).
al,
J.
Am. Chem. Soc.,
63,3192,
(1941).
R. H. Sprague,
J.
Am. Chem. Soc.,
63,3203,
R. H. Sprague,
J.
Am. Chem. Soc.,
63,3214,
of
Synthetic
(1941).
9.
L.
G. S. Brooker,
(1941).
10.
K. Venkataraman
(London
11.
R.
H. Hartman,
"Light
(Berlin
: Springer
Colourants",
G. S. Brooker
12.
L.
13.
Kodak
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
A.
Chemical
Barker,
S. Akiyama
G. Hallas,
S. Akiyama
S. Akiyama
S. Akiyama
S. Akiyama
S. Akiyama
G. A.
A.
I.
al,
et
al,
J.
S. D. C.,
et
et
J.
al,
Tolmachev
1980).
Verlag,
(1945).
67,1875,
J.
86,
J.
al,
311,
238,
Chem. Soc.
Chem. Soc.
Dyes
al,
Bull.
al,
(1954).
(1981).
(1970).
Trans.
Perkin
329,
(1988).
(1986).
710,
Org.
Dyes and Pigments,
(1987).
(1988).
9,454,
Chem. Soc. Jpn.,
J.
3155,
I,
Chem. Commun.,
and Pigm ents,
K. H. Drexhage,
et
1307,
Chem. Soc.,
Chem. Lett.,
al,
et al,
Reynolds,
Organic
of
Am. Chem. Soc.,
Chem. Lett.,
et
et
J.
Absorption
Catalogue.
C. C. Barker,
et
Vol. VIIi
Dyes",
1978).
Press,
: Academic
Fabian,
"Chemistry
(Ed),
61,2253,
Chem.,
9,443,
(1988).
42,885,
(1988).
(1977).
189
24.
S. Watanbe,
H. Nakazumi,
S. Kado,
T.
Kitao,
Chem. Soc.,
J.
in
press.
25.
T.
G. Deligeorgieu,
N.
I.
Gadjev,
Dyes and Pigments,
12,157,
(1990).
26.
P.
F.
York
Gordon,
"Organic
P. Gregory,
: Springer-Verlag,
27.
S.
S. Malhotra,
28.
K.
Y.
Chemistry
in
(New
Colour".,
1983).
M. C. Whiting,
J.
Chem. Soc.,
3812,
Research,
(M)2319,
Chu,
J.
Griffiths,
J.
Chem.
Chu,
J.
Griffiths,
J.
Chem. Soc.
(1960).
(S)180,
(1978).
29.
K.
Y.
(1978);
30.
696,
Perkin
1083,
Trans.,
(1979).
G. G. Buckley,
Griffiths,
J.
Chem. Soc.
J.
702,
Trans.,
Perkin
(1979).
31.
K.
Tagaki,
140,
32.
M.
34.
36.
37.
Japanese
39.
40.
41.
42.
Kubo,
T.
Kitao,
J.
S.
D.
C.,
101,
Y.
Yubo,
K.
Kitao,
J.
S.
D.
C.,
102,
J.. B.
K. A.
(1986).
M.
H.
Dickey,
Bello,
et
et
J.
Thin
Hatou,
(1986).
7,93,
(1985).
1351,
H.
Tomi,
Mol.
Cryst.
Liq.
(1985).
Ann.
Liebigs.
Dickey,
Zunoya,
60,49,063
Patent
164373K.
(1989).
Kitao,
K.
III,
Griffiths,
J.
Goringe,
Chem. Letters,
122,285,
Griess,
B.
M. J.
: Chem. Abs.,
Dyes and Pigments,
al.
T.
Matsumoto,
Japanese
(1989)
01,66,288
et
M. Matsuoka,
J.
Kim,
180,305,
M. Matsuoka
P.
H.
G. G. Roberts,
Films,
Cryst.,
38.
S.
Patent
D. Heard,
S.
Y.
(1986).
Solid
35.
Matsuoka,
(1985).
Matsuoka,
232,
33.
M.
al,
al,
J.
J.
Griffiths,
(1985):
Chem. Abs.,
S. D. C.,
Chem.,
Org.
J.
(1858).
106,123,
Chem.,
(1958).
74,123,
24,187,
Chem. Soc.
103,55427.
(1959).
Chem. Common.,
1639,
190
43.
P.
Gregory,
European
Patent
280,434
(1988):
Chem. Abs.,
110,
116654K.
44.
D.
Scheltz,
45.
K.
A.
Bello,
Trans.
(II),
Hel.
Chim.
L.
Cheng,
815,
46.
M. J.
S. Dewar,
47.
J.
Park,
D.
3480,
48.
J.
S.
J.
58,1207,
(1975).
Griffiths,
J.
Perkin
(1987).
Chem. Soc.,
J.
Cohen,
2329,
(1950).
J.
R.
Lacher,
J.
Am.
Soc.,
81,
J.
R. Lacher,
J.
Am. Chem. Soc.,
84,
S. Cohen,
Chem.
(1962).
49.
R. West,
H. Y. Niu,
J.
Am. Chem. Soc.,
50.
R.
H.
D.
I.
West,
Y.
Niu,
82,6204,
Soc.,
Chem. Soc.
(1959).
D. Park,
2919,
Acta.,
51.
M. Ito,
52.
W. M. McIntyre,
Powell,
(1962).
84,1324,
Am. Chem.
J.
Evans,
M. V.
(1960).
R. West,
J.
Am. Chem. Soc.,
Chem. Phys.,
J.
M. S. Werkerna,
(1963).
85,2580,
42,3563,
(1964).
53.
N.
J.
C. Baezinger,
J.
86,3250,
Am. Chem. Soc.,
J.
Hegenbarth,
(1964).
54.
55.
M. A.
A.
Neuman,
H. Schmidt,
56.
G. Maahs,
57.
U.
58.
A.
P.
W. Ried,
Chem.,
Angew.
(1978).
869,
Synthesis,
Hengenberg,
(1966).
26,6394,
Abstr.,
78,927,
(1966).
4,097,530.
S. Patent
Treibs,
Diss.
K.
Angew.
Jacob,
Chem. Int.
Ed.
Engl.,
4,694,
(1965).
59.
60.
61.
62.
U. K.
D.
5,
(1983 )..
N.
Law,
Kuramoto,
(1989).
C.
Loutfy,
R.
K-Y
2,097,013.
Patent
F.
K.
Hsiao,
C. Bailey,
K. Natsukawa,
P.
Can.
M. Kazmaier,
J.
Chem.,
K. Asao,
Photogr.
64,2267,
27,
Sci.,
(1986).
Dyes and Pigments,
11,21,
191
63.
A.
Treibs,
K. Jacob,
Justus
Liebigs
Ann.
Chem.,
699,153,
K.
Justus
Liebigs
Ann.
Chem.,
741,101,
(1966).
64.
A.
Treibs,
Jacob,
(1970).
65.
U.
66.
K-Y
S. Patent
3,617,270
Law,
187,
S.
Caplan,
F.
C. Bailey,
K-Y
68.
K.
69.
C. Brunner,
70.
L.
Gmelin,
Ann.
71.
K.
Yamada,
M. Mizuno,
Law,
A.
543,
A.
R.
K.
Crandall,
J.
Chem. Soc.,
Dyes
9,
Pigments,
and
(1988).
67.
72.
(1971).
Bello,
Ph. D. Thesis,
Schweigger's
University
of
38,517,
J.,
(1986).
Leeds
4,1,
Y. Hirata,
Press.
(1823).
(Leipzig)[2],
Phys.
In
(1825).
Chem. Soc.
Bull.
31,
Jpn.,
(1958).
J.
Fatiadi,
H. S.
Isbell,
W. F.
Sagar,
J.
of
67A,
Res.,
153,
(1963).
73.
R. Nietzki,
74.
K.
K. Hartley,
(1989):
75.
Y.
77.
A.
79.
R.
80.
For
Schulze,
T.
D. Travis,
J.
Tsujuichi,
77,382,
Icarus,
Chem.,
Ann.
Liebigs
Aerztl.
Chem.
Soc.
47,5902,
Chem. Abs.,
G. Quadbeck,
Voelkl,
Lab,
19(2),
Jpn.,
Pure
(1953).
201,
(1971).
45,
(1973):
Chem.
72,29233v.
Abs.,
78.
(1948):
L.
L.
(1887).
110,196685j.
Inukai,
69,63,
A Treibs,
A.
A. R. Wolff,
K.
Hirata,
20,1617,2114,
Chem. Ges.,
Dtsch.
Chem. Abs.,
Chem.,
76.
Ber.
J.
J.
Fatiadi,
West,
"Oxocarbons",
example:
(New York
(1978).
100,2586,
Am. Chem.. Soc.,
: Academic
Press,
1980).
-
Japanese
Patent
61,34,092,
(1986):
Chem. Abs.,
106,41718r.
Japanese
Patent
59,14,150,
(1984):
Chem. Abs.,
102,15216y.
Japanese
Patent
61,30,590,
(1984):
Chem. Abs.,
105,124354z.
Japanese
Patent
58,173,696,
(1983):
Chem. Abs.,
100,94591b.
192
81.
S.
Yasui,
M. Matsuoka,
T.
Kitao,
10,13,
Dyes and Pigments,
(1988).
82.
U. K. Patent
83.
For example: -
84.
85.
322,169.
Japanese
Patent
01,34,791,
Japanese
Patent
63,242,682,
(1988):
Chem. Abs.,
111,31421c.
Japanese
Patent
63,267,592,
(1988):
Chem. Abs.,
111,31426h.
Japanese
Patent
63,306,091,
(1988):
Chem. Abs.,
111,87536m.
Japanese
Patent
64,00,569,
(1989):
Chem. Abs.,
111,87544n.
Japanese
Patent
01,08,093,
(1989):
Chem. Abs.,
111,68049p.
W. S. Chan,
J.
Holt,
Photochem.
R.
Wheeler,
L.
P.
Chem. Abs.,
(1989):
61,152,685
Patents
Japanese
L.
Lukes,
J.
P.
Silver,
A. J.
Kennedy,
I.
R.
(1987).
Bard,
L.
A.
Am. Chem.
J.
Soc.,
K.
Hey,
Polyhedron,
M. O'Connor,
J.
111,162880z.
and 61,152,769,
(1986):
Chem. Abs.,
20000u.
106,19999t,
89.
45,757,
M. F.
Dininny,
D. Phillips,
communication.
8,13,
88.
R.
111,164314s.
(1984).
Private
J.
R. Svensen,
Marshall,
and Photobiol.,
D.
106,7404,
87.
Chem. Abs.,
G. Nagasubramanian,
Schechtmann,
86.
F.
(1989):
I.
Mikhalenko,
Solovara,
J.
Gen.
Chem. U. S. S. R.,
986,
(1985).
90.
German
3,446,418
Patent
91.
European
Patent
92.
European
Patent
93.
For
example:
Japanese
Japanese
Japanese
Japanese
Al
(1986).
155,780
(1985).
313,943
(1989).
111,116825n.
63,301,261
(1988):
Chem. Abs.,
Patent
63,227,386
(1988):
Chem. Abs.,
111,31437n.
Patent
63,227,387
(1988):
Chem. Abs.,
111,31438p.
Patent
63,274,591
(1988):
Chem. Abs.,
111,87541j.
Patent
193
94.
W. H. Mills,
95.
A.
96.
G. N.
Schauzer,
97.
G. N.
Schauzer
J.
R. E. D. Clark,
Lowe,
J.
Chem. Soc.,
J.
Angew.
all
Chem. Soc.,
1258,
V. Mayweg,
et
J.
175,
(1936).
(1940).
Am. Chem. Soc.,
Chem. Int.
Edn.
84,
(1962).
Eng.,
3,381,
(1964).
98.
99.
S.
H.
Kim,
M. Matsuoka,
M. Yomoto,
and Pigments,
8,381,
J.
C. Hawkins,
Griffiths,
747,
Tsuchiya,
T.
Kitao,
Chem. Soc.
J.
Perkin
(II),
Trans.
(1977).
N. Kuramoto,
T.
101.
N. Nakazumi,
E. Hamada,
J.
105,26,
S.
For
D. C.,
example:
German
Kitao,
J.
98,334,
S. D. C.,
T.
Ishiguro,
(1982).
H. Shiozaki,
T.
Kitao,
(1989).
3,716,734
Patent
(1988):
Chem. Abs.,
111,31419h.
Japanese
Patent
63,209,890
(1988):
Chem. Abs.,
111,31420b.
Japanese
Patent
63,288,785
(1988):
Chem. Abs.,
111,87548s.
Japanese
Patent
63,288,786
(1988):
Chem. Abs.,
111,87549t.
103.
Y.
Kubo,
S. Sasaki,
K. Yoshida,
Chem. Lett.,
104.
Y.
Kubo,
K.
Sasaki,
H. Kataoka,
K. Yoshida,
Y.
Y.
A.
H. Kataoka,
Kubo,
F.
J.
Three
109.
110.
R. A.
M.
J.
(1987).
Chem. Soc.
(1982).
Chem. Soc.
Y. Yoshida,
J.
M. Ikezawa,
K. Yoshida,
Chem. Commun.,
50(9),
J.
N.
Y.
Russian
Dal'nikouskaya,
Chem. Soc.
Chemical
(1981).
"Six-membered
Condensed
Jeffreys,
Allum,
816,
J.
press.
V. V.
Pozharskii,
H. Richmond,
with
in
(I),
Trans.
Reviews,
108.
1563,
(1988).
Perkin
107.
H. Kataoka,
Kubo,
1457,
106.
1469,
(I),
Trans.
Perkin
105.
Dyes
(1987).
100.
102.
Y.
(New York:
Rings",
Chem. Soc.,
Abou-Zeid,
Nitrogen
Heterocyclic
2394,
Egy pt
J.
Academic
Compounds
Press,
(1955).
Chem.,
4,339,
(1972).
1958).
194
ill.
The Colour
112.
U.
Index.
Miller,
54,237,
Histochemistry,
Preiss,
A.
Franz,
H.
(1977).
113.
H. Yamamoto,
114.
European
115.
S. N.
116.
M. Ellwood,
117.
A.
Hantzsch,
Chem. Ber.,
118.
F.
Ketrmann,
S. Hempel,
119.
M.
T.
Corns,
C. R.
Bury,
121.
I.
M.
Klotz,
Chem.
Soc.,
H. H. Jaffe,
124.
L.
K.
P.
(1919).
Chem. Ber.,
A.
Fries,
R.
(1917).
50,856,
W. Meatman,
Am. Chem.
J.
T.
F.
J.
(1935).
57,2115,
Chem Ho,
Y.
130.
Izzo,
J.
Zuffanti,
F.
J.
132.
Chem.,
Org.
21,
S.
M. Mondo,
(1959).
5,27,
Tetrahedron,
Kwon,
Dyes
Kuroki,
N.
and
6,
Pigments,
(1984).
J.
Venkataraman
(London:
Pfeiffer,
German Patent,
German
S. D. C.,
"The
(Ed. ),
Academic
86,238,
Press,
(1970).
Chemistry
of
Synthetic
R. Wizinger,
Liebigs
3,422,075,
(1986).
Patent,
3,445,252,
Dyes",
1979).
(1986):
U. S. Patent,
3,299,892,
(1967).
S. Patent,
3,362,953,
(1968).
U.
Am.
(1953).
21,415,
Chem. Phys.,
133748h.
131.
J.
M. Mellody,
Ann.
Chem.,
461,132,
(1928).
129.
Soc.,
(1954).
76,5136,
Horiike,
G. Hallas,
IV,
128.
H.
Pentimalli,
321,
127.
(1982).
Leeds,
of
52,509,
W. Campbell,
observations.
(1956).
123.
T.
University
Am. Chem. Soc.,
J.
W. S. McGuire,
632,
126.
T.
(1983).
Unpublished
-
Ph. D. Thesis,
(1981).
(1951).
120.
125.
Griffiths
J.
Rogers,
73,5122,
122.
0 071 197A1,
Patent
103,4186,
Am. Chem. Soc.,
J.
K. Maruoka,
Chem. Abs.,
105,
Vol.
195
133.
U. K.
134.
S. Hünig,
135.
European
136.
K.
137.
W. Ziebenbein,
138.
H. Schwarz,
H. E.
H. E.
Chem.,
Ann.
(1989);
Griffiths,
J.
Sprenger,
599,131,
Chem. Abs.,
112,22278e.
Dyes and Pigments,
Sprenger,
(1956).
11,65,
(1988).
Angew.
Chem. Int.
Ed.
Eng.,
5,
W. Ziebenbein,
Angew.
Chem. Int.
Ed.
Eng.,
5,
(1966).
139.
German Patent
140.
H. J.
Bernd,
(10),
1201,
(1978).
University
Ph. D Thesis,
142.
U. S. Patent
2,719,861.
143.
U. S. Patent
3,013,013.
144.
L.
145.
Aldrich
Dixon,
Z. Naturforsch,
R. Peltzmann,
U. Peltzmann,
C. Blackburn,
F.
(1988).
3,631,843A1,
141.
J.
Liebigs
(1966).
894,
146.
(1964).
319,234,
Patent
Bello,
A.
893,
1,055,831,
Patent,
Internal
Catalogue
S. Whitehurst,
of
Leeds
Paper.
Chemicals.
of
Fine
J.
Chem. Soc.,
226,
(1951).
1982.
33(B),