EMISSION AND ABSORPTION SPECTRA OF EU(III)
TETRAMETHLPYRIDYLPORPHYRIN IN MONOLITHIC GELS
PREPARED BY SOL-GEL METHOD
Joanna DARGIEWICZ-NOWICKA, Magdalena MAKARSKA and
Stanisław RADZKI
DEPARTMENT OF INORGANIC CHEMISTRY
The porphyrins have become an indispensable component in the evolution of
living organisms, due to many types of chemical reactions, characteristic of this
group of compounds, such as: coordination, polymerisation, aggregation, oxidation
and reduction, catalysis, sorption and photochemical changes [1]. The entrapment of
organic reagents into sol-gel matrices and coatings has been the objective of much
research since Avnir and co-workers pointed out the role of such systems for sensing
purpose [2]. The sol-gel immobilisation of porphyrins in suitable matrices has been
reported in literature due
to the importance of
1
.
1
these systems from many
A
S
o
r
e
t
b
a
n
d
Q
b
a
n
d
1
.
0
~
1
5
x
points of interest, such
H
T
M
e
P
y
P
0
.
9
as: chemical and bio0
.
8
chemical sensing, optical
0
.
7
limiting,
hole-burning
E
u
T
M
e
P
y
P
(
a
c
a
c
)
0
.
6
and catalysis [3, 4].
0
.
5
Here we present our
E
u
T
M
e
P
y
P
(
a
c
a
c
)
0
.
4
study on the enca0
.
3
psulation
of
water0
.
2
soluble
free-base
0
.
1
H2TMePyP
and
its
3
0
0
3
2
5
3
5
0
3
7
5
4
0
0
4
2
5
4
5
0
4
7
5
5
0
0
5
2
5
5
5
0
5
7
5
6
0
0
6
2
5
6
5
0
6
7
5
7
0
0
complex with Eu(III) in

[
n
m
]
xerogels prepared by the
sol-gel method. The
Eu(III)TMePyP(acac) complex was prepared by the method described earlier [5].
The monolith samples with the diameter of about 10 x 10 x 15 mm were prepared by
tetraethoxysilane (TEOS) hydrolysis. We investigated their absorption and emission
spectroscopic properties compare with the spectra of the same compounds in various
solvents. The spectra of europium complex were compared with those of free-base
porphyrins. The absorption spectra of the: H2TMePyP (solid), Eu(III)TMePyP(acac)
(dotted), and partially decomposed Eu(III)TMePyP(acac) (dashed lined) in monlithic
sol-gel material are shown above.
The uv absorbance spectra illustrate the characteristic spectral changes that
accompany porphyrin metallation. When we compare spectra of free base porphyrin
4
2
8
n
m
5
2
0
n
m
2
5
5
3
n
m
5
9
0
n
m
5
4
2
n
m
4
1
7
n
m
5
5
0
n
m
4
2
6
n
m
(
p
a
r
t
l
y
d
e
c
o
m
p
o
s
e
d
)
6
4
6
n
m
with spectra of their Eu(III)
complexes we can observed

4
2
3
n
m
e
x
c
.=
only 10 nm shift of Soret
E
u
T
M
e
P
y
P
(
a
c
a
c
)
band, while dramatical
p
a
r
t
l
y
d
e
c
o
m
p
.
changes in the Q band
E
u
C
l
3
H
T
M
e
P
y
P
2
could be noticed. The Q
E
u
T
M
e
P
y
P
(
a
c
a
c
)
band of the free base
porphyrin consists of four
components:
Qx(0,0),

[
n
m
]
Qx(1,0),
Qy(0,0)
and

4
4
3
n
mE
e
x
c
.=
u
T
M
e
P
y
P
(
a
c
a
c
)
Qy(1,0)
which
are
associated with D2h (mmm)
symmetry while in the
H
T
M
e
P
y
P
2
spectra
of
Eu(III)
E
u
T
M
e
P
y
P
(
a
c
a
c
)
p
a
r
t
l
y
d
e
c
o
m
p
.
porphyrins [symmetry D4h
(4 mmmm)] only one
E
u
C
l
3
component
Qy(0,0)
is
observed.

[
n
m
]
The
luminescence
E
u
T
M
e
P
y
P
(
a
c
a
c
)

5
3
0
n
m
e
x
c
.=
p
a
r
t
l
y
d
e
c
o
m
p
.
properties of porphyrin
E
u
T
M
e
P
y
P
(
a
c
a
c
)
E
u
C
l
3
e
m
i
s
s
i
o
n
n
o
o
b
s
e
r
v
e
d
complexes with rare earth
metals have been reported,
but strong emission was
observed only for Sc, Y,
H
T
M
e
P
y
P
2
Gd, Lu and Yb. Here we
report for the first time

[
n
m
]
strong emission of Eu(III)
porphyrin in monolithic silica. The fluorescence spectra of H2TMePyP and Eu
complex are shown in the Fig. on the left. They are compared with the spectra of
silica doted with europium chloride and with the complex which was partially
decomposed. The compounds were excited with different wavelength. It can be
noticed that strong fluorescence of europium porphyrin is observed under excitation
in Soret band, while at the same time emission neither free-base porphyrin nor
europium chloride does not occur. It can be explained by the strong interaction of the
Eu(III)TMePyP(acac) with the silica.
4 [a.u]
4
.
0
0
3
.
7
5
6
0
4
n
m
3
.
5
0
6
5
3
n
m
7
1
6
n
m
3
.
2
5
6
5
4
n
m
3
.
0
0
2
.
7
5
2
.
5
0
2
.
2
5
Relativeintensityx10
2
.
0
0
1
.
7
5
1
.
5
0
1
.
2
5
1
.
0
0
0
.
7
5
6
5
0
n
m
0
.
5
0
0
.
2
5
0
.
0
0
4
7
5
5
0
0
5
2
5
5
5
0
5
7
5
6
0
0
6
2
5
6
5
0
6
7
5
7
0
0
7
2
5
7
5
0
7
7
5
8
0
0
7
5
0
7
7
5
8
0
0
7
5
0
7
7
5
8
0
0
4 [a.u]
4
.
0
3
.
5
3
.
0
5
5
6
n
m
6
5
8
n
m
2
.
5
Relativeintensityx10
2
.
0
7
1
9
n
m
6
2
0
n
m
1
.
5
6
5
2
n
m
1
.
0
0
.
5
0
.
0
4
7
5
5
0
0
5
2
5
5
5
0
5
7
5
6
0
0
6
2
5
6
5
0
6
7
5
7
0
0
7
2
5
6 [a.u]
1
.
0
5
5
4
n
m
0
.
9
0
.
8
0
.
7
6
5
5
n
m
0
.
6
Relativeintensityx10
0
.
5
7
1
5
n
m
0
.
4
0
.
3
0
.
2
0
.
1
0
.
0
4
7
5
5
0
0
5
2
5
5
5
0
5
7
5
6
0
0
6
2
5
6
5
0
6
7
5
7
0
0
7
2
5
References:
[1] L. R. Milgrom, “The colors of life: an introduction to the chemistry of
porphyrins and related compounds”, Oxford University Press, UK, 1997.
[2] R. Zusman, C. Rotman, and D. Avenir, J. Non-Cryst. Solids, 122 (1990) 107.
[3] S.-K. Lee and I. Okura, Anal. Chim. Acta, 342 (1997) 181.
[4] S. M. Arabei, Veret-Lamarnier and J.P. Galaup, Chem. Pys., 216 (1997) 163.
[5] S. Radzki , P. Krausz, S. Gaspard, C. Giannotti, Inorg. Chimica Acta, 138, (1987)
139.