Electronic Supplementary Material
Calix[4]arenes Bearing a Tropylium Substituent as Hosts for Organic Cations
M. FEHLINGER and W. ABRAHAM*
UV-Vis-spectra of the tropylium substituted calixarenes 9 and 10, solvatochromism of
compounds 9, 10 and 12, mass spectra of two complexes, NMR-titration curves, JOB-plots
and CIS-values of some protons of selected complexes
1
The lower acidity of compound 10 compared with 9 must be attributed to the hydrogenbond motif at the lower rim. The hydroxy group of the hydroxyphenyl tropylium subunit of 9
is involved both as hydrogen bond donor and acceptor. However, in compound 10 only the
hydrogen-bond-donor capability plays a role. The hydrogen bond motifs formed at the lower
rim of the calixarenes also play an important role for the solvatochromism observed with
compounds 9 and 10 (Scheme 1). However, hydrogen bonds can be excluded in dilute
solutions of compound 12, and the known observed negative solvatochromism is seen.
The involvement of OH-groups in hydrogen bonds plays a role in the absorption maxima both
of 9 and 10 in different solvents. The OH-group involved both as hydrogen-bond donor and
acceptor is a weaker electron donor substituent, leading to blue shift of the absorption band of
9 compared with the model compound 12. An OH-group, which can only serve as a
hydrogen-bond donor, as in compound 10, is a stronger electron donor, which leads to a red
shift of the absorption band compared with 12 and 9. Hexafluoro-i-propanol (HFIP) can only
donate strong hydrogen bonds, thus breaking intramolecular hydrogen bonds in 9 and 10.
Accordingly, the calixarenes 9 and 10 have identical UV-Vis absorption maxima in this
solvent (see Table 1).
O
O
H
H
O
O
O
H
H
H
O
H
H
O
O
PF6
9
9
O
O
R
R
O
R
R
O
O
R
( = 9a, see Scheme 3)
H
O
R
O
O
PF6
10
10
(= 10a)
Scheme 1 Hydrogen bond pattern at the lower rim of 9 and 10
2
b)
Absorbance
Absorbance
a)
Wavelength [nm]
Wavelength [nm]
Figure 1a UV-Vis spectra of Calixarene 9 in different solvents (1 = dichloromethane; 2 =
acetonitrile; 3 = 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP); 4 = water; 5 = acetone; 6 =
methanol)
Figure 1b UV-Vis spectra of Calixarene 10 in different solvents (1 = dichloromethane; 2 =
acetonitrile; 3 = 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP); 4 = water; 5 = acetone; 6 =
methanol)
Table 1 Vis-absorption maxima (nm) in different solvents
Solvent
dichloromethane
acetone
acetonitrile
methanol
water
HPF
9
473
561/447
562/441
562/461
543
457
10
498
474
467
483
464
457
12
474
458
454
452
547/448
463
3
Inte nsity (%)
10+ (100%)
10+ x11
M/z
Figure 2 ESI-MS of the mixture of 10 und 11
Inte nsity
10+ (100%)
10+ x13
(10+ )2 PF6-
m/z
Figure 3 ESI-MS of the mixture of 10 and 13
4
Figure 4 Chemical shift of the resonances of the -proton of the tropylium unit of compound
10 upon dilution. The bars denote the deviation of calculated values from the experimental
values.
5
990
chemical shift [Hz]
980
970
960
950
940
930
0
2
4
6
8
10
12
14
16
18
R = [Host]/[Guest]
a)
2660
2640
chemical shift [Hz]
2620
2600
2580
2560
2540
2520
2500
0
2
4
6
8
10
12
14
16
18
R = [Host]/[Guest]
b)
Figure 5 1H NMR titration of the complex 10/15
a) NCH3 protons; b) Tropylium proton
6
X(g ue st) -  (NMe2 
X(g ue st) -  (Tro p -
X(guest
X(guest
Figure 6 JOB-plot for the complex 10/15; tropylium proton – left, methyl protons right
Table 2 CIS-values of selected proton resonances of host-guest complexes as calculated by
the help of NMR-titration
/ppm
host
14
15
3
NMe: 1.2
NMe2: 0.18
Tropylium--H:
Tropylium-
Tropylium--H:
3.3
: 0.57
0.9
NMe: 1.4
NMe2: 0.35
Tropylium--H:
Tropylium--H:
Tropylium--H:
0.6
not usable
0.9
NMe: 1.2
NMe2: 0.2
Tropylium--H:
Tropylium--H:
3.4
1
NMe: 1.3
NMe2: 0.3
Tropylium--H:
Tropylium--H:
not usable
0.8
4
6
7
8
16
17
NMe : 0.45
MeCO: 0.16
NMe: not usable
Tropylium--H:
1.8
7
10
NMe: 0.8
NMe2: 0.2
Tropylium--H:
NMe : 0.54
Tropylium--H:
Tropylium--
0.3
MeCO: 0.14
1.6
H
Me: 0.09
8