Thermotropic liquid crystals of 1H-imidazole amphiphiles showing hexagonal columnar and micellar cubic phases

Article abstract of DOI:10.1016/j.tetlet.2007.07.187

The linear and polycatenar type 1H-imidazole amphiphiles showing a strong self-assembly tendency to build various supramolecular structures in bulk were synthesized by the esterification reaction of 4′-alkyloxy phenols (for 1-4) and hydroxyphenyl trialkyl

Full text of DOI:10.1016/j.tetlet.2007.07.187

Tetrahedron Letters 48 (2007) 6839–6844
Thermotropic liquid crystals of 1H-imidazole amphiphiles
showing hexagonal columnar and micellar cubic phases
Sang Hyuk Seo,a Jun Ha Park,a Gregory N. Tewb and Ji Young Changa,*
aSchool of Materials Science and Engineering, and Hyperstructured Organic Materials Research Center,
College of Engineering ENG445, Seoul National University, Seoul 151-744, Republic of Korea
bPolymer Science and Engineering Department, University of Massachusetts, Amherst, MA 01003, USA
Received 30 June 2007; revised 24 July 2007; accepted 27 July 2007
Available online 1 August 2007
Abstract—The linear and polycatenar type 1H-imidazole amphiphiles showing a strong self-assembly tendency to build various
supramolecular structures in bulk were synthesized by the esterification reaction of 40-alkyloxy phenols (for 1–4) and hydroxyphenyl
trialkyloxybenzoates (for 5–7) with 4-chlorocarbonyl imidazole. The linear 1H-imidazole amphiphiles formed thermotropic smectic
phases, but compound 4 with an ethyl group instead of hydrogen on 1N did not show a mesophase. The polycatenar type 1H-imid-
azole amphiphiles (5–7) formed thermotropic hexagonal columnar and cubic phases. A phase transition was observed from a colum-
nar phase to a cubic phase as the temperature increased on heating, and vice versa on cooling. In the POM study for compounds 5–
7, optically isotropic phases first appeared on cooling from the isotropic melts, and then birefringent mesophases with a nonspecific
texture appeared on further cooling. The X-ray analysis shows that the optically isotropic phases were very likely micellar cubic
phases with Pm3n symmetry. The birefringent phases were confirmed as hexagonal columnar phases.
Ó 2007 Elsevier Ltd. All rights reserved.
Amphiphilic molecules have been widely used as a
building block for the synthesis of supramolecular mate-
rials.1–5 They are self-assembled into various supramole-
cular structures such as a micelle, ellipsoid, cylinder
and vesicle in aqueous or organic solutions. There have
been also reported highly ordered liquid crystalline
phases of the amphiphiles in solutions as well as in
bulk.6,7 We previously reported the self-assembly of
1H-imidazole amphiphiles in solution, forming organo-
gels, micelles or lyotropic liquid crystals depending on
their molecular structures. For example, the linear
amphiphiles having an imidazole head connected to a
hydrophobic alkyloxyphenyl group through an ester
linkage formed organogels.8,9 The polycatenar 1H-imid-
azole amphiphiles formed lyotropic liquid crystals
showing columnar hexagonal structures and bundles at
the surface of silicon. This strong tendency of 1H-imid-
azole amphiphiles to self-assemble in solution is largely
indebted to its capability of acting as both a proton
donor and acceptor in forming hydrogen bonding. In
biological systems, imidazole and its derivatives are
known to play important roles as the proton donor
and/or acceptor.10–12 Recently, ionic liquid crystals
based on imidazolium salts gained much attention as
reaction solvents.13–16
In this Letter, we studied on thermotropic liquid crystal-
line properties of 1H-imidazole amphiphiles. Very
interestingly, polycatenar type amphiphiles with a
1H-imidazole head show transitions of hexagonal
columnar phases to cubic phases on heating and vice
versa on cooling, while linear amphiphiles show smectic
phases. Cubic phases17–19 represent highly ordered
supramolecular arrangements with optically isotropic
properties. Cubic phases have been frequently found in
lyotropic liquid crystalline systems, comprising lipid
(or surfactant) and solvent, but relatively few com-
pounds with thermotropic cubic mesophases (e.g., poly-
hydroxy derivatives, folic acid derivatives, cone-shaped
monodendrons and rod-coil molecules) are known.19–23
Discotic liquid crystals are attractive due to their poten-
tial applications in devices such as photovoltaic solar
cells24,25 and electro-luminescent displays.26 Typical dis-
cotic liquid crystalline compounds consist of disk-like
aromatic rings27,28 as a core and peripheral alkyl chains
but there have been also reported discotic liquid crystals
formed by supramolecular assemblies of molecules other
than discotic ones.29–31
*
Corresponding author. Tel.: +82 2 880 7190; fax: +82 2 885 1748;
e-mail: jichang@snu.ac.kr
0040-4039/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2007.07.187

6840
S. H. Seo et al. / Tetrahedron Letters 48 (2007) 6839–6844
1H-Imidazole amphiphiles were prepared according to
our previous reports.8,9 Linear 1H-imidazole amphi-
philes (1–3) were synthesized by the esterification reac-
tion of 40-alkyloxy phenol with 4-chlorocarbonyl
imidazole under basic conditions.32 For comparison,
compound 4 was prepared, where 1N of the imidaz-
ole head was blocked by ethyl group.33 Polycatenar
1H-imidazole amphiphiles (5–7) were obtained by the
esterification reaction of hydroxyphenyl trialkyloxy-
benzoates with 4-chlorocarbonyl imidazole (Scheme
enthalpy value of 26.6 J/g occurred. In POM analysis,
a birefringent phase was observed from 132 °C to
111 °C on cooling (Fig. 1a). Compounds 1 and 3 also
show monotropic transitions similar to those of com-
pound 2. However, compound 4 with an ethyl group
instead of hydrogen on 1N did not show a mesophase,
supporting the idea that hydrogen bonding is critical
in these systems. Polycatenar compounds 5–7 having
one more phenyl group and two more side chains, com-
pared to compounds 1–3, exhibited both hexagonal
columnar and cubic phases. A phase transition was
observed from a columnar phase to a cubic phase as
the temperature increased on heating, and vice versa
on cooling. Compound 7 show a crystal to hexagonal
columnar phase transition at 48 °C with an enthalpy
value of 3.6 J/g, a hexagonal columnar phase to cubic
phase transition at 80 °C with an enthalpy value of
14.0 J/g, and a cubic phase to isotropic liquid transition
at 114 °C with an enthalpy value of 0.42 J/g on heating.
In the subsequent cooling cycle, an isotropic to cubic
phase transition at 112 °C with an enthalpy value of
0.05 J/g, a cubic phase to hexagonal columnar phase
transition at 86 °C with an enthalpy value of 10.4 J/g,
and a hexagonal columnar phase to crystal transition
at 24 °C with an enthalpy value of 0.14 J/g occurred.
Compounds 5 and 6 having shorter alkyl chains also
showed enantiotropic transitions similar to those of
compound 7. Phase transition temperatures and corre-
sponding enthalpy values for compounds 1–3 and 5–7
are given in Table 1. In the POM study, only optically
isotropic phases appeared initially on cooling from
the isotropic melts of compounds 5–7, which is charac-
teristic of a cubic structure. Birefringent mesophases
with a nonspecific texture began to form on further cool-
ing. A typical POM image obtained from 7 is shown in
Figure 1b.
1
1).34 The structures were fully characterized by H and
13C NMR spectroscopy and elemental analysis.
The thermotropic properties of compounds 1–7 were
investigated by polarizing optical microscopy (POM),
differential scanning calorimetry (DSC) and X-ray dif-
fraction (XRD). In the DSC analysis, compounds 1–3
show monotropic mesophases. Compound 2 show a
crystal to crystal transition at 128 °C with an enthalpy
value of 7.9 J/g and a melt transition at 155 °C with
an enthalpy value of 52.6 J/g on heating. In the subse-
quent cooling cycle, an isotropic to liquid crystal transi-
tion at 132 °C with an enthalpy value of 23.0 J/g and a
liquid crystal to crystal transition at 111 °C with an
O
C
O
C
NaH
DMF
+
HO
OR
HN
Cl
HN
O
OR
N
N
R =
CH2(CH2)6CH3
1
CH2(CH2)8CH3
CH2(CH2)10CH3
2
3
O
C
O
H3CH2C
NaH
DMF
HN
HN
O
OR
+
BrCH2CH3
N
C
O
OR
N
N
N
R =
4
CH2(CH2)10CH3
OR
COCl
+
HO
OOC
OR
The structures of the liquid crystals of 1–3 were investi-
gated by using an X-ray diffraction technique. In the
small angle region, only one sharp reflection peak
OR
HN
OR
NaH
DMF
˚
COO
OOC
OR
OR
corresponding to the d spacing of 31.5 A (for 1),
N
˚
˚
33.4 A (for 2) and 34.5 A (for 3) appeared (Fig. 2).
R =
CH2(CH2)6CH3
CH2(CH2)8CH3
CH2(CH2)10CH3
5
6
7
Since the lengths of the molecules were calculated to be
˚
˚
˚
19.9 A (for 1), 22.0 A (for 2) and 24.4 A (for 3), respec-
tively, using a simple molecular modeling (MM2) meth-
od, it seems that they existed in a dimer form with
Scheme 1.
Figure 1. Polarizing optical micrographs of (a) compound 2 and (b) 7 obtained at 130 °C and 65 °C, respectively, on cooling at a rate of 5 °C minꢀ1
.

S. H. Seo et al. / Tetrahedron Letters 48 (2007) 6839–6844
6841
Table 1. Phase transition temperatures and enthalpy values (in parentheses) of 1H-imidazole amphiphiles as determined by DSC (scan rate:
5 °C minꢀ1) or POMa
Compound
Phase transition temperature (°C) and D H (J gꢀ1
)
2nd heating
2nd cooling
1
2
3
5
6
7
Cr 125 (5.4) Cr 154 (51.4) I
Cr 128 (7.9) Cr 155 (52.6) I
Cr 120 (17.4) Cr 146 (41.8) I
Cr 35 (3.9) Colh 95 (17.7) Cub 120 (0.04) I
Cr 23 (2.0) Colh 82 (13.1) Cub 115 (0.02) I
Cr 48 (3.6) Colh 80 (14.0) Cub 114 (0.42) I
I 131 (13.4) Sm 110 (27.8) Cr
I 132 (23.0) Sm 111 (26.6) Cr
I 134 (25.3) Sm 112 (27.9) Cr
I 115 (0.01) Cub 94 (7.9) Colh 23 (0.04) Cr
I 114b Cub 91 (7.1) Colh 27 (0.06) Cr
I 112 (0.05) Cub 86 (10.4) Colh 24 (0.14) Cr
a Abbreviations: Cr = crystalline; Sm = smectic; I = isotropic; Colh = hexagonal columnar; Cub = cubic mesophase.
b Determined by POM.
Figure 2. X-ray diffractograms for the smectic phases of (a) compound
1, (b) compound 2 and (c) compound 3 obtained at 120 °C on the
second cooling.
Figure 3. X-ray diffractograms for the hexagonal columnar phases of
(a) compound 5, (b) compound 6 and (c) compound 7 obtained at
40 °C on cooling.
the molecules are arranged in a disk to form a longer
mesogen via hydrogen bonding between successive imid-
azole moieties as shown in Figure 5 (left).8,9,35 Chain
structures of hydrogen bonded imidazole molecules
have been found in the crystal state and in the solution
state.8,31,35 Assuming a density of q = 1 g cmꢀ3, the
number (n) of molecules arranged side by side in a single
slice of the columns with a thickness (h) of approxi-
mately 0.45 nm was estimated according to Eq. 1.36
hydrogen bonding between imidazole moieties, forming
smectic structures. The observed layer distances were
smaller than twice the molecular lengths, indicating
either a tilted arrangement of the molecules or interdig-
itation of the alkyl chains.
The birefringent phases of polycatenar 1H-imidazole
amphiphiles 5–7 were confirmed as columnar hexagonal
phases. In the small angle X-ray diffractograms obtained
at 40 °C on cooling, three reflection peaks correspond-
p
n ¼ ða2Þ 3=2hðNA=MÞq
ð1Þ
˚
ing to the d spacings of 46.0, 26.7 and 23.4 A (for 5)
˚
and 47.4, 27.8 and 23.6 A (for 6) and 50.7, 28.8 and
˚
25.4 A (for 7) appeared (Fig. 3). These reflections are
The parameter a is the hexagonal lattice parameter, NA
the Avogadro constant and M the molecular mass. The
number of molecules in a disk at the thermotropic
columnar state was calculated to be about 9–10.
indexed in sequence as (100), (110) and (200) of a
hexagonal columnar lattice with the lattice parameter
of a = 53.1 (for 5), 54.8 (for 6) and 58.5 (for 7). In addi-
tion, a diffuse halo is observed in the wide-angle region
˚
at 4.55 (for 5), 4.52 (for 6) and 4.39 A (for 7).
The X-ray analysis shows that the optically isotropic
phases were very likely micellar cubic phases with
Pm3n symmetry (Fig. 4).19–22 In the small angle X-ray
diffractogram of compound 5 obtained at 100 °C on
cooling, two reflections corresponding to d spacings of
The lengths of the molecules were calculated to be
˚
˚
˚
25.8 A (for 5), 28.7 A (for 6) and 31.0 A (for 7), respec-
tively, using the MM2 method, which were close to the
radii of the corresponding disks determined by X-ray
analysis. Judging from these results and the structural
motif of a polycatenar molecule, it is very likely that
˚
41.0 and 36.2 A were observed. These reflections are in-
dexed in sequence as (200) and (210) of a cubic phase
˚
with a lattice parameter of a = 82.0 A. Four reflections

6842
S. H. Seo et al. / Tetrahedron Letters 48 (2007) 6839–6844
Figure 5. Schematic representation of a hexagonal columnar to cubic
phase transition.
connected to a hydrophobic alkyloxyphenyl or a
hydroxyphenyl trialkyloxybenzoate group through an
ester linkage. The polycatenar 1H-imidazole amphi-
philes formed thermotropic liquid crystals having hexa-
gonal columnar and cubic structures. The transitions
from a columnar mesophase to a cubic phase were
observed as the temperature increased on heating, and
vice versa on cooling. The linear type 1H-imidazole
amphiphiles formed thermotropic smectic phases. When
hydrogen on 1N of an imidazole ring was substituted by
an ethyl group, the compound did not show liquid crys-
tal phase, strongly suggesting that the capability of a
1H-imidazole to act as a proton donor as well as an
acceptor in forming hydrogen bonding plays a major
role in its self-assembly.
Figure 4. X-ray diffractograms for the cubic phases of (a) compound 5
obtained at 100 °C, (b) compound 6 obtained at 110 °C and (c)
compound 7 obtained at 95 °C on cooling.
corresponding to d spacings of 47.7, 42.2, 39.2 and
˚
˚
33.6 A for 6 at 110 °C and 49.0, 44.3, 40.9 and 34.7 A
for 7 at 95 °C appeared. The relative positions of these
reflections are 4, 5, 6 and 8, which is in good
agreement with the (200), (210), (211) and (220) reflec-
tions of cubic phase with Pm3n symmetry with lattice
constants of 95.4 A for 6 and 98.0 A for 7. Assuming
a density of q = 1 g cmꢀ3, the number (ncell) of mole-
cules in each unit cell of the cubic lattice was estimated
according to Eq. 2.36
p
p
p
p
˚
˚
ncell ¼ V cellðNA=MÞq
ð2Þ
Acknowledgements
The parameter Vcell is the volume of unit cell of cubic
lattice, NA the Avogadro constant and M the molecular
mass. The number of molecules in each unit cell of the
cubic lattice (ncell) at the cubic state is 479 for 5, 673
for 6 and 658 for 7.
Financial supports from the Hyperstructured Organic
Materials Research Center at Seoul National University
and the Ministry of Commerce, Industry and Energy,
Korea are gratefully acknowledged. The work at the
University of Massachusetts was supported by the
NSF through the MERSEC (DMR 9400488).
Since the molecular lengths of the amphiphiles were
much smaller than the lattice parameters (e.g., the cubic
˚
phase of 7 has a lattice parameter of a = 98.0 A, while
˚
the calculated molecular length is 31.0 A), the possibility
References and notes
of the arrangement of spherical micelles in a primitive
cubic cell were excluded. Under similar circumstances,
Fontell et al. and Tschierske et al. proposed a thermo-
tropic micellar cubic phase in which eight short rod-like
aggregates (inverted micelles) formed a cubic unit cell
(Pm3n). One of these rod-like micelles is located at each
corner of the unit cell, one in the center and the other
two on each face of the unit cell.23,37,38 We presume that
the polycatenar 1H-imidazole amphiphiles reported here
also formed the cubic lattices built up by eight short rod-
like micelles with each micelle consisting of approxi-
mately 60 (for 5), 84 (for 6) and 82 (for 7) individual
molecules (Fig. 5 (right)). The Pm3n lattice seems to
be the generally favoured packing motif of rod-like or
spherical micelles as it provides a dense packing with
minimum interfaces.20
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1H-imidazole amphiphiles where an imidazole head was

S. H. Seo et al. / Tetrahedron Letters 48 (2007) 6839–6844
6843
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31.7, 29.0, 28.7, 22.9, 20.0, 14.5. IR (KBr pellet, cmꢀ1):
3141, 3011, 2920, 2850, 2654, 2593, 1728, 1508, 1449, 1336,
1199, 979. Compound 2: Yield 0.92 g (55%). 1H NMR
(300 MHz, DMSO): d 12.82 (s, 1H, NH), 8.03, 7.88 (s, 2H,
imidazole ring protons), 7.10, 6.95 (dd, 4H, ArH), 3.96 (t,
2H, ArOCH2), 1.73–1.28 (m, 16H, CH2), 0.85 (t, 3H,
CH3). 13C NMR (75 MHz, DMSO): d 164.4, 139.1, 133.6,
120.5, 117.2, 85.3, 75.1, 74.6, 65.6, 32.2, 29.6, 29.5, 29.3,
28.7, 23.1, 20.0, 14.5. IR (KBr pellet, cmꢀ1): 3141, 3011,
2920, 2851, 2654, 2593, 1729, 1508, 1447, 1338, 1199, 977.
Compound 3: Yield 0.93 g (52%). 1H NMR (300 MHz,
DMSO): d 12.80 (s, 3H, NH), 8.05, 7.88 (s, 2H, imidazole
ring protons), 7.09, 6.96 (dd, 4H, ArH), 3.96 (t, 2H,
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ArOCH2), 1.70-1.25 (m, 20H, CH2), 0.86 (t, 3H, CH3). 13
C
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117.0, 85.0, 74.8, 74.4, 65.4, 32.1, 29.8, 29.7, 29.5, 29.3,
29.1, 28.5, 22.9, 19.8, 14.3. IR (KBr pellet, cmꢀ1): 3152,
3010, 2917, 2851, 2654, 2585, 1733, 1507, 1446, 1342, 1199,
982.
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33. Compound 4: This compound was prepared according to
our previous report.8 To a solution of compound 3 (0.2 g,
0.49 mmol) and sodium hydride (0.015 g, 0.54 mmol) in
DMF (15 mL) was added 1-bromoethane (0.15 mL,
1.47 mmol) under nitrogen. The reaction mixture was
stirred for 24 h at 90 °C. After removal of precipitates by
filtration, the filtrates were concentrated to dryness by
evaporation under reduced pressure. The product was
isolated by column chromatography on silica gel (EA/n-
hexane = 2/1); yield 0.19 g (90%). 1H NMR (300 MHz,
DMSO): d 7.88, 7.58 (s, 2H, imidazole ring protons), 7.10,
6.90 (dd, 4H, ArH), 4.07 (q, 2H, N–CH2), 3.94 (t, 2H,
ArOCH2), 2.17 (t, 3H, N–CH2CH3), 1.75–1.27 (m, 20H,
CH2), 0.88 (t, 3H, CH3). 13C NMR (75 MHz, DMSO): d
164.5, 139.3, 133.4, 120.4, 117.2, 85.1, 74.8, 74.4, 65.4,
39.9, 32.1, 29.8, 29.7, 29.5, 29.3, 29.1, 28.5, 22.9, 19.8, 16.4,
14.3. IR (KBr pellet, cmꢀ1): 3101, 2923, 2852, 1740, 1506,
1386, 1245, 1191, 1171, 1080, 966.
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2669.
34. Compounds 5–7: These compounds were prepared accord-
ing to our previous report.9 A typical procedure is as
follows. To a solution of 4-hydroxyphenyl 3,4,5-tris(n-
octan-1-yloxy)benzoate9 (1 g, 1.7 mmol) in DMF (50 mL)
was added sodium hydride (0.05 g, 2.0 mmol). After
stirring for 1 h at room temperature, 4-chlorocarbonyl
imidazole (1.24 g, 7.4 mmol) was added. The solution was
stirred for 24 h at 90 °C. After filtration and evaporation,
the product (compound 5) was isolated by column
chromatography on silica gel (THF/n-hexane = 2/1 v/v)
and further purified by recrystallization from THF/n-
hexane; (65 % yield). 1H NMR (300 MHz, CDCl3): d 7.92,
7.84 (s, 2H, imidazole ring protons), 7.41 (s, 2H, ArH),
7.27 (dd, 4H, ArH), 4.05 (t, 6H, ArOCH2), 1.29–1.86 (m,
36H, CH2), 0.88 (t, 9H, CH3). 13C NMR (75 MHz,
CDCl3): d 165.47, 161.30, 153.22, 148.69, 148.28, 143.41,
138.10, 123.80, 123.07, 122.98, 108.87, 73.87, 69.53, 32.11,
32.03, 31.12, 30.57, 29.72, 29.56, 29.53, 29.49, 26.31, 26.26,
22.90, 22.87, 13.80. IR (KBr pellet, cmꢀ1): 3113, 3078,
2925, 2663, 2598, 1732, 1504, 1336, 1178, 1127, 976.
31. Shu, W.; Valiyaveettil, S. Chem. Commun. 2002, 1350.
32. Compounds 1–3: These compounds were prepared accord-
ing to our previous report.8 A typical procedure is as
follows: 4-Imidazole carboxylic acid (1 g, 9 mmol) in
benzene (10 mL) was stirred at room temperature, and
then thionyl chloride (10 mL) dissolved in benzene
(10 mL) was added slowly. The mixture was refluxed for
10 h. After evaporation, the product (4-chlorocarbonyl-
imidazole) was dried and used for the next reaction
without further purification. To a solution of 40-octyloxy
phenol (1 g, 4.40 mmol) and sodium hydride (0.13 g,
4.84 mmol) in DMF (50 mL) was added 4-chlorocarbonyl-
imidazole (0.83 g, 4.84 mmol) under nitrogen. The reac-
tion mixture was stirred for 24 h at 90 °C. After removal
of precipitates by filtration, the filtrates were concentrated
to dryness by evaporation under reduced pressure. The
product (compound 1) was isolated by column chroma-
tography on silica gel (THF/n-hexane = 3/1); yield 0.93 g
(60%). 1H NMR (300 MHz, DMSO): d = 12.82 (s, 1H,
NH), 8.03, 7.88 (s, 2H, imidazole ring protons), 7.10, 6.95
(dd, 4H, ArH), 3.96 (t, 2H, ArOCH2), 1.73–1.28 (m, 12H,
CH2), 0.85 (t, 3H, CH3). 13C NMR (75 MHz, DMSO): d
164.4, 139.1, 133.6, 120.5, 117.2, 85.3, 75.1, 74.6, 65.6,
1
Compound 6: H NMR (300 MHz, CDCl3): d 7.92, 7.84
(s, 2H, imidazole ring protons), 7.41 (s, 2H, ArH), 7.26
(dd, 4H, ArH), 4.05 (t, 6H, ArOCH2), 1.29–1.86 (m, 48H,
CH2), 0.87 (t, 9H, CH3). 13C NMR (75 MHz, CDCl3): d
165.44, 160.82, 153.22, 148.70, 148.22, 143.42, 138.08,
123.78, 123.03, 122.96, 108.86, 73.85, 69.53, 32.15, 32.12,
30.56, 29.94, 29.90, 29.88, 29.84, 29.79, 29.61, 29.55, 29.52,
26.30, 26.27, 22.90, 14.31. IR (KBr pellet, cmꢀ1): 3113,
3068, 2852, 2666, 2600, 1735, 1502, 1338, 1180, 1122, 976.
1
Compound 7: H NMR (300 MHz, CDCl3): d 7.92, 7.84
(s, 2H, imidazole ring protons), 7.41 (s, 2H, ArH), 7.26
(dd, 4H, ArH), 4.05 (t, 6H, ArOCH2), 1.29–1.86 (m, 60H,

6844
S. H. Seo et al. / Tetrahedron Letters 48 (2007) 6839–6844
CH2), 0.87 (t, 9H, CH3). 13C NMR (75 MHz, CDCl3): d
35. Munch, W.; Kreuer, K.-D.; Silvestri, W.; Maier, J.;
¨
165.45, 160.65, 153.22, 148.71, 148.20, 143.43, 138.06,
123.77, 123.02, 122.96, 108.86, 73.85, 69.53, 32.15,
32.13, 30.57, 29.94, 29.91, 29.87, 29.85, 29.79, 29.62,
29.57, 29.53, 26.31, 26.28, 22.90, 14.3. IR (KBr pellet,
cmꢀ1): 3113, 3078, 2852, 2664, 2598, 1733, 1504, 1337,
1177, 1121, 976.
Seifert, G. Solid State Ionics 2001, 145, 437.
36. Borisch, K.; Diele, S.; Go¨ring, P.; Kresse, H.; Tschierske,
C. J. Mater. Chem. 1998, 8, 529.
37. Fontell, K.; Fox, K. K.; Hansson, E. Mol. Cryst. Liq.
Cryst. Lett. Sect. 1985, 1, 9.
38. Fontell, K. Colloid Polym. Sci. 1990, 268, 264.