(2H, d), 7.70 (2H, d), 8.12 (2H, d), 8.23 (2H, d) ppm; 13C NMR
(CDCl3) d: 14.06 (CH3), 20.08 (CH-CH3), 22.58 (CH2-CH3),
25.39 (CH2-CH2CH3), 25.45 (2 ꢀ cyclohexyl CH2), 25.76 (CH2),
25.90 (CH2), 26.02 (CH2), 28.63 (1 ꢀ cyclohexyl CH2), 29.04 (2
ꢀ cyclohexyl CH2), 29.15 (CH2), 29.21 (CH2), 29.37 (CH2), 29.47
(3 ꢀ CH2), 29.53 (CH2), 31.72 (CH2), 36.05 (CH2CH2-CH),
43.26 (cyclohexyl CH), 64.23 (CH2O), 68.14 (CH2O), 71.93 (O-
CH(CH3)CH2), 114.98 (2 ꢀ Ar-CH), 121.70 (2 ꢀ Ar-CH),
126.63 (2 ꢀ Ar-CH), 127.04 (Ar-C), 128.39 (2 ꢀ Ar-CH), 128.50
(Ar-C), 130.78 (2 ꢀ Ar-CH), 131.13 (2 ꢀ Ar-CH), 131.82 (Ar-C),
146.26 (Ar-C), 154.50 (Ar-C), 159.64 (Ar-C), 164.64 (C]O),
165.51 (C]O), 176.24 (C]O) ppm; IR (neat) nmax: 764, 825,
887, 1018, 1064, 1165, 1188, 1265, 1465, 1504, 1597, 1710, 1728,
Fig. 3 Target materials for investigation.
2. Experimental
The mesogen was prepared by initial alkylation of 4-hydroxy-40-
cyanobiphenyl with 11-bromoundecanol followed by base hydro-
lysis of the nitrile group with sodium hydroxide in ethanol to yield
the carboxylic acid 3. Compound 3 was esterified with the appro-
priate phenol 4a–c using 1-(3-dimethylaminopropyl)-3-ethyl car-
bodiimide$HCl (EDAC) and N,N-dimethylaminopyridine
(DMAP) in dichloromethane and dimethyformamide to give the
mesogen5a–c. Asubsequentesterificationofcompounds5a–cwith
cyclohexane carboxylic acid or perfluorocyclohexanecarboxylic
acid using EDAC and DMAP in dichloromethane gave the target
compounds 6a–c and 7a–c respectively.
2854, 2924 cmꢁ1
.
2.2.2 (S)-4-(1-Methylheptyloxycarbonyl)phenyl 40-[11-(cyclo-
hexylcarbonyloxy)undecyloxy biphenyl-4-carboxylate (6b).
Compound 5b (250 mg; 0.41 mmol), cyclohexanecarboxylic acid
(55 mg; 0.43 mmol), EDAC (78 mg; 0.41 mmol), DMAP (10 mg),
1
and dichloromethane (30 ml). Yield 200 mg (69%). H NMR
(CDCl3) d: 0.88 (3H, t), 1.20–1.52 (31H, m), 1.57–1.67 (3H, m),
1.70–1.94 (7H, m), 2.28 (1H, tt), 4.01 (2H, t), 4.05 (2H, t), 5.16
(1H, sext), 7.01 (2H, d), 7.31 (2H, d), 7.59 (2H, d), 7.70 (2H, d),
8.12 (2H, d), 8.23 (2H, d) ppm; 13C NMR (CDCl3) d: 14.06
(CH3), 20.08 (CH-CH3), 22.57 (CH2-CH3), 25.39 (CH2-
CH2CH3), 25.45 (2 ꢀ cyclohexyl CH2), 25.76 (CH2), 25.90
(CH2), 26.02 (CH2), 28.63 (1 ꢀ cyclohexyl CH2), 29.04 (2 ꢀ
cyclohexyl CH2), 29.15 (CH2), 29.21 (CH2), 29.37 (CH2), 29.47 (3
ꢀ CH2), 29.53 (CH2), 31.72 (CH2), 36.05 (CH2CH2-CH), 43.26
(cyclohexyl CH), 64.23 (CH2O), 68.13 (CH2O), 71.93 (O-CH
(CH3)CH2), 114.98 (2 ꢀ Ar-CH), 121.69 (2 ꢀ Ar-CH), 126.63 (2
ꢀ Ar-CH), 127.02 (Ar-C), 128.39 (2 ꢀ Ar-CH), 128.50 (Ar-C),
130.77 (2 ꢀ Ar-CH), 131.13 (2 ꢀ Ar-CH), 131.84 (Ar-C), 146.19
(Ar-C), 154.52 (Ar-C), 159.58 (Ar-C), 164.64 (C]O), 165.53
(C]O), 176.24 (C]O) ppm; IR (neat) nmax: 764, 825, 887, 1064,
2.1 General methods
Cyclohexanecarboxylic acid, perfluorocyclohexanecarboxylic
acid, EDAC, and DMAP were purchased from Aldrich. General
solvents were used as received from commercial suppliers; all of
these materials were used without further refinement. Purifica-
tion of the intermediates and final products was achieved using
column chromatography over C60, 230–400 mesh silica gel as the
stationary phase (Merck).
The structures of the products were analysed using a range of
1
spectral techniques including H and 13C spectrometry (JEOL
DELTA 400 MHz spectrometer), where the spectra, unless
otherwise stated, were recorded in CDCl3; infra-red spectrometry
(Shimadzu IR Prestige-21 FT-IR Spectrophotometer, fitted with
a Specac Golden Gate ATR crystal adaptor).
1165, 1188, 1265, 1465, 1504, 1604, 1710, 1728, 2854, 2924 cmꢁ1
.
2.2.3 4-(1-Methylheptyloxycarbonyl)phenyl
hexylcarbonyloxy)undecyloxy biphenyl-4-carboxylate
40-[11-(cyclo-
(6c).
Compound 5c (300 mg; 0.49 mmol), cyclohexanecarboxylic acid
(60 mg; 0.49 mmol), EDAC (90 mg; 0.49 mmol), DMAP (10 mg)
and dichloromethane (30 ml). Yield 0.16 g (45%). 1H NMR
(CDCl3) d: 0.87 (3H, t), 1.20–1.51 (31H, m), 1.57–1.67 (3H, m),
1.70–1.90 (7H, m), 2.28 (1H, tt), 4.01 (2H, t), 4.04 (2H, t), 5.16
(1H, sext), 7.00 (2H, d), 7.29 (2H, d), 7.59 (2H, d), 7.69 (2H, d),
8.12 (2H, d), 8.23 (2H, d) ppm; 13C NMR (CDCl3) d: 14.06
(CH3), 20.08 (CH-CH3), 22.57 (CH2-CH3), 25.39 (CH2-
CH2CH3), 25.44 (2 ꢀ cyclohexyl CH2), 25.76 (CH2), 25.89
(CH2), 26.02 (CH2), 28.64 (1 ꢀ cyclohexyl CH2), 29.03 (2 ꢀ
cyclohexyl CH2), 29.14 (CH2), 29.21 (CH2), 29.37 (CH2), 29.47 (3
ꢀ CH2), 29.53 (CH2), 31.72 (CH2), 36.05 (CH2CH2-CH), 43.26
(cyclohexyl CH), 64.22 (CH2O), 68.13 (CH2O), 71.93 (O-CH
(CH3)CH2), 114.97 (2 ꢀ Ar-CH), 121.69 (2 ꢀ Ar-CH), 126.62 (2
ꢀ Ar-CH), 127.01 (Ar-C), 128.38 (2 ꢀ Ar-CH), 128.50 (Ar-C),
130.77 (2 ꢀ Ar-CH), 131.12 (2 ꢀ Ar-CH), 131.81 (Ar-C), 146.19
(Ar-C), 154.51 (Ar-C), 159.56 (Ar-C), 164.60 (C]O), 165.49
(C]O), 176.19 (C]O) ppm; IR (neat) nmax: 763, 833, 887, 1018,
1072, 1165, 1195, 1257, 1465, 1497, 1597, 1710, 1728, 2854,
2.2 Synthetic procedures
The preparation of the mesogens 5a–c has been reported previ-
ously8 and for the sake of brevity their synthesis will not be
discussed in this article. The preparation of compounds 6a–c and
7a–c utilises the same methodology (see Scheme 1) and the
preparation of 6a is given as a representative example.
2.2.1 (R)-4-(1-Methylheptyloxycarbonyl)phenyl 40-[11-(cyclo-
hexylcarbonyloxy)undecyloxy
biphenyl-4-carboxylate
(6a).
Compound 5a (150 mg; 0.24 mmol), cyclohexanecarboxylic acid
(31 mg; 0.24 mmol), EDAC (47 mg; 0.24 mmol) and DMAP (10
mg) were stirred together at room temperature in dichloro-
methane (30 ml) for 18 hours. Upon completion, the solvent was
removed in vacuo and the product purified by column chroma-
tography over silica (dichloromethane as eluent). The product
was recrystallised from acetonitrile to give a white powder. Yield
130 mg (73%). 1H NMR (CDCl3) d: 0.88 (3H, t), 1.20–1.50 (31H,
m), 1.57–1.67 (3H, m), 1.70–1.94 (7H, m), 2.28 (1H, tt), 4.01 (2H,
t), 4.04 (2H, t), 5.16 (1H, sext), 7.00 (2H, d), 7.30 (2H, d), 7.59
2924 cmꢁ1
.
9032 | J. Mater. Chem., 2011, 21, 9031–9042
This journal is ª The Royal Society of Chemistry 2011