film camera (Huber Diffraktionstechnik GmbH) or small
angle equipment. The samples were filled in glass capillaries (id
1 mm), the temperature was controlled better than ¡1 K. X-
Ray measurements on oriented samples were carried out with a
2D detector (HI-Star, Siemens AG). The alignment of the
samples was achieved by annealing a drop of the liquid crystal
on a glass plate immediately below the clearing temperature. In
the case of compound C6O the homogeneous orientation was
obtained in the nematic state by applying a magnetic field
(0.7 T). Electro-optical measurements were made using the
usual experimental set-up described in an earlier paper.5 The
spontaneous polarization was measured with the triangular
wave voltage method using the same set-up.
NMR measurements were performed with a Bruker MSL
500 spectrometer at a magnetic field of 11.7 T. The samples
were put in standard 5 mm tubes. The proton decoupled 13C
spectra at 125 MHz, without spinning, are well resolved in the
isotropic liquid. We used pulse and CP excitation for 13C
resonance and observed the spectra using continuous and
pulsed decoupling (Waltz). In the case of continuous irradia-
tion the decoupling efficiency in the different regions of the
spectra depends on the proton frequency offset.
C8O (R~C8H17O). 1H NMR (400 MHz, CDCl3) d: 0.87 (t,
3J~6.8 Hz, 6H, CH3), 1.28–1.49 (m, 20H, CH2), 1.75–1.82 (m,
4H, OCH2CH2), 3.97 (t, 3J~6.5 Hz, 4H, OCH2), 6.93 (dd,
3J~9.0 Hz, 4J~2.7 Hz, 4H, Ar), 7.28 (dd, 3J~8.8 Hz,
4J~1.6 Hz, 4H, Ar), 7.33 (dd, 3J~8.5 Hz, 4J~2.2 Hz, 1H,
Ar), 7.56 (d, 4J~2.2 Hz, 1H, Ar), 7.80 (d, 3J~8.4 Hz, 1H, Ar),
8.03 (d, 3J~8.4 Hz, 4H, Ar), 8.25 (d, 3J~8,4 Hz, 2H, Ar), 8.32
(d, 3J~8.4 Hz, 2H, Ar), 8.57 (s, 2H, CHLN). Elemental
analysis for C51H55N3O6 (805.95): calcd: C 76.00, H 6.88, N
5.21; found: C 75.76, H 6.57, N 4.83. IR (KBr) nCN 2227cm21
.
MS m/z (rel intensity): 806 (10), 805 (47), 556 (18), 470 (15),
336(100), 241 (42), 224 (43), 195 (41), 69 (21).
C12 (R~C12H25). 1H NMR (200 MHz CDCl3) d: 0.88 (t,
3J~6.2 Hz, CH3), 1.27–1.51 (m, 36H, CH2), 1.62–1.78 (m, 4H,
3
Ar-CH2CH2), 2.64 (t, J~7.6 Hz, 4H, Ar-CH2), 7.26 (s, 8H,
Ar), 7.36 (dd, 3J~8.7 Hz, 4J~2.2 Hz, 1H, Ar), 7.59 (d,
4J~2.0 Hz, 1H, Ar), 7.82 (d, 3J~8.8 Hz, 1H, Ar), 8.07 (d,
3J~7.4 Hz; 4J~1.6 Hz, 4H, Ar), 8.27–8.37 (m, 4H, Ar), 8.59 (s,
2H, CHLN).
C14 (R~C14H29). 1H NMR (200 MHz CDCl3) d: 0,88 (t,
3J~6.3 Hz, 6H, CH3), 1.27–1.52 (m, 44H, CH2), 1.59–1.72 (m,
The director orientation of the samples in the smectic A and
C phases are perfect, giving sharp spectral lines. In the nematic
phase the line widths are greater.
3
4H, Ar-CH2CH2), 2.64 (t, J~7.6 Hz, 4H, Ar-CH2), 7.25 (s,
8H, Ar), 7.36 (dd, 3J~8.6 Hz, 4J~2.2 Hz, 1H, Ar), 7.59 (d,
4J~2.2 Hz, 1H, Ar), 7.83 (d, 3J~8.7 Hz, 1H, Ar), 8.07 (dd,
3J~6.6 Hz; 4J~1.6 Hz, 4H, Ar), 8.26–8.37 (m, 4H, Ar), 8.59 (s,
2H, CHLN).
Synthetic procedure
The structure of the products was proved by 1H NMR
spectroscopy (Varian Gemini 200 and Varian Unity 400), mass
spectroscopy (Intectra GmbH, AMD 402, electron impact,
70 eV); Finnigan MAT LCQ Spectrometer and IR spectro-
meter Bruker IFS 66. Elemental analysis were performed using
a CHNS-932 (Leco Co.) elemental analyser.
C6O (R~C6H13O). 1H NMR (200 MHz CDCl3) d: 0.90 (t,
3J~6.5 Hz, 6H, CH3), 1.23–1.50 (m, 12H, CH2), 1.72–1.82 (m,
4H, OCH2CH2), 3.98 (t, 3J~6.6 Hz, 4H, OCH2), 6.93 (d,
3J~8.8 Hz, 4H, Ar), 7.28 (d, 3J~8.8 Hz, 4H, Ar), 7.35 (dd,
3J~8.6 Hz, 4J~2.1 Hz, 1H, Ar), 7.56 (d, 4J~2.0 Hz, 1H, Ar),
7.80 (d, 3J~8.6 Hz, 1H, Ar), 8.03 (d, 3J~8.5 Hz, 4H, Ar),
8.23–8.34 (m, 4H, Ar), 8.57 (s, 2H, CHLN).
2,4-Dihydroxybenzonitrile. A solution of 2,4-dihydroxyben-
zaldehyde (22.5 g, 0.16 mol) in 60 ml of ethanol was treated
with a concentrated aqueous solution of hydroxylamine
hydrochloride (16.7 g, 0.24 mol) followed by slow addition of
a concentrated aqueous solution of Na2CO3?10H2O (22.9 g,
0.08 mol). Crystals were obtained and isolated by filtration.
Recrystallisation from water gives 22.3 g (91%) of the 2,4-
dihydroxybenzaldoxime. Mp 190–192 ‡C (ref. 8 191 ‡C). The
solid was then dissolved and refluxed in 90 ml of acetic
anhydride for 3 h. The solvent was removed in vacuo. The
product was recrystallized from ethanol to give 14 g (44%) of
the acetylated intermediate. This product (0.064 mol) was
treated with aqueous KOH solution (12 g of KOH in 55 ml of
water), and the resulting solution was stirred for 3 days at
ambient temperature. Careful acidification (pH 2) with dilute
sulfuric acid (20 vol%) was followed by extraction with ethyl
acetate (3650 ml). The pooled organic phases were dried over
Na2SO4, and the solvent was removed in vacuo. The product
was purified by column chromatography on silica gel using
ethyl acetate–heptane (20 : 1) as eluent. Yield 7 g (82%). Mp
174–175.5 ‡C (Mp 175 ‡C8). 1H NMR (200 MHz DMSO-d6) d:
10.03 (s, 2H, OH), 6.56–6.50 (m, 3H, Ar). IR (Nujol)
C9O (R~C9H19O). 1H NMR (400 MHz CDCl3) d: 0.87 (t,
3J~6.8 Hz, 6H, CH3), 1.28–1.49 (m, 12H, CH2), 1.71–1.82 (m,
4H, OCH2CH2), 3.97 (t, 3J~6.6 Hz, 4H, OCH2), 6.93 (d,
3J~8.9 Hz, 4J~2.7 Hz, 4H, Ar), 7.28 (d, 3J~8.9 Hz, 4H, Ar),
7.33 (dd, 3J~8.6 Hz, 4J~2.1 Hz, 1H, Ar), 7.56 (d, 4J~2.1 Hz,
1H, Ar), 7.80 (d, 3J~8.6 Hz, 1H, Ar), 8.03 (dd, 3J~8.4 Hz,
4J~2.0 Hz, 4H, Ar), 8.24–8.33 (m, 4H, Ar), 8.57 (s, 2H,
CHLN).
C12O (R~C12H25O). 1H NMR (200 MHz CDCl3) d: 0.86 (t,
3J~6.4 Hz, 6H,CH3), 1.25–1.44 (m, 20H, CH2), 1.72–1.82 (m,
4H, OCH2CH2), 3.97 (t, 3J~6.6 Hz, 4H, OCH2), 6.93 (d,
3J~8.8 Hz, 4H, Ar), 7.28 (d, 3J~8.8 Hz, 4H, Ar), 7.34 (dd,
3J~8.8 Hz, 4J~2.2 Hz, 1H, Ar), 7.56 (d, 4J~2.2 Hz, 1H, Ar),
7.80 (d, 3J~8.6 Hz, 1H, Ar), 8.03 (dd, 3J~8.3 Hz, 4J~2.0 Hz,
4H, Ar), 8.23–8.34 (m, 4H, Ar), 8.57 (s, 2H, CHLN).
Acknowledgements
This work was supported by the Deutsche Forschungsge-
meinschaft (DFG) and the Fonds der Chemischen Industrie.
n
CN~2230 cm21
.
References
4-Cyano-1,3-phenylene bis[4-(4-n-alkyl- or -alkoxy-phenyli-
minomethyl)benzoates] C12, C14, C6O, C8O, C9O, C12O. The
mixture of 0.18 g (1.3 mmol) of 2,4-dihydroxybenzonitrile,
2.6 mmol of the corresponding 4-(4-alkyl- or -alkoxy-phenyl-
iminomethyl)benzoic acid,10 0.56 g (2.7 mmol) DCC, and
DMAP as catalyst in 40 ml of dichloromethane was stirred
at room temperature for 24 h. The precipitate was filtered out,
the solvent was evaporated. The products were recrystallised
from DMF–ethanol.
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