4-cyanophenyl-4-heptylbenzoate

NMR studies it has been observed that the long molecular axis is nearly parallel to the para- x s of the phenyl moiety and hence the first few fragments of the chain attached to the indazole group are not along this axis. This requires that the alkoxy chain attached to the indazole group has at least six carbon atoms to promote liquid crystalline behaviour. The order parameters of 4 -cyanophenyl 4-heptylbenzoate have been obtained by using 2D-NMR spectroscopy.Linear relationships between C-chemical shifts and order parameters have been obtained. Phase behaviour of a mixture of this liquid crystal and its chain-perfluorinated analogue has also been studied. 

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Miscibility studies of the nematic dye-containing copolymers with suitable low molecular weight liquid crystals yield homogeneous nematic mixtures. A binary mixture of 4-cyanophenyl-4-heptylbenzoate and 4-cyanophenyl-4-pentylbenzoate is miscible with the phenylbenzoate-anthraquinone copolymers. 

Lokanath, N.K., D. Revannasiddaiah, M.A. Sridhar, J.S. Prasad, and D.K. Gowda. 1997. Crystal structure of 4 -cyanophenyl-4-heptylbenzoate. Zeitschrift filr Kristallographic 212 385-386. 

Distinct subsections of the molecules comprising liquid crystals have also been observed using the rate of MQC development in a mixture of liquid crystalline materials. Separate MQ signals were observed for effectively isolated spin systems (phenyl rings) and weakly coupled multi-spin clusters (alkyl tails)80 in a mixture of 4-cyanophenyl 4 -butylbenzoate and 4 cyano-phenyl 4 -heptylbenzoate. 

FIGURE 2.21 Unit cells of the 4 -cyanophenyl-4-n-pentylbenzoate, 4 -cyanophenyl-4-n-heptylbenzoate [128,129], and orientation director n, coinciding with the main c axis. 

The presence of more than one molecule in the unit cell oriented in a different way leads to splitting of the IR band according the Bethe theory and the submaxima possess different polarization. In these cases the eUmination is obtained to an inflex point as shown in Figure 2.26, where the consequent elimination of the submaxima at 1738 cm- in 4 -cyanophenyl-4-n-heptylbenzoate is obtained. 

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