95379-31-0Relevant academic research and scientific papers
The Effect of Lateral Fluorosubstitution on the Liquid Crystalline Properties of some 4-n-Alkyl-, 4-n-Alkoxy- and Related 4-Substituted-4'-cyanobiphenyls
Fearon, J. E.,Gray, G. W.,Ifill, A. D.,Toyne, K. J.
, p. 89 - 104 (2007/10/02)
The syntheses of several 4-n-alkyl-, 4--, 4-- and 4-n-alkoxy-4'-cyano-2'-fluorobiphenyls and -4'-cyano-2-fluorobiphenyls are presented and the transition temperatures for these compounds are reported and discussed.In the alkylkcyanobiphenyls, a 2-fluoro-substituent causes a greater depression of TN-I (35-39 deg C) than a 2'-fluoro-substituent (13-18 deg C) and a similar situation arises for the cyclohexylethyl compounds.The fluoro-substituted alkoxy-compounds also give two series with depressions of TN-I of 34-41 deg C for the 2-fluoro- and 15-20 deg C for the 2'-fluoro-compounds.In non-cyano systems, 2- and 2'-fluoro-substituents in biphenyl derivatives give similar depressions in TN-I, which are larger than found in cyano systems, and the different depressions for the fluoro-substituted cyano compounds are thought to arise because of the effect of the fluorine on the anti-parallel correlations of the parent systems.The effects on smectic and nematic thermal stabilities are qualitatively similar, but are usually greater for smectic transitions.A comparison is made between 4-trans-cyclohexylethyl and 4-phenylethyl units in the 4'-cyano- and 4'-bromo-2'-fluorobiphenyls.
