The Liquid Crystal Properties of Some Cyano-Substituted Aryl Esters

Abstract

Forty-five aryl esters (R-Ar-CO.O-Ar′-CN) containing terminal cyano and R = alkyl or alkoxy substituents were prepared. The aryl moieties of the esters were either 1,4-phenylene, 2,6-naphthylene or 4,4′-biphenylene. All combinations of these aryl groups were examined and the liquid crystal properties are compared with one another and with those for analogous phenyl benzoate esters. All the compounds were nematogenic, and it was found possible to predict the effect of a naphthylene or biphenylene group, relative to a phenylene group, on the nematicisotropic liquid (N-I) value. This information was used to predict the properties of other esters. Some side-substituted esters of the same kind were also examined, and depressions in melting point and in N-I values compared with the unsubstituted compounds were found. The effects of each aromatic moiety on the dielectric permittivities were determined and the results are compared for the various esters.