THE SYNTHESIS AND LIQUID-CRYSTAL PROPERTIES OF SOME 4-N-NONYLPHENYL ESTERS OF 3-(4'-N-ALKOXYBIPHENYLYL)-3-METHYL-PROPANOIC AND 3-(4'-N-ALKOXYBIPHENYLYL)-3-METHYL-PROPANOIC ACIDS AND THEIR LATERALLY FLUORINATED ANALOGS

A number of 4-n-nonylphenyl esters and mono- and di-fluorinated 4-n-nonylphenyl esters derived from 3-(4'-n-alkoxybiphenylyl)propanoic acids (II) have been synthesized and their thermotropic liquid crystal properties assessed with a view to obtaining tilted smectic phases for possible use in ferroelectric display devices. Many of these compounds exhibit wide temperature range S(C) and S(I/F) phases, but none gave the ideal phase sequence S(C)-S(A)-N-I mainly because the structure of these compounds was not conducive to the formation of the nematic phase. To try to alleviate this problem a series of 4-n-nonylphenyl esters based on 3-(4'-n-alkoxybiphenylyl)-3-methylpropanoic acid was prepared, where a lateral methyl group was incorporated in the beta-position of the -CH2CH2CO2- linkage. Incorporation of the lateral methyl group encouraged the formation of a nematic phase at the expense of both the smectic A phase and tilted smectic phases.