Ferroelectric Liquid Crystals. Part 9. Laterally substituted phenyl benzoates incorporating a trans‐1,4‐disubstituted cyclohexane ring

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Abstract
About 65 diverse phenyl benzoates incorporating a trans‐1,4‐disubstituted cyclohexane ring and at least one lateral substituent have been synthesised. The dependence of the liquid‐crystal transition temperatures of these materials on various lateral substituents (F, Cl, CN, and Br) in different positions of the esters has been investigated systematically. The influence of up to four F‐atoms in various positions of a standard ester has been thoroughly studied and the optimum combination for a broad smectic C mesomorphic range established. In consequence, three homologous series incorporating the 4‐alkoxy‐2,3‐difluorobenzoic‐acid moiety were prepared. An additional CC bond was introduced into the alkyl chain attached to the cyclohexane ring of some of these esters and the resulting modifications of the transition temperatures determined. Three ester series incorporating a lateral substituent and the optically active (+)‐(S)‐(1‐methylheptyl)oxy substituent have also been synthesised, and similar effects have been observed. These materials can be used as important components of commercial chiral smectic C mixtures for electro‐optic display device applications.