The Secretary of State for Defence in Her Britannic Majesty's Government

Richard M Scroston

George W Gray

Kenneth J Toyne

David Lacey

David Holmes

Compounds suitable for use as constituents of ferroelectric smectic liquid crystal compositions, which are ester of formula (I), where R.sub.2 and R.sub.3 together represent the residue of an alicyclic hydrocarbon ring system where *C is an asymmetric carbon atom and X is a chain of up to three linked aromatic or alicyclic six-membered organic cyclic groups, laterally and/or terminally substituted. Preferred compounds have a formula (II), where R.sub.1 is alkyl or alkoxy, A, B, and D are phenyl, fluoro or chloro substituted phenyl or cyclohexyl, n is 0 or 1, Y is a bond or CH.sub.2 CH.sub.2 if n is 0, or a bond CH.sub.2 CH.sub.2 COO or COO if n is 1. Preferred groups C(CN)R.sub.2 R.sub.3 are formula (III) and (IV). ##STR1##

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Richard M Scroston