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

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Stc, Inc

Daniel J Young

David Coates

George W Gray

Kenneth J Toyne

David Lacey

Lawrence Kam Chan

Peter A Gemmell

Matthew F Bone

Adam Jackson

Richard M Scrowston

Compounds which may be used as a dopant or host in a ferroelectric chiral smectic liquid crystal mixture. The compounds are characterized in that they are derivates of an X-hydroxy carboxylic acid and contain the chiral unit (I), in which Ro may be alkyl, alkoxy, halogen, formula (II), where b may be 0 to 3 and the phenyl ring may be substituted, and a is 0 or 1. The chiral unit is combined with a range of mesogenic combinations of groups. Lactic acid derivatives are described in detail (i.e. Ro.dbd.methyl) together with various preparative routes, for example the compound formula (III), which has dopant properties in a range of hosts.

Alpha-hydroxy carboxylic acid derivates suitable for use in liquid

19 -hydroxy carboxylic acid derivatives suitable for use in liquid

##STR1## Ferroelectric smectic liquid crystal mixtures are provided consisting of two constituents; a smectic host and another containing a chiral compound in which rotation of the chiral center relative to the molecular core is sterically hindered, so that the chiral compound induces a high Ps in the mixture. A preferred class of chiral compounds is those derived from naturally occurring compounds with chiral groups, especially .alpha.-hydroxycarboxylic acids, amino acids and terpenoids, e.g. with chiral groups (I), (II), (III). The chiral group is incorporated into a compound containing a mesogenic combination of groups, e.g. with chains of cyclic groups and some mesogenic combinations are described.

Compounds for ferroelectric liquid crystal devices

Terpenoid derivatives and liquid crystal materials and devices

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Doncaster, United Kingdom

Daniel J Young