Liquid crystal compositions

Claim 1

A liquid crystal composition comprising, in combination with a host liquid crystal material, at least one guest indigo dye of the following general formula ##STR24## in which A and B independently represent S or N-Y in which Y represents an alkyl group having from 1 to 3 carbon atoms, an acyl group having from 2 to 4 carbon atoms or a hydrogen atom, R 2 represents an alkyl group having from 4 to 10 carbon atoms and branched at the alpha carbon, R 6 represents a hydrogen atom, a branched or linear alkyl group, a 4-substituted phenyl group, a 4-substituted cyclohexyl group or a 4-substituted phenyloxy group, R 1 , R 3 , R 4 , R 5 , R 7 and R 8 independently represent a hydrogen atom, a halogen atom, an alkyl group having from 1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon atoms, a nitro group, an amino group, or --NR 9 R 10 , in which R 9 represents an alkyl group having from 1 to 3 carbon atoms and R 10 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms.