Composition based on liquid crystal for electro-optical device

Abstract

A composition for use in an electro-optical device, particularly a display device, contains anthraquinone pleochroic dye of formula (I): ##STR1## where R.sub.1 is a substituted or unsubstituted amino group or a hydroxy group; R.sub.2 is a hydrogen, a substituted or unsubstituted amino, a hydroxy or a cyano group; each of R.sub.3 and R.sub.4, which are identical or different, is a hydrogen atom, a substituted or unsubstituted amino group, a hydroxy, a nitro or a cyano group; R is a hydrogen or halogen atom or a hydroxy, lower alkyl or lower alkoxy group; n is 1, 2, 3 or 4, the Rs being identical or different when n is 2, 3 or 4; and X is a hydrogen or halogen atom, a hydroxy or mercapto group, a straight, branched or cyclic C.sub.1-16 alkyl radical, a substituted or unsubstituted aryl group or a group of formula OR', OAr, SR', SAr, COOR', COOAr, COO--C.sub.6 H.sub.4 --R', OOCR', OOCAr, OOC--C.sub.6 H.sub.4 --R', CONHR', CONHAr, NHR', NHAr, NHCOR', NHCOAr, OCOOR', OCOOAr, CH.dbd.N--C.sub.6 H.sub.4 --R', N.dbd.CH--C.sub.6 H.sub.4 --R', N.dbd.N--C.sub.6 H.sub.4 --R' or ##STR2## where R' is a hydrogen atom or a straight, branched or cyclic C.sub.1-10 alkyl residue. Compounds of formula (I) have a high order parameter and are very stable.

Dependencies are inferred from the claim text.