Ebauches S.a.

Asulab S.a.

Trung H Phan

Jacques Cognard

Jurgen Markert

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.

Composition based on liquid crystal for electro-optical device

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; each of R.sub.2, R.sub.3 and R.sub.4, which are identical or different, is a hydrogen atom, a substituted or unsubstituted amino group, a hydroxy group or a nitro 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; 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 ##STR2## where R' is a hydrogen atom or a straight, branched or cyclic C.sub.1-10 alkyl residue, and Y is a hydrogen atom or a side chain of the formula: ##STR3## where X', R' and n' have the same definitions as and are respectively identical to or different from X, R and n, the side chain being in position 6 when the compound is substituted in position 2 and in position 7 when it is substituted in position 3. Compounds of formula (I) have a high order parameter and are very stable.

The liquid crystal-base composition for an electro-optical device contains an anthraquinone pleochroic coloring agent of formula (I) as defined in claim 1, that is to say, with in particular at least one hydroxy or amino group in position 1 and a heterocyclic side chain which is directly substituted in position 2, or 2 and 6, or 3, or 3 and 7. The compounds (I) have a high order parameter and are stable, thereby imparting to the compositions the properties required for use thereof for example in a display device. ##STR1##

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Trung H Phan