Pleochroic azo dyes, a liquid crystal composition containing the azo

Abstract

Pleochroic azo dyes represented by the formula (I): ##STR1## wherein X represents group --OCOR.sup.1 or --COOR.sup.1 (wherein R.sup.1 represents an alkyl group, an alkoxyalkyl group, an alkoxyphenyl group, an alkylcyclohexyl group, an alkoxyalkylcyclohexyl group, a cycloalkylcyclohexyl group, an alkoxycyclohexyl group, or a phenyl group substituted by a substituent selected from among an alkyl group containing 3 to 18 carbon atoms, an alkoxyalkyl group, a cycloalkyl group, an aryl group, a cyano group, a halogen atom, an acyloxy group, a carboxylic acid ester group, and an arylazo group); Y represents a hydrogen atom, an alkyl group, an alkoxyalkyl group, a cycloalkyl group, an alkoxy group, a nitro group, a cyano group, a carboxylic acid ester group, an acyloxy group, an alkylsulfonyl group, an aryl group, a halogen atom, or group ##STR2## wherein R.sup.2 and R.sup.3 each represents a hydrogen atom, an alkyl group, an alkoxyalkyl group, or R.sup.2 and R.sup.3 may be connected to each other to form a nitrogen-containing ring together with the adjacent nitrogen atom; Z.sup.1 to Z.sup.9 each represents a hydrogen atom, a halogen atom, a methyl group, a hydroxy group, a methoxy group or a cyano group, or Z.sup.1, Z.sup.2 and Z.sup.3 may be connected to R.sup.2 or R.sup.3 to form a nitrogen-containing ring, or Z.sup.1 and Z.sup.2, and Z.sup.4 and Z.sup.5, or Z.sup.7 and Z.sup.8 may be connected to each other to form an aromatic ring; at least one of ##STR3## and n represents 0, 1 or 2, a liquid crystal composition containing the pleochroic azo dyes and a display device using the liquid crystal composition.