Abstract: The present liquid crystal composition is characterized by containing a dye of anthraquinone series represented by the following general formula (1) dissolved as a guest in a host liquid crystal: ##STR1## wherein R represents an alkyl group or a cycloalkyl group. The alkyl group or the cycloalkyl group of the dye of anthraquinone series includes those substituted by alkyl, hydroxyl, alkoxy, cycloalkyl, aryl, aryloxy, dialkylamino, or heterocyclic residue. Furthermore, the liquid crystal composition can contain two or more other kinds of the dye of anthraquinone series, or can be used in combination with other dyes. In the dye of anthraquinone series, the group --COOR at the 2-position and the group --CN at the 3-position are particularly important for realization of cyan color and a high S value.The dye of anthraquinone series is particularly effective for preparation of a black dye.

Abstract: Phthalonitrile derivatives represented by the formula (I): ##STR1## (wherein X and Y each represents an alkyl group having 1 to 9 carbon atoms, an alkoxy group havng 1 to 9 carbon atoms, ##STR2## (wherein R.sup.1 represents a hydrogen atom, --C.sub.m H.sub.2m+1, --O--(CH.sub.2 CH.sub.2 O).sub.n --C.sub.m H.sub.2m+1, ##STR3## or a halogen atom, wherein m represents an integer of 1 to 9 and n represents 0, 1 or 2), but at least one of X and Y does not represent a methyl group, and Y does not not represent an alkyl group having 1 to 9 carbon atoms or an alkoxy group having 1 to 9 carbon atoms in the case that X represents R.sup.1 H and R.sup.1 represents an alkyl group having 1 to 9 carbon atoms).

Abstract: A liquid crystal composition comprising a host liquid crystal and at least one perylene dye dissolved therein represented by the formula: ##STR1## wherein X represents an oxygen atom or a sulfur atom, R.sup.1 and R.sup.2 each represents an aryl group when X represents an oxygen atom; or an aryl group or an alkyl group containing 1 to 18 carbon atoms when X represents a sulfur atom.

Abstract: A dye laser comprising a container retaining a dye solution for laser and an energy source for pumping connected to the container, the dye solution containing a pyrazoloazaxanthenoisoquinolinone dye.

Abstract: A liquid crystal composition comprising a host liquid crystal And a pleochroic dye dissolved therein as a guest material is described, which is characterized in that the pleochroic dye contains an anthraquinone-based dye yielding a Magenta color and/or an orange color.

Abstract: A liquid crystal composition containing at least one quinophthalone series dye represented by the formula ##STR1## wherein: X represents hydrogen, a chlorine atom or a bromine atom; and R represents --OR.sup.1 or --SR.sup.1, wherein R.sup.1 represents an alkyl group, a cycloalkyl group, an alkoxyalkyl group, a phenyl group, a p-hydroxyphenyl group, a p-cycloalkylphenyl group, a p-alkylphenyl group, a p-alkoxyphenyl group or an aralkyl group; ##STR2## wherein R.sup.2 and R.sup.3 each represents hydrogen, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, a cycloalkyl group, a phenyl group, a p-alkylphenyl group, a p-hydroxyphenyl group, a p-alkoxyphenyl group or an aralkyl group; or a saturated heterocyclic ring.

Abstract: An azo dye having the formula (1): ##STR1## wherein R.sup.1 represents hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, hydroxyalkyl, alkoxyalkyl, alkoxycarbonylalkyl, acyloxyalkyl, acylalkyl, hydroxyalkylaminoalkyl, cyanoalkyl, aminoalkyl, N,N-dialkylaminoalkyl, alkylaminoalkyl, chloroalkyl, bromoalkyl, carboxyalkyl, morpholinoalkyl, cyclohexyl, phenethyl, benzyl, phenyl, chlorophenyl, methoxyphenyl, nitrophenyl, tolyl, xylyl, dialkylaminophenyl and alkyl containing an ammonium group wherein the ammonium nitrogen is quaternized by alkyl groups or by an amino group with alkyl groups, or wherein the ammonium nitrogen atom is the heterocyclic nitrogen atom of a morpholine ring or a pyridine ring, wherein R.sup.2, R.sup.3, R.sup.4 and R.sup.5 represent hydrogen, chlorine, bromine, nitro, cyano, carboxyl, methyl, ethyl, propyl, butyl, trifluoromethyl, .beta.