Patent ID: 7220857

Claim:
A compound represented by formula (III): wherein V 1 and V 2 each represent a substituent; the substituents V 1 and V 2 each represent a substituent represented by W 1 or W 2 described below; when at least one V 1 is a substituent represented by W 1 , V 2 is a substituent represented by W 2 , or when at least one V 1 is a substituent represented by W 2 , V 2 is a substituent represented by W 1 ; r represents 1 to 4; M 1 represents a counter ion; m 1 represents the number necessary for neutralizing charge; W 1 represents a hydroxyl group, a primary, secondary or tertiary amino group, an acylamino group, or a sulfonamido group; W 2 represents a nitro group, a cyano group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkyl- or aryl-sulfonyl group, a carbamoyl group, a sulfamoyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a sulfo group, a carboxyl group, a heterocyclic oxy group, an ammonio group, an alkyl- or aryl-sulfinyl group, an alkyl- or aryl-sulfonyl group, an acyl group, or an aryl- or heterocyclic-azo group; and the compound represented by formula (III) optionally has a substituent other than those represented by V 1 and V 2 .