Patent ID: 7396399

Claim:
An ink composition comprising an aqueous medium and a bipyridine-based metal complex represented by formula (I): R 1 , R 2 , and R 3 are respectively mono-substituents, or the same or different multi-substituents, and are selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, —SO 3 H, —COOH, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 1 -C 20 heteroalkyl group, a hydroxy group, an amino group, a cyano group, a substituted or unsubstituted C 2 -C 20 alkenyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, a substituted or unsubstituted C 1 -C 20 alkylsulfonamide group, a substituted or unsubstituted C 6 -C 20 arylsulfonamide group, a substituted or unsubstituted C 1 -C 20 acylamino group, a C 1 -C 20 alkylureido group, a C 6 -C 20 arylureido group, a C 2 -C 20 alkoxycarbonyl group, a C 2 -C 20 alkoxycarbonylamino group, a carbamoyl group, a sulfamoyl group, a sulfo group or its salt, a carboxy group or its salt, a substituted or unsubstituted C 1 -C 20 hydroxyalkyloxyalkyl group, a substituted or unsubstituted C 1 -C 20 dialkylaminoalkyl group, a substituted or unsubstituted C 6 -C 20 pyridylalkyl group, a substituted or unsubstituted C 5 -C 20 pyridyl group, a substituted or unsubstituted C 6 -C 20 imidazolyl group, a hydrazine group, a hydrozone group, a substituted or unsubstituted C 1 -C 20 pyridylalkyl group, a substituted or unsubstituted C 6 -C 20 aryl group, a substituted or unsubstituted C 6 -C 20 arylalkyl group, a substituted or unsubstituted C 6 -C 20 heteroaryl group, or C 6 -C 20 heteroarylalkyl group, a substituted or unsubstituted C 6 -C 20 heteroarylalkenyl group, and a substituted or unsubstituted C 3 -C 20 heterocycloalkyl group, wherein not all of R 1 , R 2 and R 3 are a hydrogen atom; M is a metal atom of one of groups III to XIV; and Z is a counter ion.