HEPTAMETHINECYANINE COMPOUND, NEAR-INFRARED ABSORBING INK, HEAR-INFRARED ABSORBING SHEET AND SILVER HALIDE PHOTOGRAPHIC MATERIAL

摘要

PROBLEM TO BE SOLVED: To obtain a dye which scarcely has any absorptions in the visible region, an ink containing the same and a photographic material containing the same by using a near-infrared absorbing dye comprising a heptamethinecyanine compound in which the meso position of the heptamethine chain is substituted by 4-pyridyl. SOLUTION: The heptamethinecyanine compound is represented by the formula (wherein Z1 and Z2 are each a five-membered or six-membered heterocycle-forming atomic group, provided that a benzene ring or a naphthalene ring may be fused with the heterocycle; Y1 and Y2 are each a substituent on the heterocycle or the fused ring, carboxyl, sulfoamide or the like; X is an anion; and n is 0 or 1) and is used as a near-infrared absorbing dye. The heptamethinecyanine compound is dissolved in an organic solvent such as methanol or an alkaline aqueous solution, and the concentration of the formed solution is adjusted to obtain an ink. This ink is mixed with a binder such as gelatin and a film hardener such as 1,2-bis(sulfonylacetamide)ethane, and the resulting mixture is applied to a transparent support in a coating weight of 0.001-1g/m2 of the heptamethinecyanine compound.