Heptamethine cyanine compound, near infrared absorbing ink, near infrared absorbing sheet and silver halide photographic material

摘要

A heptamethine cyanine compound is represented by the formula (I): in which each of Z1 and Z2 is an atomic group that forms a five or six-membered heterocyclic ring or a five or six-membered heterocyclic ring condensed with benzene ring or naphthalene ring; each of R1 and R2 is an alkyl group or a substituted alkyl group; each of Y1 and Y2 is carboxyl, a sulfonamido group or a sulfamoyl group; X is an anion; and n is 0 or 1. The present specification also discloses a near infrared absorbing ink, a near infrared absorbing sheet and a silver halide photographic material using the heptamethine cyanine compound as a near infrared absorbing dye.