two carbon atoms, R2 is a divalent organic group having at least two carbon atoms, R3 is an alkali metal ion, ammonium ion, hydrogen or an organic group having one to thirty carbon atoms, and n is 1 or 2; said compound (B) having at least one functional group selected from the group consisting of an amino group and an amide group, said compound (B) also having at least one photoreactive moiety sel