Asymmetrical trimethine cyanine dyes for high capacity optical recording medium

A dye material having an asymmetrical trimethine cyanine structure as represented by formula (I), and its maximum absorption wavelength being in between 550-590 mn that can be used as recording material for write once optical disk on which digital information is recorded by using laser beam with wavelength from 620 nm to 660 nm,

• wherein
• R1 is a hydrogen atom, a methyl group, or an ethyl group,
• R2 and R3 each is, independent from each other, a substituted or unsubstituted C1 to C12 alkyl group,
• A⊖ is an anion selected from the group consisting of halogen atoms, ClO463 , BF4⊖, PF6⊖, SbF6⊖, CF3SO3⊖, C2F5SO3⊖, CF3COO⊖, and CH3C6H4SO3⊖,
• X is hydrogen, alkyl, alkoxy, halogen, nitro, or fused benzene,
• Y is hydrogen, alkoxy, halogen, alkyl, aryl, alkoxycarbonyl, aryloxycarbonyl, alkylamine, arylamine, alkylamide, arylamide, alkylsulfonyl, aryl sulfonyl, alkoxysulfonyl, aryloxysulfonyl, nitro, or cyano groups.