Synthesis and characterization of heptamethine cyanine dyes

A series of meso-chlorine substituted heptamethine-cyanine dyes and related heptamethine cyanine dyes unsubstituted on the vinyl chain were synthesized by condensation of 2,3,3-trimethyl indolenium salts with reactive intermediates, 2-chloro-formyl-3-hydroxy-methylenecyclohexene or N-[5-(phenylamino)-2,4-phentadienylidene] aniline monohydro-chloride. The structures of the dyes were characterized by Virtue of H-1-NMR, C-13-NMR, IR, MS, etc. The reaction conditions and physicochemical properties of the dyes were extensively explored with classical photo-physical techniques.