Synthesis and absorption spectra of polymethine dyes — Derivatives of substituted thieno- and indolothiazoles

Abstract

Cyanine, merocyanine, and styryl dyes that are derivatives of halo-, alkyl-, alkylene-, and arylthieno[2,3-d]thiazoles and halo- and alkylindolo[3,2-d]thiazoles were synthesized. It is shown that both electron-donor and electron-acceptor substituents in the 5 and 5′ positions of the heteroresidues of thienothiazolocarbocyanines lead to a more uniform distribution of the electron density in their chromophore than in the unsubstituted dye and to a bathochromic shift of the absorption maximum. Methyl groups in the heteroresidues of indolothiazolocarbocyanines give rise to a small bathochromic effect.