Synthesis of Fluorescent Dichromophoric Benzothiazole-Based Polyenes

Syntheses of some novel dichromophoric cyanine dyes based on 2-aminobenzothiazoles have been reported. Their highly extended conjugated systems are in symmetrical and unsymmetrical structures, both of which are divided into two electron-rich and electron-poor series. The sixteen synthesized compounds absorb visible light in the region of 462-523 nm in ethanol in deep orange, red and purple color with high molar absorption coefficients (ε: 2.1 - 4.4 x 104 M-1.cm-1). Besides the study of their electronic spectroscopic properties, broad solvatochromic effects have been observed 70-200 nm shifts in nine different solvents. In fluorescence spectroscopic studies, their emissions have been observed to be 400-500 nm at excitation wavelengths 347-375 nm in DMF.