Synthesis, solvatochromism and estimation of ground and excited state dipole moments of silylated benzothiazole dyes

Abstract Dyes derived from benzothiazoles are an important class of heterocycles that have remarkable photophysical properties. New photoluminescent 2-phenylbenzothiazole derivatives containing different functional groups were synthesized in high yields and used for the synthesis of silylated derivatives. New photoactive structures were fully characterized and their photophysical properties were investigated. The absorption and fluorescence spectra of benzothiazoles in a series of organic solvents were evaluated. The results showed that benzothiazoles are strongly fluorescent showing absorption in the UV region and emission in the blue region with moderate quantum yields and high Stokes shift. The solvatochromism of benzothiazoles was investigated by Lippert and ET(30) Dimroth-Reichardt empirical solvent polarity scales for organic solvents. The dipole moments obtained by Bakshiev and Kawaski-Chamma-Viallet equations revealed that the excited states are more polar than the ground states.