Synthesis and spectroscopic study of 2,7-diethylamino-2-oxo-2H-chromen-3-yl benzothiazole-6-sulfonyl chlorides and its derivatives

The electronic absorption and emission spectra of the label and its derivatives in organic solvents of different polarity, micellar systems and in aqueous buffered media are investigated. The label and its derivatives exhibited more or less the same excitation and emission wavelength around 470 and 520 nm, respectively. Maximum fluorescence quantum yield for aniline derivative was observed in ethyl acetate while minimum yield was observed in water. In micellar systems, maximum quantum yield was observed in the presence of Tw-20 for the label while proline derivative gave maximum enhancement in the presence of Tw-80. The results reflect the importance of medium effect on the fluorescence intensity and molar absorptivity of the label and its derivatives.