Solvatochromic effect on the photophysical properties of two coumarins.

The absorption and emission spectra of two coumarins namely 7, 8 benzo-4-azidomethyl coumarin (C(1)) and 6-methoxy-4-azidomethyl coumarin (C(2)) have been recorded at room temperature in solvents of different polarities. The ground state dipole moments (μ(g)) of two coumarins were determined experimentally by Guggenheim method. The exited state (μ(e)) dipole moments were estimated from Lippert's, Bakhshievs and Chamma-Viallet's equations by using the variation of Stoke's shift with the solvent dielectric constant and refractive index.

Effect of solvent polarity on the fluorescence quenching of biologically active 5BAMC by aniline in binary solvent mixtures.

The fluorescence quenching of 5, 6-benzo-4-azidomethyl coumarin (5BAMC) by aniline have been carried in different solvent mixtures of benzene (BN) and acetonitrile (AN) at room temperature by steady state fluorescence measurements. The quenching is found to be appreciable and a positive deviation from linearity was observed in the Stern-Volmer plot for the fluorophore in all the solvent mixtures. Various parameters for the quenching process have been determined using the extended S-V equation and have been found to be dependent on the solvent polarity.