Solvents effect on the absorption and fluorescence spectra of 7-diethylamino-3-thenoylcoumarin: Evaluation and correlation between solvatochromism and solvent polarity parameters

•DETC is a well known laser dye in the blue-green region.•Solvatochromic correlations are used to estimate excited state dipole moment (μe).•It is observed that μe > μg.•Specific solute–solvent interaction is operating in the system.•No synergistic effect is observed in the preferential study.

Effect of solvents of varying polarities on absorption and fluorescence spectra and dipole moment of laser dye: 7-diethylamino-3-thenoylcoumarin (DETC) has been investigated. A small band shift is obtained in the absorption spectra compared to emission spectra. The spectral shifts were correlated with Catalan’s parameters using linear solvation energy relationship. It reveals that non-specific interaction measured by solvent polarity has more influence on absorption and solvent dipolarity contribution is significant in case of fluorescence. A bathochromic shift observed in absorption and emission spectra with increasing solvent polarity, which implied that the transition involved is π → π∗. The solvatochromic correlations were used to estimate the excited state dipole moment using experimentally determined ground state dipole moment. The observed single-state excited state dipole moment is found to be greater than the ground state.

Graphical abstractEffect of solvents of varying polarities on absorption and fluorescence spectra and dipole moment of laser dye: 7-diethylamino-3-thenoylcoumarin (DETC) has been investigated. A small band shift is obtained in the absorption spectra compared to emission spectra. The spectral shifts were correlated with Catalan’s parameters using linear solvation energy relationship. It reveals that non-specific interaction measured by solvent polarity has more influence on absorption and solvent dipolarity contribution is significant in case of fluorescence. A bathochromic shift observed in absorption and emission spectra with increasing solvent polarity, which implied that the transition involved is π → π∗. The solvatochromic correlations were used to estimate the excited state dipole moment using experimentally determined ground state dipole moment. The observed single-state excited state dipole moment is found to be greater than the ground state.Figure optionsDownload full-size imageDownload as PowerPoint slide