Solvent effect on the spectroscopic properties of 8EMOHCC

Abstract

This paper reports the absorption and fluorescence spectra of ethyl 8-methoxy-2-oxo-2H-chromene-3-carboxylate 8EMOHCC has been recorded in various solvents of different polarities at room temperature. Solvatochromic shifts, specifically bathochromic (red) shifts were observed in the absorption and fluorescence spectra. The ground state dipole moment of 8EMOHCC was obtained from quantum chemical calculations. Solvatochromic correlations were used to estimate the ground state (µg) and excited state (µe) dipole moments. The quantum chemical calculations of ground state dipole moment is in good agreement with experimentally calculated ground state. The exited state (μe) dipole moments were estimated using Lippert’s, Bakhshiev’s and Kawski-Chamma-Viallet’s equations by using the variation of Stoke’s shift with the solvent polarity. The excited state dipole moments are observed to be greater than the ground state dipole moment, indicating a significant redistribution of the π-electron densities in excited state for 8EMOHCC. Finally bathochromic shift is observed upon increasing the polarity of the solvents for the molecule indicating π→π∗. ansition. Further, the change in dipole moments (Δµ) were calculated from solvatochromic shift method, microscopic solvent polarity parameter (ETN.)nd the value were correlated. The variations in spectra were analyzed by Kamlet-Taft parameters and it is observed that, the influence of HBD (β) is more than HBA (α) for emission process and Stoke’s shift, whereas the influence of HBD (β) is more than HBA (α) for absorption process for 8EMOHCC.