Ground and excited state dipole moments of some flavones using solvatochromic methods: An experimental and theoretical study

Abstract

The absorption and fluorescence characteristics of biologically active flavone derivatives 6-Hydroxy-7,3′,4′,5′-tetramethoxyflavone (6HTMF) and 7-Hydroxy-6,3′,4′,5′-tetramethoxyflavone (7HTMF) are studied at room temperature (298 K) in solvents of different polarities. Excited state dipole moments of these compounds have been determined using the solvatochromic shift method based on the microscopic solvent polarity parameter ETN. Dipole moments in excited state were found to be higher than those in the ground state in both the molecules. A reasonable agreement has been observed between experimental and theoretically calculated dipole moments (using AM1 method). Slightly large value of ground and excited state dipole moments of 7HTMF than 6HTMF are in conformity with predicted electrostatic potential maps. Our results would be helpful in understanding use of these compounds as tunable dye lasers, optical brighteners and biosensors.