Study on Solvent Effect and Estimation of Dipole Moments of Laser Dye 3ADHC

Abstract

In this paper solvent effect of 3-acetyl-7-(diethylamino)-2H-chromen-2-one(3ADHC) dye molecule have been studied by solvatochromic shift method. The electronic absorption and emission spectra of the dye molecule were recorded in a variety of polar protic and polar aprotic solvents at room temperature (298K). Solvatochromic shifts, specifically bathochromic (red) shifts were observed in the absorption and emission spectra as a result of solvent polarity, it signifies the π→π* transition involved. The ground state dipole moment and excited state dipole moment of 3AHDC is calculated using solvent correlation methods. Obtained results are in good agreement with the ground state dipole moment calculated by Gaussion computational methods. The ground and excited state dipole moment of the 3ADHC have also been computed from ab initio calculations and compared with those determined experimentally. It has been found that excited-state dipole moment (μe) is greater than ground-state dipole moment (μg) for the title molecule. The increase in dipole moment in the excited singlet states ranges between 3.93 to 8.60D for 3ADHC. This demonstrates that test molecule is more polar in excited states than in ground states for all the solvents used. The spectral changes were analyzed by Kamlet-Taft parameters.