Solvent Polarity and Environment Sensitive Behavior of Coumarin Derivative

This paper reports an investigation on ground and excited state preferential solvation index (i.e., delta s2) and relative quantum yield of 2-acetyl-3H-benzo[f]chromen-3-one (2AHBC) molecule. The title molecule shows negative values of preferential solvation index in the ground state in different binary solvent mixtures, this confirms that molecule under study is preferentially solvated by 1,4-dioxane (DXN) rather than acetonitrile (ACN). The excited state preferential solvation index is found to be positive which signifies strong predomination of solute-solvent interaction. Synergistic effect is confirmed by the higher values of fluorescence wave maximum in DXN and ACN solvents for 2AHBC. Further, quantum yield of 2AHBC molecule is estimated in solvents of different polarities. It is found that, non-radiative decay constant is more than the radiative decay constant in all the solvents. This is attributed due to intermolecular forces between hydrogen atoms. Relative quantum yield of 2AHBC is found to be inversely proportional to the polarity of the solvents. This is due to the intermolecular charge transfer and bathochromic effect. Whereas, the influence of viscosity of the solvents on quantum yield of 2AHBC is studied and it is confirmed by the Forster-Hoffmann equation.