Influence of Temperature on Rotational Dynamics of 3B7D2HC-2-one Molecule in Non-polar, Polar, and Polar Aprotic Solvents

Rotational dynamics of 3-(3H-2l4-benzo[c]isothiazol-2-yl)-7-(diethylamino)-2H-chromen-2-one (3B7D2HC-2-one) is studied using steady-state fluorescence depolarization and time-resolved fluorescence techniques in non-polar, polar and polar aprotic solvents by varying temperatures. Computational calculations are performed using Gaussian 09 software. Over the general solvatochromic method, an advanced thermochromic shift method is used to estimate dipole moments. Experiment rotational diffusion of 3B7D2HC-2-one in methanol indicates slow rotation over the other two solvents. Further, experiment rotational diffusion is analyzed using hydrodynamic and Quasi-hydrodynamic theories. The observed reorientation time follows the trend as predicted by quasi-hydrodynamic models.