Photophysical investigations of the solvent polarity effect on the properties of coumarin-6 dye

Photophysical properties of coumarin-6 dye in different solvents reveal its behavioural differences in non-polar and other solvents. Where the photophysical properties of the dye follow more or less linear correlation with Lippert-Mataga solvent polarity function for moderate to higher polarity solvents, they undergo unusual deviations in non-polar solvents. It is inferred that the dye adopts different conformations at its 7-NEt2 group in non-polar and other solvents, which is also supported by results from quantum chemical calculations.