Solvent effects on electronic transitions in several coumarins

Absorption and emission energies of four coumarins (coumarins 1, 102, 152, 153) in a variety of alcohols and aprotic solvents are analyzed in terms of the solvatochromic parameter and dielectric continuum models. Although the results for all four solutes are well described using the empirical solvatochromic parameters, some deviations from the predictions of the more theoretically based approach are observed in alcohol solvents, particularly for those coumarins expected to exhibit better hydrogen-bond-accepting ability.