Solvent Effects on the UV–vis Absorption and Emission of Optoelectronic Coumarins: a Comparison of Three Empirical Solvatochromic Models

Coumarins often function in the solution phase for a diverse range of optoelectronic applications. The associated solvent effects on the UV–vis absorption and/or fluorescence spectral shifts of coumarins need to be understood in order that their photochemistry can be controlled. To this end, three different empirical solvatochromic models are assessed against 13 coumarins. The two generalized solvent scales developed by Catalan and co-workers demonstrate comparable performance to the popular Taft–Kamlet solvatochromic comparison method. A combinatorial approach to determine the best-fit equations in all of the empirical models is applied; this involves both statistical best-fits and the physical validation of the resulting parameters, based on the molecular structures of solvents and solutes and their corresponding interactions. The findings of this approach are used to extract useful information about different aspects of solvent effects on the solvatochromism of coumarins.