Reproducing the Solvatochromism of Merocyanines by PCM Calculations

Polarizable continuum methods (PCM) have been widely employed for simulating solvent effects, in spite of the fact that they either ignore specific interactions in solution or only partially reproduce non-specific contributions. Examples of three solvatochromic dyes with a negative, a positive and a reverse behavior illustrate the achievements and shortcomings of PCM calculations, and the causes for their variable success. As shown with a theoretical model that rationalizes and predicts the solvatochromism of phenolate merocyanines based on structural parameters, PCM shortcomings are to be held responsible for their eventual failure in reproducing experimental data.