Solvent dielectric effects on isomerization dynamics: Investigation of the photoisomerization of 4,4′-dimethoxystilbene and t-stilbene in n-alkyl nitriles

Abstract

New data for the photoisomerization dynamics of t‐stilbene and 4,4’‐dimethoxystilbene in polar solvents are reported. These data demonstrate that in n‐alkyl nitriles, nonassociated polar solvents, it is possible to extract a solvated barrier for the isomerization. This result is contrasted with recent studies in n‐alkyl alcohols, associated polar solvents, where this separation is not possible and clarifies the origin of the changing barrier height in n‐alkyl alcohols. Comparison of reduced isomerization rates with models of chemical reaction dynamics in solution are drawn. Good agreement of the data with a coupled oscillator model is found.