INFLUENCE OF POLAR-SOLVENTS ON REACTION DYNAMICS - PHOTOISOMERIZATION STUDIES OF DIHYDROXYSTILBENE

The photoisomerization kinetics of 4,4′-dihydroxystilbene in polar solvents, n-alkyl alcohols and n-alkanenitriles, was investigated as a function of temperature at ambient pressure. Although it is possible to define an activation barrier within a restricted set of solvents, the activation energy depends on both the magnitude and the dynamics of solvation. Comparison of these results with earlier work on trans-stilbene and 4,4′-dimethoxystilbene demonstrates their generality and probes effects of hydrogen bonding with the hydroxyl group. A comprehensive view of the reaction dynamics where the solvent polarization field is intimately coupled to the "intramolecular" reaction coordinate is discussed. © 1990 American Chemical Society.