Solvation and rotational dynamics in acetonitrile/propylene carbonate mixtures: a binary system for use in dynamical solvent effect studies

Equilibrium and nonequilibrium solvation properties as measured by the Stokes shift of coumarin 153 are reported for a series of acetonitrile/propylene carbonate binary mixtures at room temperature. Steady-state spectroscopy shows that the solvent reorganization energy is independent of composition in this mixture. Solvation and rotational times vary nearly ten-fold between the pure solvent limits, in a manner that is correlated to bulk solution viscosity. The wide range of solvation times together with the constant solvent reorganization energy should render this binary system useful for investigating dynamical solvent effects on charge-transfer processes.