Solvent effects upon the charge -transfer reaction of the ADMA molecule in the excited state

Most chemical reactions occur in the solution phase. Although in most cases the solvent itself does not take part in the reaction, it is able to influence the reaction profoundly, giving rise to "solvent effects". Solvents are influence the outcome of charge-transfer reactions via two methods. First, the solvent-solute interactions can lower the activation barrier of the charge-transfer reaction. Secondly, solvent orientational fluctuations provide energy to the solute so that the solute can undergo charge transfer. The first interaction is thermodynamic, while the second is dynamic in nature.;In order to investigate the contributions of these effects we have utilized the ADMA (1-(9-anthryl)-3-(4-dimethylaniline)propane) molecule as a fluorescence probe. ADMA forms an excited state charge-transfer complex (exciplex) in the excited state. We have measured the emission spectra of ADMA in a series of neat solvents and solvent mixtures. Our results demonstrate that the solvation of the ADMA exciplex can be well interpreted by the existing theories.;We have also investigated the kinetics of the charge-transfer in ADMA. Applying our solvation results to our time-resolved data, we demonstrate that the kinetics of charge transfer in ADMA is well characterized by Marcus Theory and that in contrast with the interpretation of previous workers the charge transfer process is not diffusion controlled.