Journal of Physical Chemistry A, Vol.104, No.41, 9385-9394, 2000
Electron transfer in aromatic solvents: The importance of quadrupolar interactions
Molecular solvation calculations are performed on a donor-bridge-acceptor (DBA) molecule in polar and nonpolar environments. A strictly dipolar treatment of solvation reproduces experimental values of the reaction free energy, Delta (r)G, determined in nondipolar and weakly dipolar aromatic solvents but does not simultaneously predict accurate values of Delta (r)G in highly dipolar solvents. By contrast, a solvation model that includes contributions from solvent dipole and quadrupole moments (J. Chem. Phys. 1999, ill, 3630(1)) reproduces Delta (r)G values over a large polarity range. The reliability of the predicted Delta (r)G and solvent reorganization energies, lambda (o), are assessed through fitting experimental rate data. The fits display good agreement with the experimental data and the donor-acceptor electronic couplings derived via these analyses agree with prior determinations. The availability of a model that generates reasonable predictions of Delta (r)G and lambda (o) allows a first exploration of the temperature dependence of solvent mediated electronic coupling.