Solvent reorganization energies measured by an electron transfer reaction in211 supercritical ethane

摘要

The intermolecular electron transfer reaction between a biphenyl anion and pyrene211u001ein supercritical ethane was studied using pulse radiolysis. Second-order electron 211u001etransfer rates were found to be of the order of 10(sup 11) M(sup (minus)1) s(sup 211u001e(minus)1). The rate constants appear to be approximately constant over the 211u001epressure range 55-133 bar. Two possibilities are discussed that could explain the 211u001epresent results: solvent clustering; or a dependence of the solvent 211u001ereorganization energy on pressure. Reorganization energies E(sub r) of non-polar 211u001esupercritical ethane were estimated from the observed rate constant using the 211u001emodified Marcus equation. E(sub r) may be larger than normally expected for non-211u001epolar solvents because of density fluctuations.