Spotlight on a Recent Journal of the American Chemical Society (JACS) Publication…
[[{"fid":"1231","view_mode":"default","fields":{"format":"default","field_file_image_alt_text[und][0][value]":"","field_file_image_title_text[und][0][value]":""},"type":"media","link_text":null,"attributes":{"class":"panopoly-image-original media-element file-default"}}]]
Dmitry Matyushov from the School of Molecular Sciences as well as the Department of Physics and co-workers including Ana Moore, Thomas Moore and Devens Gust from the School of Molecular Sciences at Arizona State University have recently reported a straightforward verification of Marcus (Nobel Laureate in Chemistry 1992) theory.
Oxidation–reduction reactions are characterized by the transfer of an electron from a donor molecule to an acceptor molecule. Conventional wisdom had dictated that the electron-transfer rate should have a linear relationship to the exergonicity, or change in free energy, of the reaction. But in 1956, Rudolph Marcus predicted an unexpected bell-shaped dependence of the reaction rate on the Gibbs free energy, whereby electron-transfer rates become slower with larger energy differences between the reactants and the products. The Marcus law has traditionally been confirmed by altering the chemical structures of donors and acceptors.
Matyushov and co-workers characterized the dependence of the electron-transfer rate on the medium temperature using a fullerene–porphyrin dyad (DOI: 10.1021/jacs.6b04777). Without modification of the chemical structure, electron transfer in this system also demonstrates bell-shaped dependence when plotted against inverse temperature. The authors explain that this unusual temperature dependence is because of the strong decrease in the energy required for solvent reorganization with increasing temperature.