Model of one-electron transport. Thermodynamic parameters calculation of electron attachment to bound proton of oxyacids A-OH
Emanuel Institute of Biochemical Physics, Russian Academy of Sciences; Kosygina st., 4, Moscow, 119334, Russia; Phone: +7(495)939-7469; E-mail: email@example.com pp. (accepted)
Previously in one-electron transfer model we for the first time obtained experimental results proving possibility of low-energy electron attachment to bound proton in aqueous solution. In condensed medium (e.g. frozen at 77K aqueous solution) oxyacid is able to capture low-energy electron (having energy even less than 1 eV) forming molecular anion. Resulted anion could further dissociate forming hydrogen atom or transfer excess electron to terminal acceptor. The former could be modelled by oxyacid's aqueous solution containing low-energy electrons (e.g. photoinjected). The latter could be modelled by adding terminal acceptor in very low concentration, not sufficient for direct electron transfer from donor to terminal acceptor (diffuse effects are excluded in condensed medium). In this case electron can reach terminal acceptor through electron-conducting medium formed by oxyacid molecules.
We performed calculations of thermodynamic parameters of dissociative electron capture in aqueous solution for a series of inorganic oxyacids: phosphate, sulfate, borate, and two organic acids (formate and acetate). Also we estimated the localization of excess electron. The effect of aqueous solution was included using the polarizable continuum model (PCM). Production ab initio calculations were carried out at the second-order Møller–Plesset perturbation theory (MP2) level to reliably capture the effects of electron correlation. We used the aug-cc-pVDZ Gaussian basis set (polarized double-zeta augmented with diffuse functions to accommodate the ‘swelling’ of anions). The resulting energies (enthalpies) were corrected for zero-point atomic vibrations to yield Gibbs free energies.