Intermolecular proton transfer in anionic complexes of uracil with alcohols.Harańczyk M, Rak J, Gutowski M, Radisic D, Stokes ST, Bowen KH Jr.
Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland.
A series of 18 alcohols (ROH) has been designed with an enthalpy of deprotonation in the gas phase (H(DP)) in the range 13.8-16.3 eV. The effects of excess electron attachment to the binary alcohol-uracil (ROH...U) complexes have been studied at the density functional level with a B3LYP exchange-correlation functional and at the second-order Møller-Plesset perturbation theory level. The photoelectron spectra of anionic complexes of uracil with 3 alcohols (ethanol, 2,2,3,3,3-pentafluoropropanol, and 1,1,1,3,3,3-hexafluoro-2-propanol) have been measured with 2.54 eV photons. For ROHs with deprotonation enthalpies larger than 14.8 eV, only the ROH...U- minimum exists on the potential energy surface of the anionic complex. For alcohols with deprotonation enthalpies in the range 14.3-14.8 eV, two minima might exist on the anionic potential energy surface, which correspond to the RO-...HU* and ROH...U- structures. For ROHs with deprotonation enthalpies smaller than 14.3 eV, the excess electron attachment to the ROH...U complex always induces a barrier-free proton transfer from the hydroxyl group of ROH to the O8 atom of U, with the product being RO-...HU*.
PMID: 16852671 [PubMed]