Quantum Chemical Insights into DNA Nucleobase Oxidation: Bridging Theory and Experiment

The oxidation free energies of DNA nucleobases in aqueous solution are still matter of extensive discussion because of the contrasting results reported so far. With the aim of settling a longstanding debate about the oxidation potentials of DNA constituents, herein we report the results of state-of-the-art DFT-based molecular dynamics simulations, in which the whole solvent environment is modeled at the atomistic level, by using DFT supercell calculations, with periodic boundary conditions. Calculated vertical ionization energies are very close to those observed by photoelectron spectroscopy both in the gas phase and in solution. One-electron oxidation free energies in aqueous solution agree well with the results of differential pulse voltammetry measurements and with those inferred by photoelectron spectroscopy with the aid of theoretical computations to estimate vibrational relaxation.