Theoretical Modeling of the Redox Thermodynamics of Nucleic Acid Building Blocks in the Condensed Phase

Low-energy solvated electrons can be captured by nitrogenous bases and localized on the nucleic acid to form a stable anion. The interaction between electrons and the bases is related to alterations in the stability and function of nucleic acids. Here, we report the theoretical-computational estimates of the adiabatic electron affinities (AEAs) and the reduction potentials of the nucleobases in solution. Our data show that pyrimidine bases exhibit the highest tendency to form stable anions in both the gas phase and condensed phases (water and <i>N</i>,<i>N</i>-dimethylformamide solutions). The addition of a ribose moiety increases the electron affinities of the nucleobases in the corresponding nucleosides across both environments. Finally, the comparison with the available experimental data shows that our QM/MM approach, based on a statistical-mechanical treatment of the system, is capable of furnishing accurate reduction-free energy differences in the condensed phase.