Electrochemical oxidation of flavonoids: PM6 and DFT for elucidating electronic changes and modelling oxidation potential

Abstract A set of 14 flavonoids and their cation and radical forms involved in the first electrochemical oxidation step, E p1 , were optimized using semi-empirical PM6 and DFT in vacuo methods. For the differences in Net atomic charges (ΔNAC Cat.-Neut. ), by which we previously used to determine active OH oxygens by PM6 in water (which were in agreement with the literature), both PM6 and DFT gave doubtful results in some cases. In accordance with our previous research, the sum of Atomic orbital spin populations on carbon atoms in the skeleton of radicals ( Σ s C AOSP Rad. ) calculated using both PM6 and DFT, is lower for flavonoids more prone to oxidation. Although the models for the estimation of E p1 based on Σ s C AOSP Rad. calculated by PM6 method gave somewhat better statistics than those calculated using DFT, the statistics obtained by both methods in vacuo were worse than those obtained by PM6 in water calculations.