Electronic description of four flavonoids revisited by DFT method

Structural and electronic characteristics of four flavonoids, namely quercetin, luteolin, catechin and taxifolin, have been revisited by means of B3LYP density functional. Rotation energy of the catechol moieties together with HOMO-LUMO, dipole moments analyses are reported for each flavonoid. Deprotonation and hydrogen abstraction energies of the O3H and O4'H hydroxyl groups are compared and analyzed with the help of an electronic description for each structure. Our results put forward the significant role of pi-delocalization upon stabilization but have also shown that inductive effects play a major role in the stabilization of deprotonated forms. Inspection of the charge transfer together with analysis of a simple model of catechol has also demonstrated the relative independence of each structural motif when hydrogen abstraction processes are considered. (C) 2008 Elsevier B.V. All rights reserved.