The stabilizing role of intramolecular hydrogen bonding in disubstituted hydroxy-quinones

A voltammetric and theoretical study of a series of quinone derivatives in the presence and absence of hydroxyl groups as substituents is presented. The results indicate that intramolecular hydrogen bonding results in stabilization of the anion radical structure, leading to a shift in potential values for these derivatives toward less negative potentials compared with the unsubstituted quinones. A detailed analysis of the experimental responses reveals that no more coupled chemical reactions must be considered to explain the obtained data. The role of the stabilization of the electrogenerated radical anion by delocalization of the added electron within the structure is discussed on the basis of theoretical results employing density functional theory and the Truhlar model for solvation; also, estimates of the intramolecular hydrogen bond energy are presented. (C) 2013 Elsevier Ltd. All rights reserved.