DFT insight into o-semiquinone radicals and Ca2+ion interaction: Structure, g tensor, and stability

Abstract

Density functional theory methods were employed to elucidate the interactions between calcium ions and various o-semiquinone radicals mimicking the interactions occurring in biochemical systems. Predicted changes in the molecular and electronic structures of the radicals on Ca2+ coordination were correlated with the changes of g tensor and compared with those exerted by Mg2+ ions (reported by us previously). In order to broaden the insight into the differences between the Mg2+ and Ca2+ complexes, their relative stability was estimated on the basis of theoretically predicted Gibbs energies for the process of the complex formation. © The Author(s) 2013.