Electrochemical behaviour of hypocrellin A in acetonitrile and aqueous micellar media
Abstract
The electrochemical behaviour of hypocrellin A (HAH2) has been studied in acetonitrile and in aqueous micellar media. In acetonitrile (CH3CN) the two successive one-electron transfers are reversible on the cyclic voltammetry time scale and allow different reduced forms of HAH2 to be produced by exhaustive electrolysis. In addition, the one-electron reduction of HAH2 has been studied by UV-visible and EPR spectroscopy, showing that the one-electron transfer is associated with a protonation phenomenon leading to the formation of HAH2•− and HAH3•. In an aqueous micellar medium the first reduction step behaves similarly to that in an organic medium and has allowed us to establish the influence of the pH value on E1/2 and to determine the two pKa values of HAH2 , while pKa values of the one-electron reduced forms of HAH2 have been evaluated.