Electroreduction of 8-(thiophen-2-yl)- and 8-(phenyl)-dipyrrometheneboron difluorides. A mechanistic study by cyclic voltammetric digital simulation

摘要

The electrochemical reduction of two meso-substituted dipyrrometheneboron difluorides, BODIPYs, 8-(thiophen-2-yl)-dipyrrometheneboron difluoride and 8-(phenyl)-dipyrrometheneboron difluoride, was studied in acetonitrile. Both compounds underwent two consecutive electron transfers to produce the radical anion and dianion species. The cyclic voltammograms show that the current intensity of the second cathodic peak is much smaller than the first one-electron reduction process. The current intensity ratio of the two peaks (i(IIc)/i(Ic)) was analyzed as a function of the BODIPY concentration and of the scan rate; the results indicate that dimerization reactions are responsible for the remarkable current decrease in the second electroreduction. Digital simulations of the experimental cyclic voltammograms show that the three possible dimerization reactions, radical anion-radical anion, radical anion-dianion and neutral-dianion, have a different effect on the voltammetric behavior. Thus, the simulation analysis allowed to elucidate the reaction mechanism. (C) 2019 Elsevier Ltd. All rights reserved.