Proton-coupled electron transfer in a pivaloyl-substituted dihydro-tetraazapentacene

Abstract

Within the heteroacene family, azapentacenes have received much attention in organic electronic devices due to their unique physico-chemical properties. This is particularly true for the 5,14-dihydro-5,7,12,14-tetraazapentacene despite its poor solubility in organic solvents which logically hindered the study of its electrochemical behavior. Consequently, we disclose herein the synthesis and characterization of the soluble 6,13-dipivaloyl-5,14-dihydro-5,7,12,14-tetraazapentacene as well as its aromatic counterpart, the 6,13-dipivaloyl-5,7,12,14-tetraazapentacene. These compounds were used as models to fully characterize all the intermediates generated during their electrochemical processes (oxidation and reduction) with a combined approach using complementary chemical, (spectro)-electrochemical, theoretical and spectroscopic techniques. Our results demonstrate the 6,13-dipivaloyl-5,14-dihydro-5,7,12,14-tetraazapentacene ambipolar redox behavior at both cathodic and anodic regime leading to drastic color changes through proton-coupled electron transfer occuring in a totally reversible fashion.