Electrolyte-Coordination-Induced Electrochemical Multiple Electron Oxidation of 2,5-Diarylthiophenes

Abstract

Chalcogenophene is a five membered aromatic ring containing group 16 elements, and widely used for the design of small molecule or polymer based organic devices. Previously, we have reported a thorough discussions on the electrochemical redox chemistry of tellurium-containing chalcogenophenes, tellurophene (N. Shida, H. Nishiyama, F. Zheng, S. Ye, D. S. Seferos, I. Tomita, S. Inagi, Communications Chemistry, 2019, 2, 124.). We found that the electrochemical oxidation of 2,5-diaryltellurophene in non-coordinating electrolyte resulted in one-electron oxidation product, while two-electron oxidation preferably proceeded in coordinating electrolyte. These results suggest that the design of electrolyte crucially affect the redox chemistry of chalcogenophenes.In this study, we report that the electrochemical redox behavior of 2,5-diarylthiophene also varies significantly depending on the coordination of the electrolyte. Specifically, we have found that the coordination of the electrolyte alters the number of electrons in the oxidation of 2,5-diarylthiophene. It was also found that the species generated by the multiple electron transfer in coordinating electrolyte showed a unique reactivity, and proceeded to an unprecedented dimerization reaction to give sulfonium salts.