The use of polymetallophthalocyanines as working electrode achieves dehydrogenase-like electrochemical oxidation of thioethers with excellent Faradaic efficiency over 96.3% and nearly 100% product distribution to sulfoxides, along with a high conversion rate of 0.238 mmol h⁻¹, outperforming carbon paper electrodes.

Abstract

The selection of electrode materials is critical to the reactivity and selectivity for organic electrosynthesis. In this work, we for the first time use polymetallophthalocyanines (pMPcs) as working electrode for the efficient and highly selective oxidation of sulfide. pMPcs was found to be able to mediate sulfide oxidation with dehydrogenase-like activity, in which water acts as an oxygen source, for a broad substrate scope, including pharmaceuticals. Among the pMPcs electrodes, pFePc exhibits the highest catalytic selectivity with a faradaic efficiency (FE) of 96.3% and nearly 100% product distribution for the oxidation of sulfides to sulfoxides, as well as the highest conversion rate of 0.238 mmol h⁻¹. Studies combining spectroscopic experiments and computational approaches reveal that the mechanism of oxidation of sulfide involves the proton-coupled oxidation of Fe─OH₂ to generate Fe═O intermediates on the metal atom of the metal-N₄ units of pMPcs. This work highlights the potential for the application of conductive framework materials in organic-electrical synthesis.