Accumulation of Four Electrons on a Terphenyl (Bis)disulfide

The activation of N-2, CO2 or H2O to energy-rich products relies on multi-electron transfer reactions, and consequently it seems desirable to understand the basics of light-driven accumulation of multiple redox equivalents. Most of the previously reported molecular acceptors merely allow the storage of up to two electrons. We report on a terphenyl compound including two disulfide bridges, which undergoes four-electron reduction in two separate electrochemical steps, aided by a combination of potential compression and inversion. Under visible-light irradiation using the organic super-electron donor tetrakis(dimethylamino)ethylene, a cascade of light-induced reaction steps is observed, leading to the cleavage of both disulfide bonds. Whereas one of them undergoes extrusion of sulfur to result in a thiophene, the other disulfide is converted to a dithiolate. These insights seem relevant to enhance the current fundamental understanding of photochemical energy storage.

Automated summary

This study reports on a terphenyl compound containing two disulfide bridges, which undergoes four-electron reduction in two separate electrochemical steps for electron storage under light-driven conditions. Light-induced cascade reaction steps are observed under visible-light irradiation using an organic super-electron donor, leading to the cleavage of both disulfide bonds.