Regenerative Photocatalysis

Aiming to expand the reactivity domain of photocatalysis, we discovered the peculiar behaviour of a purely organic catalyst. Upon light irradiation, it undergoes controlled disruption, substrate activation, and regeneration in an unconventional regenerative catalytic cycle. Upon visible-light irradiation (400 nm), the molecule cleaves, generating three different species capable of simultaneously unlocking opposed yet productive oxidative and reductive manifolds under irradiation. These subunits recombine at the end of each catalytic cycle, generating the original scaffold. We herein demonstrate the power of regenerative photocatalysis for activating a variety of structurally diverse inert substrates via both a reduction process and an oxidation process, accessing a redox window as large as 5.7 V. The mechanistic situation is revealed by a combination of spectroscopic and optical techniques, supported by density functional theory calculations. Two longstanding problems for organic photocatalysis become strengths for regenerative photocatalysis, namely: i) the structural fragility of the photocatalysts, and ii) the limited redox window accessible under visible-light irradiation.