Regenerative Photocatalysis. Pushing the boundaries of electron-transfer processes

Aiming at expanding the reactivity domain of photocatalysis, we discovered the peculiar behaviour of a purely organic catalyst that upon light-irradiation undergoes controlled disruption, substrates activation, and regeneration in an unconventional regenerative catalytic cycle. Upon light-irradiation the molecule cleaves generating three diverse species capable of unlocking both an oxidative and a reductive quenching manifold at once. Under this dual catalytic regime, it is possible to access a redox window as large as 5.7 V under simple visible-light (400 nm) irradiation. We herein demonstrate the power of regenerative photocatalysis for the activation of a variety of structurally diverse inert substrates throughout both a reduction and an oxidation process. This unconventional mechanistic scenario is revealed by a combination of spectroscopic and optical techniques, supported by density functional theory calculations. Two of the longstanding problems in the field of organic photocatalysis: (i) the structural fragility of the photocatalysts, and (ii) the limited redox window accessible under visible-light irradiation, are the strengths of regenerative photocatalysis. Using a simple organic molecule is now possible to overcome the classical thermodynamic limits of electron-transfer processes.