Bimodal multiphoton catalysis via structural regeneration

Most of the current photocatalytic methodologies for the generation of reactive radical intermediates have limited redox windows and can operate within a single redox manifold. Here, to overcome these constraints, we report a purely organic photocatalyst that operates via a two-photon excitation mechanism, enabling both oxidative and reductive transformations within a unified platform. Upon visible-light irradiation, the molecule undergoes reversible fragmentation into three reactive subunits spanning a 5.7 V redox window. These fragments orchestrate an unusual consecutive light-induced electron-transfer mechanism that enables the orthogonal activation of thermodynamically challenging substrates. The mechanistic scenario is revealed through a combination of spectroscopic and optical techniques, supported by quantum calculations. Selectivity is mainly governed by the activity of a transiently generated catalytic species, whose presence prevents the need for external radical-sorting agents. Finally, the generality of this light-driven radical-coupling reactivity is demonstrated across a broad range of structurally diverse substrates. (Figure presented.)