Light‐Driven Preactivation of 3DPAFIPN into Highly Active Photocatalytic Species

Cyanoarene photocatalysts such as 3DPAFIPN are widely employed in visible-light-driven transformations, yet their intrinsic structural dynamics under irradiation remain poorly understood. Here we reveal that 3DPAFIPN undergoes light-induced reconfiguration into distinct cyclized and radical substitution products, with the parent species ultimately decomposing under reaction conditions. Using a combination of Photo-Chem-ESI-MS and TLC-mapping, we directly monitored the evolution of catalytic forms and identified the cyclized derivatives as the true active species in thiol-yne-ene coupling. The major cyclized product was isolated and structurally confirmed by single-crystal X-ray diffraction, providing unambiguous experimental evidence for light-driven photocatalyst reconfiguration. Compared with the precursor, the cyclized catalysts display enhanced stability against cyanide substitution by radical intermediates and deliver higher efficiency and selectivity. This study establishes a generalizable workflow for dissecting dynamic photocatalyst behavior and extends the ReAct-Light concept, highlighting light-triggered structural evolution as a new design principle for adaptive and robust photocatalytic systems.