Nanoclusters as Deep-Red Light-Absorbing Photocatalysts for Laser- or LED-Driven Povarov Cyclization

Photocatalysis is primarily initiated with ultraviolet/blue light, which has several drawbacks, namely, deficiencies in reaction efficiency, and scalability. Designing catalysts that can absorb low-energy light offers a promising solution aiming at these drawbacks. In this study, we showed atomically precise gold nanoclusters serve as deep-red-absorbing photocatalysts towards Povarov-type reactions driven by laser or LED irradiation, giving rise to complex tricyclic N-heterocyclic compounds derived from bioactive molecules. Mechanistic studies revealed that the Au₁₅ cluster demonstrates two-photon absorption when excited by a 700 nm laser, while maintaining a single-photon excitation process under red LED irradiation. Furthermore, the versatility and broad applicability of the Au₁₅ photocatalyst were underscored through batch-scalable photoreactions and various other deep-red light-induced reactions. Overall, the combination of nonlinear optics and photocatalysis of metal nanoclusters provides a new avenue for deep-red photocatalysis with continuous and scalable capabilities.