Substrate‐Selective Capture by Host‐Stabilized Charge Transfer: Macrocyclic‐Confined Supramolecular Photocatalyst in Aqueous Media

ABSTRACT The rational design of aqueous‐phase supramolecular catalysts that integrate substrate recognition, activation, reaction selectivity, and recyclability remains a significant challenge. This work presents a cucurbit8uril (Q8)‐based supramolecular photocatalyst, TMV 8+ @Q8 , which selectively encapsulates aromatic sulfide substrates via host‐stabilized charge transfer (HSCT) interactions while markedly enhancing singlet oxygen ( 1 O 2 ) generation. Under visible‐light irradiation, the substrate‐TMV 8+ @Q8 system facilitates the efficient catalytic oxidation of aromatic sulfides to sulfoxides. Competitive displacement experiments confirm that product desorption is substrate‐driven, enabling catalyst regeneration. Crucially, the Q8 cavity plays a multifaceted role by enhancing substrate activation through HSCT, promoting 1 O 2 ‐mediated oxidation via confinement effects, and enforcing selectivity through size exclusion. These findings establish a new paradigm for supramolecular photocatalysis, wherein macrocyclic confinement concurrently enhances substrate recognition, catalytic efficiency, and recyclability. This study thereby provides a strategic blueprint for designing enzyme‐inspired supramolecular photocatalysts operable in aqueous media.