Multifunctional Tubular Organic Cage‐Supported Ultrafine Palladium Nanoparticles for Sequential Catalysis

Abstract The imine condensation reaction of 5,5′‐(benzo[ c ][1,2,5]thiadiazole‐4,7‐diyl)diisophthalaldehyde with cyclohexanediamine resulted in a shape‐persistent multifunctional tubular organic cage (MTC1). It exhibits selective fluorescence sensing towards divalent Pd ions with a very low detection limit (38 ppb), suggesting effective complexation between these two species. Subsequent reduction of MTC1 and Pd(OAc) 2 with NaBH 4 afforded a cage‐supported catalyst with well‐dispersed ultrafine Pd nanoparticles (NPs) in a narrow size distribution (1.9±0.4 nm), denoted as Pd@MTC1‐1/5. Such ultrafine Pd NPs in Pd@MTC1‐1/5, in cooperation with photocatalytically active MTC1, enable efficient sequential reactions involving visible light‐induced aerobic hydroxylation of 4‐nitrophenylboronic acid to 4‐nitrophenol and the following hydride reduction with NaBH 4 . This is the first example of a multifunctional organic cage capable of sensing, directing nanoparticle growth, and catalyzing sequential reactions.