Zinc–Salen Anchored Multidentate Two‐Dimensional Metal–Organic Framework for Coupling Photoredox of Oxygen and Benzylamine

Abstract

ABSTRACT Two‐dimensional π‐conjugated metal–organic frameworks (2D MOFs) are promising solar‐driven catalysts, but often suffer from sluggish charge separation due to insufficient strong electron acceptors. To overcome this, two isostructural and heteroporous 2D MOFs, Zn‐HTT, and Zn‐HTD were built from multidentate Zn─O 4 node linkages but differed in active‐site design. Zn‐HTT integrates anchored chelating Zn─N 2 O 2 Salen moieties and Zn─O 4 units, whereas Zn‐HTD contains only Zn─O 4 nodes. The Zn–Salen units in Zn‐HTT narrow the bandgap to 1.99 eV and establish a stronger intramolecular donor–acceptor architecture that drives efficient spatial charge separation. Consequently, Zn‐HTT achieves a high hydrogen peroxide (H 2 O 2 ) photosynthesis rate of 21.9 mmol g −1 h −1 and delivers 94.5% yield of N‐benzylbenzaldimine from the benzylamine photooxidation, significantly outperforming Zn‐HTD (14.2 mmol g −1 h −1 ; 85.6% yield). Mechanistic studies confirm that the Zn–Salen sites serve as superior electron‐accepting and O 2 ‐activating centers, enabling strong *OO intermediate adsorption and highly selective two‐electron oxygen reduction to H 2 O 2 . Moreover, Zn‐HTT exhibits better stability, retaining >91% activity over 10 cycles and showing enhanced thermal resilience, attributable to the robust chelating Zn–Salen linkages. This work demonstrates that integrating metallo–Salen motifs into multidentate 2D MOFs is a viable strategy to boost photocatalytic activity, selectivity, and durability in solar‐driven synthesis.