Dual tuning of nodes and functional guests of polyoxometalate@metal–organic frameworks for enhanced photocatalytic oxidative coupling

Abstract

Metal–organic frameworks are versatile platforms for photocatalysis owing to their facile capacity to incorporate active sites within organic linkers, nodes and open channels. However, the dual tuning of both nodes and functional guests for enhanced photocatalytic performance remains largely unexplored. Herein, we report the incorporation of functional polyoxometalate guests, {PM₁₀V₂} (M = Mo or W), into isoreticular 2D MOFs that are constructed from an anthraquinone-derived ligand and dinuclear nodes of {Cd₂X(H₂O)₄} (X = Br or I), yielding isostructural polyoxometalate@metal–organic frameworks, denoted as POMOF 1–POMOF 3. By systematically varying the node from {Cd₂Br(H₂O)₄} to {Cd₂I(H₂O)₄} and the polyoxometalate guest from {PMo₁₀V₂} to {PW₁₀V₂}, we achieve a structural evolution from POMOF 1 to POMOF 3. Notably, POMOF 1 shows the highest activity towards photocatalytic oxidative coupling of benzylamine and its derivatives due to the synergistic effect of {PMo₁₀V₂} and {Cd₂Br(H₂O)₄}, which facilitates the highest photocurrent and an optimal band gap distribution for reactive oxygen species formation and substrate activation. This study demonstrates a promising strategy for designing photocatalytically active materials with enhanced performance via dual regulation.