In Situ Exfoliation of Cluster-Based 2D MOF into Cu/Co Bimetallic Ultrathin Nanosheets via Post-Synthetic Metalation for Oxidase-Mimic Heterogeneous Catalysis in Aqueous Media.

Metal-organic framework (MOF) nanosheets have emerged as promising platforms for catalytic applications, yet the controlled exfoliation of bulk MOFs into monolayer nanosheets remains challenging. Herein, a cluster-based [Co3.5L3{N(CN)2}H2O]·7H2O (Co7-DCA) MOF, where H2L refers to the phosphonate ligand and its bimetallic derivatives M@Co7-DCA (M = Cu, Zn) were rationally synthesized via a hydrothermal strategy to introduce synergistic heterometal sites and enhanced oxidase-mimic activity. Remarkably, these bimetallic MOFs can be efficiently exfoliated into monolayer nanosheets in methanol, a rare phenomenon for structurally rigid MOFs, enabling in situ formation of ultrathin nanosheets during catalysis. The resulting monolayer nanosheets act as highly efficient oxidase mimics, catalyzing the aerobic C-H oxidation of substituted aminophenols and diamines in aqueous media under air atmosphere. High-resolution mass spectrometry (HRMS) revealed key reaction intermediates, while electron paramagnetic resonance (EPR) confirmed the generation of radical species. Overall, this work reveals a rare example of methanol-triggered, in situ exfoliation of a bimetallic MOF into monolayer nanosheets, offering a powerful strategy to significantly improve oxidase-like activity from intact bulk MOFs.