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.