Nanocage-Based Tb³⁺-Organic Framework for Efficiently Catalyzing the Cycloaddition Reaction of CO₂ with Epoxides and...

The catalytic performance of metal-organic framework (MOF)-based catalysts can be enhanced by increasing their catalytic sites, which prompts us to explore the multicore cluster-based skeletons by using designed functional ligands. Herein, the exquisite combination of [Tb₄(μ₂-OH)₂(CO₂)₈] cluster and 2,6-bis(2,4-dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (H₅BDCP) ligand generated a highly robust nanoporous framework of {[Tb₄(BDCP)₂(μ₂-OH)₂]·3DMF·5H₂O} (NUC-58), in which each four {Tb₄} clusters are woven together to generate an elliptical nanocage (aperature ca. 12.4 Å). As far as we know, NUC-58 is an excellent nanocage-cluster-based {Tb₄}-organic framework with the outstanding confined pore environments of a large specific surface area, high porosity, and plentiful coexisting Lewis acid-base sites of Tb³⁺, μ₂-OH and N_pyridine atoms. Performed experiments exhibited that NUC-58 owns a better catalytic performance for the cycloaddition reactions under mild conditions with a high turnover number and turnover frequency. Furthermore, NUC-58, as an eminent heterogeneous catalyst, can enormously boost the Knoevenagel condensation reactions. Thus, this work opens a path for the precise design of polynuclear metal cluster-based MOFs with excellent catalysis, stability, and regenerative behavior.