Nanocage-Based Tb 3+ -Organic Framework for Efficiently Catalyzing the Cycloaddition Reaction of CO 2 with Epoxides and Knoevenagel Condensation.

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 [Tb 4 (μ 2 -OH) 2 (CO 2 ) 8 ] cluster and 2,6-bis(2,4-dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (H 5 BDCP) ligand generated a highly robust nanoporous framework of {[Tb 4 (BDCP) 2 (μ 2 -OH) 2 ]·3DMF·5H 2 O} n ( NUC-58 ), in which each four {Tb 4 } 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 {Tb 4 }-organic framework with the outstanding confined pore environments of a large specific surface area, high porosity, and plentiful coexisting Lewis acid-base sites of Tb 3+ , μ 2 -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.