Zeolitic Metal Cluster Carboxylic Framework for Selective Carbon Dioxide Chemical Fixation through the Superlarge Cage

Metal-organic frameworks (MOFs) with zeolitic structure process fantastic structural metrics and display excellent applications in many aspects; however, they are difficult to assemble. Herein, on the basis of a tetrahedral Zn₄O cluster and a 3,5-bis(2,4-dicarboxylphenyl)nitrobenzene (H₄L) ligand, a novel sodalite (SOD) zeolitic cluster framework (ZCF), {[Zn₄(O)(L)₂]·4DMF·6H₂O}_n (ZCF-1; DMF = N,N-dimethylformamide), has been hydrothermally synthesized. Compared with the traditional SOD zeolitic framework of ZIF-8, the cage size of ZCF-1 is dramatically improved from 16.9 to 29.2 Å by the introduction of longer tetradentate carboxylic ligands. Moreover, because of the functional nitryl group in the ligand, ZCF-1 exhibits a high CO₂/CH₄ selectivity. Hence, further research on the chemical fixation of CO₂ is implemented, which reveals excellent heterogeneous catalytic activity and durability. Especially, a unique selective catalytic performance with a high yield of 88.3% on a larger molecular size reactant (glycidyl phenyl ether) is observed, which is attributed to the stereoselection effect of the superlarge cage and abundant Zn₄O catalytic clusters in ZCF-1.