Exploring the Effect of Different Secondary Building Units as Lewis Acid Sites in MOF Materials for the CO2 Cycloaddition Reaction

In order to explore the catalytic effect of differentLewis acidsites (LASs) in the CO2 cycloaddition reaction, differentsecondary building units and N-rich organic ligand 4,4 & PRIME;,4 & DPRIME;-s-triazine-1,3,5-triyltri-p-aminobenzoatewere assembled to construct six reported MOF materials: [Cu-3(tatab)(2)(H2O)(3)]& BULL;8DMF & BULL;9H(2)O (1), [Cu-3(tatab)(2)(H2O)(3)]& BULL;7.5H(2)O (2), [Zn4O(tatab)(2)]& BULL;3H(2)O & BULL;17DMF (3), [In3O(tatab)(2)(H2O)(3)](NO3)& BULL;15DMA (4), [Zr6O4(OH)(7)(tatab)(Htatab)(3)(H2O)(3)]& BULL;xGuest (5), and[Zr6O4(OH)(4)(tatab)(4)(H2O)(3)]& BULL;xGuest (6) (DMF = N,N-dimethylformamide,and DMA = N,N-dimethylacetamide).Large pore sizes of compound 2 enhance the concentrationof substrates, and the multi-active sites inside its framework synergisticallypromote the process of the CO2 cycloaddition reaction.Such advantages endow compound 2 with the best catalyticperformance among the six compounds and surpass many of the reportedMOF-based catalysts. Meanwhile, the comparison of the catalytic efficiencyindicated that Cu-paddlewheel and Zn4O display better catalyticperformances than In3O and Zr-6 cluster. Theexperiments investigate the catalytic effects of LAS types and provethat it is feasible to improve CO2 fixation property byintroducing multi-active sites into MOFs. Different secondary building units andN-rich ligands wereassembled to construct MOFs with multi-active sites. The effect andcomparison among different Lewis acid site types in CO2 cycloaddition reactions were investigated through series of experiments.

Automated summary

Different secondary building units and N-rich organic ligand 4,4 & PRIME;,4 & DPRIME;-s-triazine-1,3,5-triyltri-p-aminobenzoate were assembled to construct six MOF materials and investigate the catalytic effects of different Lewis acid sites in the CO2 cycloaddition reaction. Compound 2, with larger pore sizes and multiple active sites, showed the best catalytic performance among the six compounds and outperformed many reported MOF-based catalysts. The comparison also revealed that Cu-paddlewheel and Zn4O exhibited better catalytic performances than In3O and Zr-6 cluster.