Nitrogen-Rich Tetrazole-Amide-Functionalised Zn Metal-Organic Framework as Catalyst for Efficient Catalytic CO₂ Cycloaddition with Epoxides

In this study, we report the design, synthesis, and catalytic application of the novel nitrogen-rich Zn(II) MOF [Zn-2(mu(3)-1 kappa N,2 kappa N ',3 kappa O-HL)(2)(DMF)(2)](n)nH(2)O (HL2- = 4-((4-(1H-tetrazol-5-yl)phenyl)carbamoyl)benzoate), denoted as ZnMOF, for the efficient conversion of carbon dioxide (CO2) to cyclic carbonates via cycloaddition with epoxides. It was synthesised from a tetrazole appended amide-functionalised pro-ligand (H3L) and Zn(NO3)(2)6H(2)O under hydrothermal conditions. The synthesised material was characterised namely by elemental analysis, infrared spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction analyses. The catalytic potential of ZnMOF was investigated in the CO2 cycloaddition reaction with various epoxides, with conversions ranging from 17% to 99%. The catalyst retained its activity across multiple reaction cycles, demonstrating its stability and reusability. The influence of co-catalysts on the reaction was explored, with tetrabutylammonium bromide (TBABr) emerging as the most effective one. A plausible reaction mechanism is proposed.