Two Stable Sodalite-Cage-Based MOFs for Highly Gas Selective Capture and Conversion in Cycloaddition Reaction

Stable metal–organic frameworks, containing periodically arranged nanosized cages or pores and active Lewis acid–base sites, are considered ideal candidates for efficient heterogeneous catalysis. Herein, based on the light of reticular chemistry design principles, the ingenious assembly of two pyridine N-rich multifunctional triangular linkers, H 3 TBA [3,5-di (1h-tetrazol-5-yl) benzoic acid] and H 2 TZI [5-(1H-tetrazol-5-yl)isophthalic acid], with Mn II formed PCP-33(Mn) and PCP-34(Mn), respectively. PCP-33(Mn) and PCP-34(Mn) are typical sod topology zeolitic metal–organic frameworks (ZMOFs) with hierarchical tetragonal micropores and metal organic polyhedral sodalite-like cages. The inner walls of these cages are modified by open metal sites Mn II and Lewis acid–base sites of halide ions and N pyridine atoms. The characteristics of the cages’ structures make two MOFs exhibit high surface area and a small window, which promote their outstanding gas capture ability (C 2 H 2, 131.8 cm 3 g –1; CO 2, 77.9 cm 3 g –1 at 273 K) and selective separation performance (C 2 H 2 /CH 4, 226.2, CO 2 /CH 4, 50.3 at 298 K), and are also suitable as catalytic reactors for metal/solvent-free chemical fixation of CO 2 with epoxides to achieve high-efficiency CO 2 conversion. Furthermore, they are greatly recyclable for several cycles while retaining their structural rigidity and catalytic activity.