For pure acetylene manufacturing and natural gas purification, the development of porous materials displaying highly selective C 2 H 2 /CH 4 and CO 2 /CH 4 separation is greatly important but remains a major challenge. In this work, a plausible strategy involving solvent-induced effects and using the flexibility of the ligand conformation to make two In(III) metal−organic frameworks (MOFs) is developed, showing topological diversity and different stability. The X-shaped tetracarboxylic ligand H 4 TPTA ([1,1′:3′,1″-terphenyl]-4,4′,4″,6′-tetracarboxylic acid) was selected to construct two new heteroid In MOFs, namely, {[showing a pts topology with a large channel that is not conducive to fine gas separation. By contrast, with the reduction of SBU from uninucleated In to an {In-OH-In} n chain, MOF 2 has a (4, 6)connected net with the fsc topology with an ∼5 Å suitable micropore to confine matching small gas. The permanent porosity of MOF 2 leads to the preferential adsorption of C 2 H 2 over CO 2 with superior C 2 H 2 /CH 4 (332.3) and CO 2 /CH 4 (31.2) separation selectivities. Meanwhile, the cycling dynamic breakthrough experiments showed that the high-purity C 2 H 2 (>99.8%) capture capacities of MOF 2 were >1.92 mmol g −1 from a binary C 2 H 2 /CH 4 mixture, and its separation factor reached 10.

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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, 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.

Acetylene is an important industrial gas for the production of vinyl chloride and 1,4-butynediol, but its storage remains a major challenge because it is highly explosive. Flexible metal–organic frameworks (FMOFs) are always at the forefront of porous materials due to the transformation of the structure under the external stimuli. In this work, divalent metal ions and multifunctional aromatic N,O-donor ligands were chosen, and three FMOFs [M­(DTTA)2]·guest [M = Mn (1), Cd (2), and Cu (3)] (H2DTTA = 2,5-bis­(1H-1,2,4-trazol-1-yl) terephthalic acid) have been successfully constructed. Single-crystal X-ray diffractions show that these compounds are isostructural and feature a three-dimensional framework. Topological analysis shows a (4, 6)-connected network with a Schläfli symbol of {44.610.8}­{44.62}. All three compounds exhibit breathing behavior on N2 adsorption at 77 K, and due to the difference of ligand torsion angles, compounds 2 and 3 exhibit extraordinary adsorptions for C2H2 of 101 and 122 cm3 g–1 at 273 K under 1 bar, respectively. Compared with previous work, successfully obtaining compound 3 with an innovative structure can be attributed to the solvent-induced effect in the process of crystal synthesis, leading to the structure transformation promoting the significantly increased C2H2 adsorption performance. This study provides a platform for improvement of synthetic structures, which can effectively boost gas adsorption performance.

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