Multivariate Metal–Organic Cages for Efficient C2H2/CO2 Separation

Multivariate metal–organic cages (MTV-MOCs) are multifunctional materials created by combining various organic ligands with different functional groups in a single structure. Under the guidance of reticular chemistry, we selected six ligands with identical main bodies but different functional groups [BDC-X, BDC = 1,4-benzenedicarboxylic acid, X = ethenyl (A), NH2 (B), alkyne (C), Cl (D), F (E), and allyl (F)] and successfully constructed nine reticular MTV-MOCs. The optimized ZrT-1-AABBCD exhibited the best C2H2/CO2 (50/50) separation performance. Both ideal adsorbed solution theory (IAST) selectivity (increased by 88.5%) and separation efficiency (increased by 375%) were significantly improved, compared to those of ZrT-1-ethenyl. Both experiments and theoretical simulations verified the synergistic mechanism of multifunctional groups and the excellent performance of this material system in C2H2/CO2/CH4 multicomponent gas separation. ZrT-1-AABBCD can also directly purify C2H2 in liquid solutions. This work provides theoretical guidance for the design of crystalline multivariate porous materials for gas separation.