MultivariateMetal–Organic Cages for EfficientC₂H₂/CO₂ Separation

Abstract

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.