Strictly Periodic, Adenine-Directed One-Pot Assembly of Multicomponent Metal-Organic Framework: Structural Insights...

The pursuit of advanced adsorbents with exceptional gas adsorption and separation capability represents a highly promising yet challenging research frontier. Several quinary multicomponent metal-organic frameworks (MOFs) have been documented in the literature, however, the construction of quinary MOFs through the synergistic integration of two distinct organic ligands and three different metal clusters remains scarce. Herein, solvothermal reaction of Zn(OAc)₂·2H₂O with adenine and 1,2,4-benzenetricarboxylic anhydride afforded a novel MOF of Quin-Zn-Ad-BTC. SCXRD reveals that Quin-Zn-Ad-BTC incorporates three distinct zinc-based structural units of a mononuclear [ZnN₂(O₂C─)₂], a dinuclear [Zn₂(Ad)₃(O₂C─)₂], and a hexanuclear [Zn₆N₃(μ-H₂O)₃(Ad)₃(O₂C─)₆], respectively. These units assemble into a novel quinary MOF structure, distinguished as the unusual material constructed from dual ligands and triple clusters. It features three interconnected cage-like cavities replete with uncoordinated carboxylate oxygen atoms and Watson─Crick sites. Gas adsorption investigations indicate that Quin-Zn-Ad-BTC demonstrates notable selectivity toward acetylene, ethane, and propylene adsorption, enabling the single-step ethylene purification from trinary C₂ mixtures and binary MTO products. Computational simulations reveal that preferential adsorptions are facilitated by different supramolecular interaction strengths. Given its cost-effective and readily accessible synthesis precursors, along with excellent thermal and chemical stability, Quin-Zn-Ad-BTC holds great promise for advanced gas adsorption and separation applications.