Significant Enhancement of Xe Adsorption and Xe/Kr Separation of Metal–Organic Framework Induced by Pore Channel Shaping and Pore Polarity Engineering

Developing porous solids possessing efficient Xe/Kr separation remains a challenging issue owing to the similarities in the physicochemical properties of Xe and Kr. Herein, chlorinated metal–organic framework (MOF) JXNU-20(Cl) and its parent JXNU-20 were rationally developed for Xe/Kr separation. Remarkably, the Xe uptake (5 mmol cm–3) and Xe/Kr separation selectivity (9.4) for JXNU-20(Cl) (298 K and 1 bar) are 2.6 and 2.7 times higher than those for JXNU-20, empowering JXNU-20(Cl) with efficient Xe/Kr separation performance. The incorporation of chlorine groups into JXNU-20(Cl) generates a greatly polar pore environment and strong pore confinement effect resulting from the bottleneck segments of channels. The significant performance improvement of JXNU-20(Cl) can be rationalized as the enhanced pore surface polarity and strong pore confinement effect offered by the chlorine substituents. An elaborately effective approach for shaping pore channels and tuning pore polarity of a MOF is developed for the separation of targeted gases with polarizability differences.