Hydrogen‐Bonding Assembly Meets Anion Coordination Chemistry: Framework Shaping and Polarity Tuning for Xenon/Krypton Separation

Abstract

AbstractHybrid hydrogen‐bonded (H‐bonded) frameworks built from charged components or metallotectons offer diverse guest‐framework interactions for target‐specific separations. We present here a study to systematically explore the coordination chemistry of monovalent halide anions, i.e., F−, Cl−, Br−, and I−, with the aim to develop hybrid H‐bond synthons that enable the controllable construction of microporous H‐bonded frameworks exhibiting fine‐tunable surface polarity within the adaptive cavities for realistic xenon/krypton (Xe/Kr) separation. The spherical halide anions, especially Cl−, Br−, and I−, are found to readily participate in the charge‐assisted H‐bonding assembly with well‐defined coordination behaviors, resulting in robust frameworks bearing open halide anions within the distinctive 1D pore channels. The activated frameworks show preferential binding towards Xe (IAST Xe/Kr selectivity ca. 10.5) because of the enhanced polarizability and the pore confinement effect. Specifically, dynamic column Xe/Kr separation with a record‐high separation factor (SF=7.0) among H‐bonded frameworks was achieved, facilitating an efficient Xe/Kr separation in dilute, CO2‐containing gas streams exactly mimicking the off‐gas of spent nuclear fuel (SNF) reprocessing.