25:T4ea,Efficient adsorption separation of xenon/krypton (Xe/Kr) mixtures is an important technological challenge due to their similar sizes and shapes. Herein, we report an ultramicroporous metal-organic framework (MOF), ZJU-Bao-302a, with pore sizes close to the kinetic diameter of Xe and pore surfaces lined with a high density of polar sites, including methyl groups, amines, and uncoordinated oxygen atoms. The synergistic effect of these polar sites enables ZJU-Bao-302a to exhibit a high Xe uptake of 2.77 mmol g^-1 and a balanced Xe/Kr selectivity of 14.6 under ambient conditions. Dynamic breakthrough experiments demonstrate the material's capability to efficiently separate Xe/Kr mixtures (20/80) as well as capture Xe at ultralow concentrations (400 ppmv) from nuclear reprocessing exhausts, achieving a superior dynamic Xe capacity of 24.2 mmol kg^-1. Density functional theory calculations reveal that the localized polar groups/atoms in ZJU-Bao-302a provide more effective recognition sites for Xe than Kr, enhancing the thermodynamic selectivity. This study highlights the importance of integrating tailored pore sizes and dense polar sites in metal-organic frameworks for developing high-performance Xe/Kr separation adsorbents.26:T520,The separation of xylene isomers, especially para-xylene, is a crucial but challenging process in the chemical industry due to their similar molecular dimensions. Here, a flexible metal-organic framework, Ni(ina)₂, (ina = isonicotinic acid) is employed to effectively discriminate xylene isomers. The adsorbent with adaptive deformation accommodates the shapes of isomer molecules, thereby translating their subtle shape differences into characteristic framework deformation energies. Through a combination of multiple local flexibility behaviors, Ni(ina)₂ exhibits guest-specific structural transformations that energetically favor para-xylene over other isomers. Single-crystal X-ray diffraction, in situ powder X-ray diffraction, and theoretical investigations validate this "adaptive fitting" mechanism, where the degree of structural deformation scales with the mismatch between the molecular shape and pore geometry. As a result, Ni(ina)₂ achieves exceptional para-xylene selectivity in both liquid and vapor phase separations, maintaining a high para-xylene purity and productivity. This work demonstrates a novel strategy of exploiting framework flexibility to address challenging molecular separations and provides fresh insights into the design of selective adsorbents.27:T544,The separation of octafluoropropane (C₃F₈) from hexafluoropropylene (C₃F₆) is an industrially important yet challenging process due to their similar physicochemical properties and stringent purity demands in industrial applications. Herein, we address this task through precise pore architecture in a zirconium-based metal-organic framework (Zr-PMA), which exhibits unique "wiggling nanopores" with narrow windows and large cavities. The narrow windows act as diffusion barriers, selectively restricting C₃F₈ transport, while the large cavities provide strong adsorption sites for C₃F₆, enabling an equilibrium-kinetic synergistic separation. This dual functionality results in a ∼450-fold difference in diffusion rates and exceptional kinetic selectivity for C₃F₆ over C₃F₈, as demonstrated by adsorption isotherms, time-resolved kinetics, and dynamic breakthrough experiments. Theoretical calculations coupled with in situ spectroscopy elucidate the pore geometry-dependent hopping diffusion mechanism responsible for the separation. This work establishes wiggling pore geometry as a versatile paradigm for advanced adsorbents targeting energy-efficient separations of structurally similar fluorocarbon mixtures.

	Year	Citations

About