Size-Matching-Driven SF₆ Capture Via Isoreticular Pore Contraction in a Microporous MOF

Efficient capture of sulfur hexafluoride (SF₆) from dilute mixtures remains a critical challenge. Herein, we demonstrate a size-matching strategy via isoreticular pore contraction in a microporous MOF, where the pore aperture is reduced from ∼9 Å to ∼6 Å by ligand substitution. The resulting confined pore environment in Zn(NDC)(TED)₀.₅ acts as a molecular clamp for SF₆, leading to a nearly 4-fold enhancement in uptake, from 12 to 47 cm³ g^-1 at 0.1 bar, and a remarkable enhancement in SF₆/N₂ selectivity from 74 to 558. Enhanced adsorption enthalpy, IAST analysis, and breakthrough experiments confirm superior separation under dilute conditions, while GCMC simulations reveal localized adsorption within confined pockets. This work highlights pore contraction as an effective strategy for high-performance SF₆ capture.