Programmed Pore Engineering in an Isoreticular Triazole–MOF Series for One‐Step Ethylene Separation

Abstract Ethylene (C 2 H 4 ) purification from CO 2 /C 2 H 2 /C 2 H 4 ternary mixtures is industrially crucial yet remains highly challenging. Current metal–organic frameworks (MOFs) lack the ideal CO 2 > C 2 H 2 > C 2 H 4 adsorption sequence necessary for stepwise removal of impurities. Herein, we address this gap through precise pore environment tuning within an isoreticular series of zinc–triazole MOFs. By modulating the number and position of ─NH 2 /─CH 3 groups on the ligand, we precisely control pore chemistry from one‐dimensional (1D) channels to two‐dimensional (2D) interconnected channels, which successfully achieves the targeted adsorption order. The unilateral amino groups in the optimized MOF, ZSTU‐30 , create unique supramolecular interlocking sites that strongly bind CO 2 while mitigating interactions with C 2 H 4 and C 2 H 2 . Consequently, ZSTU‐30 enables the direct production of polymer‐grade C 2 H 4 (> 99.9%) from a ternary gas mixture in a single step, with an exceptional C 2 H 4 productivity of 3.18 mmol g −1 . The CO 2 –host interaction mechanism is elucidated by in situ single‐crystal X‐ray diffraction and theoretical calculations, which reveal multiple supramolecular interactions at the adsorption sites. Combining excellent water and pH stability, ZSTU‐30 stands out as a robust and promising physisorbent for one‐step C 2 H 4 purification.