Engineering Steric-Hindrance-Guided Crystalline Vacancies in a Scalable Pillared-Layer Nickel-MOF for Efficient Gas Uptake and Separation

Engineering local vacancies in metal-organic frameworks (MOFs) presents a promising route to high-performance gas adsorption/separation, yet conventional defect engineering often yields statistically distributed vacancies. Here, we report a steric-hindrance-programmed strategy to construct periodically ordered vacancies in pillared-layer LIFM-Ni-3-H₂O via de novo synthesis by changing pyrazine linkers in a full-pillared reference TJE-1 to bulkier triethylenediamine ligands, resulting in missing-pillars to produce potential vacancies in a regularly staggered interlayer fashion. Single-crystal x-ray diffraction unambiguously identifies the alternating pillar/vacancy arrangement, and digestion ¹H NMR supports overall stoichiometry. Removing capped water molecules converts LIFM-Ni-3-H₂O into LIFM-Ni-3 with complete exposure of the open-metal Ni²⁺-sites, reshaping the local pore to form a contracted Window-I and an enlarged Window-II bearing open-metal sites for molecular accessing and binding. LIFM-Ni-3 enables efficient separation processes: adsorbing SF₆ at Window-II with 2.64 mmol g^-1 uptake at 0.1 bar while excluding N₂, and purifying CH₄ by removing minor C₂H₆/C₃H₈ from natural gas with an exceptional productivity of 13.5 mmol g^-1. This represents a rare example that features simultaneously high capacity and selectivity by overcoming capacity-selectivity trade-off, and combines favorable low-pressure capture with fast apparent uptake responses. The scale-up experiment testifies reliability of this pillar-displacing approach for mass production and scalable gas separation.