Fabrication of Pillar‐Cage Fluorinated Anion Pillared Metal–Organic Frameworks via a Pillar Embedding Strategy and Efficient Separation of SO 2 through Multi‐Site Trapping

Flue gas desulfurization is crucial for both human health and ecological environments. However, developing efficient SO 2 adsorbents that can break the trade‐off between adsorption capacity and selectivity is still challenging. In this work, a new type of fluorinated anion‐pillared metal–organic frameworks (APMOFs) with a pillar‐cage structure is fabricated through pillar‐embedding into a highly porous and robust framework. This type of APMOFs comprises smaller tetrahedral cages and larger icosahedral cages interconnected by embedded [NbOF 5 ] 2− and [TaOF 5 ] 2− anions acting as pillars. The APMOFs exhibits high porosity and density of fluorinated anions, ensuring exceptional SO 2 adsorption capacity and ultrahigh selectivity for SO 2 /CO 2 and SO 2 /N 2 gas mixtures. Furthermore, these two structures demonstrate excellent stability towards water, acid/alkali, and SO 2 adsorption. Cycle dynamic breakthrough experiments confirm the excellent separation performance of SO 2 /CO 2 gas mixtures and their cyclic stability. SO 2 ‐loaded single‐crystal X‐ray diffraction, Grand canonical Monte Carlo (GCMC) simulations combined with density functional theory (DFT) calculations reveal the preferred adsorption domains for SO 2 molecules. The multiple‐site host–guest and guest‐guest interactions facilitate selective recognition and dense packing of SO 2 in this hybrid porous material. This work will be instructive for designing porous materials for flue gas desulfurization and other gas‐purification processes.