Fabrication of Pillar-Cage Fluorinated Anion Pillared Metal-Organic Frameworks via a Pillar Embedding Strategy and...

Flue gas desulfurization is crucial for both human health and ecological environments. However, developing efficient SO₂ 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 [NbOF₅ ]^2- and [TaOF₅ ]^2- anions acting as pillars. The APMOFs exhibits high porosity and density of fluorinated anions, ensuring exceptional SO₂ adsorption capacity and ultrahigh selectivity for SO₂ /CO₂ and SO₂ /N₂ gas mixtures. Furthermore, these two structures demonstrate excellent stability towards water, acid/alkali, and SO₂ adsorption. Cycle dynamic breakthrough experiments confirm the excellent separation performance of SO₂ /CO₂ gas mixtures and their cyclic stability. SO₂ -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 SO₂ molecules. The multiple-site host-guest and guest-guest interactions facilitate selective recognition and dense packing of SO₂ in this hybrid porous material. This work will be instructive for designing porous materials for flue gas desulfurization and other gas-purification processes.