Modulator-Dependent Dynamics Synergistically Enabled Record SO₂ Uptake in Zr(IV) Metal-Organic Frameworks Based on Pyrene-Cored Molecular Quadripod Ligand

Developing innovative porous solid sorbents for the capture and storage of toxic SO₂ is crucial for energy-efficient transportation and subsequent processing. Nonetheless, the quest for high-performance SO₂ sorbents, characterized by exceptional uptake capacity, minimal regeneration energy requirements, and outstanding recyclability under ambient conditions, remains a significant challenge. In this study, we present the design of a unique tertiary amine-embedded, pyrene-based quadripod-shaped ligand. This ligand is then assembled into a highly porous Zr-metal-organic framework (MOF) denoted as Zr-TPA, which exhibits a newly discovered 3,4,8-c woy net structure. Remarkably, our Zr-TPA MOF achieved an unprecedented SO₂ sorption capacity of 22.7 mmol g^-1 at 298 K and 1 bar, surpassing those of all previously reported solid sorbents. We elucidated the distinct SO₂ sorption behaviors observed in isostructural Zr-TPA variants synthesized with different capping modulators (formate, acetate, benzoate, and trifluoroacetate, abbreviated as FA, HAc, BA, and TFA, respectively) through computational analyses. These analyses revealed unexpected SO₂-induced modulator-node dynamics, resulting in transient chemisorption that enhanced synergistic SO₂ sorption. Additionally, we conducted a proof-of-concept experiment demonstrating that the captured SO₂ in Zr-TPA-FA can be converted in situ into a valuable pharmaceutical intermediate known as aryl N-aminosulfonamide, with a high yield and excellent recyclability. This highlights the potential of robust Zr-MOFs for storing SO₂ in catalytic applications. In summary, this work contributes significantly to the development of efficient SO₂ solid sorbents and advances our understanding of the molecular mechanisms underlying SO₂ sorption in Zr-MOF materials.