Interrogating the Metal Identity Effect of Isostructural NU-1801 Frameworks on Toxic Gas Capture with Moisture-Enhanced Feature

The effective capture of toxic industrial chemicals (TICs), particularly at low concentrations and under humid conditions, is essential for industrial chemical waste management and environmental hazard remediation. Among existing sorbents, metal–organic frameworks (MOFs) are promising materials for TIC capture, yet a significant gap remains in the design principles. Herein, we leveraged reticular chemistry to construct isostructural NU-1801 frameworks with Y6, Zr6, Hf6, Ce6, and Th6 clusters, providing a systematic platform to elucidate the structure–property relationships among metal identity, framework stability, and adsorption performance for TICs. Among the five analogs, NU-1801­(Zr) had the highest structural stability and adsorption performance for SO2 and NH3. Breakthrough experiments demonstrated that NU-1801­(Zr) exhibited moisture-enhanced behavior for SO2 and NH3 capture driven by the formation of sulfate and ammonium species, respectively. Molecular studies revealed that the binding pockets of SO2 and NH3 were located at the metal carboxylic cluster, with μ3–OH species serving as the main binding sites. Additionally, coadsorption binding geometries of H2O + SO2 and H2O + NH3 are more thermodynamically favorable than the formation of a pure H2O network, explaining the experimentally observed formation of sulfate and ammonia species. This work demonstrates the critical role of metal identity in the rational design of isostructural MOF adsorbents for practical TIC capture.