Two Water-Stable Silver–Sulfur MOFs with Interesting Topology: High-Performance H2S Adsorption and Record-Breaking Iodine Uptake

Sulfur-based coordination polymers have gained significant attention, yet constructing 3D sulfur-based networks remains challenging. This study presents two novel 3D water-stable silver-sulfur MOFs: {[Ag6Cl2(L3)5][BF4]4}n(SCU-1) and [AgSCN(L3)]n(SCU-2). Single crystals were synthesized using the branched tube method, and X-ray crystallography revealed SCU-1’s large cationic framework with 193 atoms per unit cell and a volume of ∼10,000 Å3, exhibiting 15.1% porosity. SCU-2, with a simpler structure, showed 5.9% porosity. Leveraging the strong silver-sulfur affinity and the methimazole-based ligands’ potential for iodine uptake, the iodine adsorption capabilities of SCU-1 and SCU-2 were investigated, revealing remarkable uptake capacities of 3.650 g/g and 3.749 g/g, respectively, setting a new benchmark for iodine removal. Additionally, the H2S adsorption potential of these frameworks was explored for the first time. SCU-1, with BF4-and Cl- as electron-rich sites, exhibited a higher H2S adsorption energy (Eads = −45.0 kJ mol-1) compared to SCU-2 (Eads = −39.0 kJ mol-1), where thiocyanate serves as the electron-rich component. Simulations aligned well with experimental data, highlighting the frameworks’ potential for gas adsorption applications. This work advances the design of sulfur-based MOFs for environmental remediation, particularly in iodine and H2S capture.