Low-Dimensional Silver(I) Coordination Polymers Based on a Flexible Dithione Ligand: Anion-Dependent Structures and...

The capture and immobilization of radioactive iodine remain significant challenges due to its high volatility and radiotoxicity. Herein, we report a series of five low-dimensional, nonporous Ag(I) coordination polymers based on a methimazole-derived sulfur-donor ligand, designed to investigate the role of coordinated anions in iodine adsorption. The compounds were synthesized via a controlled branched-tube method and structurally characterized by single-crystal X-ray diffraction, revealing one- and two-dimensional architectures depending on the coordinated anion (NO3-, Cl-, I-, SCN-, and N3-). Iodine uptake was systematically evaluated in both the vapor and solution phases. Despite the absence of permanent porosity, all materials exhibit substantial iodine adsorption, with the azide-containing polymer (CP-5) showing the highest uptake (up to 4171 mg g-1 in solution and 545 wt % in the vapor phase). A clear dependence of adsorption performance on the coordinated anion was observed (NO3- < Cl- < I- < SCN- < N3-), indicating that anion-dependent electronic properties contribute to iodine affinity. Postadsorption PXRD and Raman analyses reveal distinct iodine capture pathways across the series: the nitrate-containing framework undergoes partial transformation to AgI, whereas the remaining coordination polymers retain their structural integrity and stabilize iodine predominantly as polyiodide species. These findings demonstrate that iodine uptake in nonporous Ag(I) coordination polymers is governed primarily by anion-dependent stabilization of iodine species and charge-transfer interactions rather than by porosity alone, highlighting anion selection as an effective strategy for tuning iodine capture performance.