Improved pleiotropic antibacterial activity of Ag(I)-Thiolate coordination polymers via iodide encapsulation in multinuclear silver nano cages

Silver-based nanomaterials have attracted considerable attention due to their antimicrobial properties. In this study, two nano-Ag^I-cage-based coordination polymers, [Ag₆(<i>μ</i>-S<i>t</i>Bu)₆]_n (University of South China Coordination Polymer USC-CP-2) and [Ag₁₄(<i>μ</i>-S<i>t</i>Bu)₁₂I₂]_n (USC-CP-3), were synthesized via the reaction of AgNO₃ and 2-methyl-2-propanethiol (HS<i>t</i>Bu) with sodium ethylate as a non-toxic base in a water/ethanol mixed solvent, with and without iodide as a coligand. Structural analysis by single-crystal X-ray diffraction revealed that both polymers are one-dimensional Ag(I)-thiolate coordination polymers with distinct secondary building units: USC-CP-2 features Ag₆ nano-cages stabilized by μ₂-S<i>t</i>Bu ligands, while USC-CP-3 comprises nanochains formed by iodide-encapsulated Ag₁₆-cages linked through edge-sharing. Antimicrobial studies against <i>Escherichia coli</i> demonstrated that USC-CP-3, featuring iodide-encapsulated Ag₁₆-cages, exhibited superior antibacterial activity compared to the iodide-free Ag₆-cages in USC-CP-2. Mechanistic studies, supported by ICP-MS, EPR, TEM, and SEM analyses, suggested that the synergistic bactericidal effects arise from the release of Ag(I) ions, hydroxyl radical generation, and the presence of iodide. This study highlights a rational design strategy for advanced antibacterial materials with potential applications in combating bacterial contamination.