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-AgI-cage-based coordination polymers, [Ag6(μ-StBu)6]n (University of South China Coordination Polymer USC-CP-2) and [Ag14(μ-StBu)12I2]n (USC-CP-3), were synthesized via the reaction of AgNO3 and 2-methyl-2-propanethiol (HStBu) 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-StBu ligands, while USC-CP-3 comprises nanochains formed by iodide-encapsulated Ag16-cages linked through edge-sharing. Antimicrobial studies against Escherichia coli 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.