The structural conversion of metal clusters leads to changes in their properties. Since these properties are structure-dependent, manipulating the structure conversion of metal clusters provides a pathway to explore their characteristics and potential applications. Typically, the structural transformation of metal clusters can be triggered by external stimuli such as ligands, temperature, light, pH, and solvent. Although significant progress has been made in studying the transformation of gold clusters under these stimuli, cases of structural transformation in silver clusters remain limited; moreover, silver clusters with reversible interconversion features are particularly rare and scarcely reported. This scarcity may be attributed to two primary reasons: (i) silver clusters exhibit higher chemical activity compared to gold clusters, making them prone to aggregation into large nanoparticles during harsh transformation processes, and (ii) the stability of Ag-S bonds in typical thiol-silver clusters presents a significant challenge for achieving reversible interconversion.
Recently, FNU Yao Chuanhao’s research team at the Strait Institute of Flexible Electronics (Future Technology) has made significant progress. They synthesized two types of silver clusters, Ag2 and Ag6, and revealed an intriguing solvent-driven reversible transformation between them. While both Ag2 and Ag6 display excellent photoluminescence properties, Ag2 demonstrates superior performance in X-ray radioluminescence compared to Ag6. Flexible scintillator films fabricated from Ag2 clusters exhibit outstanding X-ray imaging capabilities, achieving a spatial resolution of 15.0 lp/mm and a detection limit for an X-ray dose of 0.58 μGy s-1. This detection limit is nearly 10 times lower than the typical dose rate used in X-ray diagnostics (5.5 μGy s-1). The scintillator films incorporating Ag2 are expected to significantly reduce the radiation dose during X-ray diagnostics (e.g., CT), thus enhancing patient safety. This work not only confirms that solvent serves as an effective inducer for triggering the reversible transformation of silver clusters but also opens up a new avenue for developing silver cluster emitters for applications in X-ray imaging and detection. Relevant work, entitled “Reversible Interconversion between Ag2 and Ag6 Clusters and Their Responsive Optical Properties,” has been published in the top internationally renowned journal Journal of the American Chemical Society.
FNU is the primary affiliation of the research, with Xiang Huixin, a doctoral student at the Strait Institute of Flexible Electronics (Future Technology) of FNU and the Institute of Flexible Electronics (IFE) of Northwestern Polytechnical University (NWPU), Wang Yanze, a doctoral student at the Institute of Flexible Electronics of NWPU, and Xu Xinqi, a master's student at the College of Chemistry of Fuzhou University (FZU), as the co-first authors of the paper. Professor Yao Chuanhao of the Strait Institute of Flexible Electronics (Future Technology) and Professor Liu Xiaowang of NWPU are the co-corresponding authors. This work was supported by start-up research funding from Fujian Normal University and the National Natural Science Foundation of China.
Translated by Liao Xuehe / Reviewed by Yang Li