Solvent‐Induced Reverse‐Ostwald Ripening: Structure Conversion from Ag 56 to Ag 45 Clusters and Its Impact on Catalytic Reduction of 4‐Nitrophenol

Controlled structure transformation in metal clusters is crucial for accessing novel architectures and understanding their structure-property correlations. Herein, we report a solvent-induced reverse-Ostwald ripening process between two atomically precise silver clusters, Ag₅₆ and Ag₄₅, which exhibit solvent-dependent structure variation: Ag₅₆ remains stable in dichloromethane, whereas exposure to pentane induces conversion to Ag₄₅. The compositions and structures of both clusters were determined by electrospray ionization mass spectrometry (ESI-MS) and single-crystal X-ray diffraction (SXRD). Structure analysis indicates that the Ag₄₅ forms via fragmentation and reorganization of the Ag₅₆ framework, distinct from the conventional Ostwald ripening observed in larger nano-systems. Although Ag₄₅ and Ag₅₆ share certain structural similarities, Ag₄₅ exhibits superior stability and higher catalytic activity for the reduction of 4-nitrophenol (4-NP) than Ag₅₆. Density functional theory (DFT) calculations further elucidate the catalytic reduction pathway on Ag₄₅. This work demonstrates a solvent-mediated reverse-Ostwald ripening pathway in silver clusters, providing atomic-level insights into active site construction and offering a blueprint for designing robust, cluster-based catalysts.