Solvent-Induced Reverse-Ostwald Ripening: Structure Conversion from Ag₅₆ to Ag₄₅ 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. © 2026 Wiley-VCH GmbH.