Enhancing the Stability and Catalytic Performance of Gold Subnanoclusters Mediated by Au···H-C Hydrogen Bonding and Au···π Interactions.

Gold subnanoclusters (AuSNCs) exhibit remarkable catalytic activity; however, their short-lived transient existence and strong tendency for self-aggregation remain disadvantageous for practical application. Considering that weak secondary interactions, such as Au···H-C or Au···π, could enhance the stability of the subnanocluster system, we have assessed their influence on the stabilization through a combination of experimental and computational analyses. We have evaluated the stabilization ability of different functional groups toward the AuSNCs system. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) experiments, density functional theory (DFT) calculations, and topological tools (QTAIM and NCI) provide decisive insights into the mechanism of stabilization of the short-lived AuSNCs species. Additionally, we extended the stabilization analysis to an application in catalysis. By conducting a complete NCI analysis of an optimized energy pathway, we demonstrate how an Au subnanocluster can be stabilized by a series of weak secondary interactions, including hydrogen bonds to gold (Au···H-C) as well as Au···π interactions in intermediates and transition states.