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

Abstract

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 Au₃ 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.