Mechanistic insights into Ag⁺ induced size-growth from [Au₆(DPPP)₄]²⁺ to [Au₇(DPPP)₄]²⁺ clusters

The size conversion of atomically precise metal nanoclusters lays the foundation to elucidate the inherent structure-activity correlations on the nanometer scale. Herein, the mechanism of the Ag⁺-induced size growth from [Au₆(dppp)₄]²⁺ to [Au₇(dppp)₄]³⁺ (dppp is short for 1,3-bis(diphenylphosphino)propane) is studied via density functional theory (DFT) calculations. In the absence of extra Au sources, the one "Au⁺" addition was found to be regulated by the Ag⁺ doping induced Au-activation, i.e., the formation of formal Au(i) blocks via the Ag⁺ alloying processes. The Au(i) blocks could be extruded from the core structure in the formed Au-Ag alloy clusters, triggering a facile Au⁺ migration to the Au₆ precursor to form the Au₇ product. This study sheds light on the structural and stability changes of gold nanoclusters upon the addition of Ag⁺ and will hopefully benefit the development of more metal ion-induced size-conversion of metal nanoclusters.