Abstract
The recent progress in atomically precise metal (Au, Ag etc.) nanoclusters has greatly enriched the molecular-level mechanistic understanding of metal nanomaterials. Herein, using two meta-stable (easy formation, easy transformation) clusters, i.e. [Au(23)SCy(16)](-) and [Au(6)(dppp)(4)](2+) (HSCy and dppp denote cyclohexanethiol and 1,3-bis(diphenylphosphino)propane), as the reaction precursors, the etching of Au(23) occurs smoothly, giving the one/two-atom size-reduced [Au(21)SCy(12)(dppp)(2)](+) and [Au(22)SCy(14)(dppp)](2+) as the major products. Structural analysis and DFT calculations indicate that the active reaction site of Au(23) lies in the core-shell interference of the bi-capped icosahedral Au(15) core and the AuS(2) motifs. The fluorescence, band gap, and thermostability of the Au(21) cluster products are improved compared to that of the Au(23) precursors.