Alloying and dealloying of Au18Cu32 nanoclusters at precise locations via controlling the electronegativity of substituent groups on thiol ligands

Abstract

The doping site of metals in an alloy nanocluster plays a key role in determining the cluster properties. Herein, we found that alloying engineering was achieved by replacing Cu at specific positions in the second layer Cu₂₀ shell of the [Au₁₈Cu₃₂(SR–O)₃₆]²⁻ or [Au₁₈Cu₃₂(SR–F)₃₆]³⁻ (SR–O = –S–PhOMe; SR–F = –SC₆H₃^3,4F₂) nanocluster with Au to generate a core–shell [Au_20.31Cu_29.69(SR–O)₃₆]²⁻ protected by mercaptan ligands with electron-donating substituents, which could be stable obtained compared with the alloyed nanocluster with electron-withdrawing substituent ligands. Moreover, dealloying engineering was accomplished by an electron-withdrawing substituent ligand exchange strategy (i.e., [Au₁₈Cu₃₂(SR–F)₃₆]²⁻). The abovementioned reaction was analyzed using single-crystal X-ray crystallography, electrospray ionization mass spectrometry, and X-ray photoelectron spectroscopy and monitored via time-dependent ultraviolet-visible absorption spectroscopy. This reversible and precise location of alloying and dealloying provides the possibility for studying the relationship between the structure and properties of nanoclusters at the atomic level.