Multiple Ways Realizing Charge-State Transform in Au-Cu Bimetallic Nanoclusters with Atomic Precision

Abstract

Thiolate-protected nanoclusters with different charge states usually show similar structure frameworks but different electronic configurations, which are proved to dramatically affect their properties such as magnetism, photoluminescence, and catalytic activity. Until now, few nanoclusters with alterable charge states have been reported and only some of them are structurally solved, limiting the in-depth studies on their interesting properties. Here, a new Au-Cu alloy nanocluster [Au18Cu32(SPhCl)(36)](2-) (HSPhCl = 4-chlorophenylthiophenol) is synthesized and structurally solved by X-ray crystallography. Interestingly, it is found that this nanocluster can be reduced to another nanocluster with a different charge state, that is, [Au18Cu32(SPhCl)(36)](3-). This change in charge states is clearly proved by X-ray crystallography, electrospray ionization mass spectrometry, thermogravimetric analysis, and electron paramagnetic resonance. Furthermore, several redox methods are carried out to realize the reversible interconversion between these two nanoclusters, including electrochemical redox, introduction of H2O2/NaBH4, and oxidation with silica under air atmosphere. This work offers new insight into the transform progress of charge states with Au-Cu alloy nanoclusters which contributes to the understanding of the relationship between electronic structure and properties of nanoclusters and further development of Au-Cu nanoclusters with excellent performance.