Accompanied by the single-electron redox reactions, the phenylethanethiol-protected Au25-, Au250, and Au25+ nanoclusters can be reciprocally transformed with maintained structure. Taking the intramolecular cascade reaction on 2-nitrobenzonitrile for example, 2-nitrobenzonitrile is capable of capturing an electron from Au25-, which forms a free radical and further initiates the free radical reaction. Electron spin-resonance (ESR) spectra are employed to capture the signals of free radicals. In turn, excess NaBH4 provides hydrogen source to reduce the 2-nitrobenzonitrile into 2-amniobenzamide, and further return Au25 to the negative state. It should be noted that the Au25 nanoclusters would not structurally change in this recycle system, but just function as an electron bridge to transfer the electron consistently. Furthermore, the Au25- nanocluster protected by selenophenol has been successfully obtained, which exhibits superiorly catalytic activity in reducing the p-nitrophenol. Moreover, doping the single Cd heteroatom to the Au25(SC2H4Ph)18- nanocluster would significantly promote the efficiency in the oxidation of benzyl alcohol. On this basis, the synergistic effect between different metals in alloy nanoclusters has been precisely analyzed. Through analyzing the catalytic activity and selectivity on styrene propelled by Au-Ag bi-metallic nanoclusters, we conclude the catalytic role of Au, the selective role of Ag in the catalysis, and more obvious synergetic effect of surface-doped nanoclusters relative to nanoclusters with core-shell configuration. More importantly, the selectivity in oxidizing the styrene could be tailored by controlling the H2O adsorption on the surface of nanoclusters. In addition, substituting the central atom of the Ag25(SPhMe2)18- nanocluster with another metal atom (i.e., Pd, Pt, or Au) can remarkably influence the optical and electrochemical properties. Above-mentioned results provide atom-level insights into the essence of catalysis induced by ultra-small nanoparticles.

Organic reaction catalysed by atomically precise metal nanoclusters

256th National Meeting (2018)

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