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Small: bonding mechanism of thiol ligands on gold clusters

wallpapers News 2020-12-09

gold clusters are widely used in nano medicine nano catalysis nano optics other fields because of their optical properties catalytic properties. However due to the structural heterogeneity of gold nanoclusters how to accurately control the size structure of gold nanoclusters in atomic accuracy then control their properties is the key to research. In recent years with the rapid development of experimental technology using sulfhydryl ligs to accurately control the size structure of gold nanoclusters has become a hot research direction. But experimentally the field is still in the "trial error" stage. People's understing of this kind of gold cluster structure mainly stays in the internal gold core lack of research on the structure bonding mechanism of surface sulfhydryl lig the interaction between gold core sulfhydryl lig. Specifically why can s-au-s in sulfhydryl ligs maintain a nearly linear structure based on the complex diverse core structures of gold clusters? There is only one 6S1 electron in the outermost layer of the Au atom. How can the Au atom form two Au-S covalent bonds in the sulfhydryl lig at the same time? These basic problems that need to be explained hinder the understing of the evolution of the structure properties of sulfhydryl lig protected gold clusters.

Dr. Wang Endong of Shanghai Institute of Applied Physics Chinese Academy of Sciences cooperated with Professor Xu Wenwu of Ningbo University researcher Gao Yi of Shanghai Institute of higher learning Chinese Academy of Sciences Dr. Zhu Beien etc. by introducing the 3-center-4 electron model combining with valence layer electron pair repulsion theory valence bond theory the structural characteristics special bonding mechanism of sulfhydryl ligs were explained. It is found that the Au atom in the sulfhydryl lig belongs to the super coordinated Au atom. The repulsion between the two pairs of bonding electrons (i.e. four bonding electrons) surrounding each Au atom in the lig makes the structure of each three atom Center (i.e. s-au-s) basically maintain a quasi linear structure. Based on the valence bond theory the bonding mechanism between the thiol ligs in real clusters the inner gold core surface is analyzed. The results show that the thiol ligs in real clusters can be regarded as a group of resonant structures. In each resonance structure the end s Atom on one side forms a normal Au-S covalent bond with the inner gold core the end s Atom on the other side forms a coordinated Au-S covalent bond with the inner gold core. Therefore the first mock exam is needed for each thiol lig to interact with the inner gold core. Considering the resonance structure the Au atom of each inner gold core surface contributes 0.5 electrons to the terminal S atom of each thiol lig which is a unified model of our group's previously explained lig stability for protection of gold clusters (Gr Unified). Model). The work of

provides a basic chemical picture of the bonding mechanism for protecting the sulfhydryl structure of the inner gold core which is helpful for the "bottom-up" theoretical design experimental preparation of clusters in the future. The results were published in

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