Synthesis And Characterization Of Au₃₆（SCH₂Ph-^tBu）₈Cl₂₀ And Au₂₄（SePh-^tBu）₂₀

In the history of human development, gold are wide welcome because of its rarity and chemical stability. In recent years, it was found that gold particles in nano size show very different chemical and physical properties from bulk gold. when the gold particles in nano size, with the change of the size, the gold nanoparticles will have different optical properties (like:uv, fluorescence, etc.), different catalytic properties(different conversion and different selectivity, etc.) and different electrochemical properties(the different electrochemical Oxidation ability and the different reduction ability). Based on the understanding of the properties of the gold nanoparticles which are in nano size, scientists are beginning to focus on gold nanomaterials, they think that the properties of the gold nanoparticles on the nanoscale will get very good application. In 1994, Brust and his colleagues first using bipolar method (oil phase and water phase) synthesis of gold nanoparticles, depend on this size focus synthetic methods, the accurate atomic number of gold nanoparticles were synthesized. But there have many problems, the challenges of the clusters synthesis is that the clusters are not controlled. In 2008, Professor Manzhou Zhu put forward dynamics control synthesis gold clusters which achieve the controllable synthesis of gold clusters. Then the gold nano clusters gradually being synthesized. As the improvement of nano material testing conditions, a growing number of clusters were characterized. Because the gold nano clusters are difficult to crystallization, so the protection of mercaptan gold nano clusters structure has not been characterized, the structure of mercaptan protection gold nanoparticles has always been a mystery. For the exploration of the unknown, scientific research workers never give up. In 2008, Jadzinsky group reported the first gold nano clusters Au102 which protected by mercaptan. It’s more established the scientific research workers’confidence by characterization of mercaptan protection gold nano clusters structure of Au102. Then, a lot of gold nano clusters has been characterized structure. Because of a large amount of thiol protection gold nano clusters’structure is characterized. Scientists exploring gold nano clusters to determine the structure of properties. Catalytic and optical properties have been as the main research direction of the property of the gold nano clusters.Based on the predecessors’ a lot of experimental, we try to synthesis small molecules as the ligands to protect golden nano clusters which used to study its catalytic performance. We used dynamics method which is adopted to control the clusters by changing the types of weak reductant. In result, we synthesis and crystal structure of a new Au36(SCH2Ph-tBu)8Cl20 nanocluster (Au36-Cl for short). The structure of the Au36-Cl comprises a Au14 inner core with two Cl atoms, a pair of pentameric Au5(SCl5) staple motifs, and a pair of hexamer Au6(S3Cl4) motifs. Compared with the Au36(SR)24 nanocluster previously reported by the Jin group, the Au36-Cl nanocluster shows four distinct di erences:(a) eight free electrons; (b) dissimilar optical properties; (c) a Au14 core consisting of two Au7 units; and (d) unique "AunClm" staple motifs, which is observed for the first time in thiolate protected gold nanoclusters. (The Cl atoms have been analyzed by X-ray photoelectron spectroscopy.1. This study presents a new crystal structure of a gold nanocluster coprotected by thiolate and chloride, with the formula of Au36(SCH2Ph-tBu)8Cl20. This nano-cluster is composed of a Au14 core with two Cl atoms, a pair of pentameric Au5(SCl5) staple motifs, and a pair of hexameric Au6(S3Cl4) motifs. It is noteworthy that the"Au-Cl-Au" staple motifs are observed for the first time in thiolate protected gold nanoclusters. More importantly, the formation of the Cl-Au3 motifs is found to be mainly responsible for the configuration of the gold nanocluster. This work will offer a new perspective to understand how the ligands affect the crystal structure of gold nanocluster.2. We once again used dynamics method which is adopted to control the synthesis of nano clusters of gold by changing the types of weak reductant. In result, we got the organic selenium ligands to protect gold nano clusters Au24(SePh-tBu)20, its structural framework is very similar to Au24(SePh)20 which has reported for duty. It’s interesting that Au24(SePh-tBu)2o and Au24(SePh)20 have similar structural framework, but they have different ultraviolet absorption spectrum. We think these two clusters have different in the ultraviolet absorption spectrum maybe due to the-tBu (the different between SePh-tBu and SePh).