有机硒配体保护的金纳米团簇的直接合成，结构及其性质研究

发布时间：2018-01-19 12:19

本文关键词： 苯硒酚金纳米团簇结构性质配体交换　出处：《安徽大学》2017年博士论文　论文类型：学位论文

【摘要】：原子精确的金属纳米团簇作为一种新兴的纳米材料在纳米科学领域引起了广泛的研究。与传统的金属纳米颗粒(NPs)相比,原子精确的金属纳米团簇的优势在于:1)超小的尺寸(2nm)使其具有很强的量子尺寸效应,从而使其具有独特的物理化学性质,比如离散型能级,强荧光,良好的催化性能,很强的非线性吸收等。2)可以在原子水平上控制它们的尺寸,得到原子数目单一的金属纳米团簇,这对研究其尺寸与物理化学性质之间的关系具有非常重要的意义,对合成纳米材料具有指导性作用。3)可以通过单晶衍射仪得到它们精确的分子结构,从而了解有机配体与金属之间的结合方式,以及金属原子的排列方式,从而进一步研究结构与性质之间的关系。目前,在这些金属纳米团簇中,硫醇配体保护的金纳米团簇无论是在结构,还是在性质等方面,都得到了广泛的关注。近年来,有机硒配体保护的金纳米团簇的一些性质也得到了研究。研究发现,有机硒配体保护的金纳米团簇具有良好的稳定性和独特的光学性质。但是,由于合成方法的繁琐及产率低,仍然没有相关晶体结构的报道,这在一定程度上阻碍了有机硒配体保护的金纳米团簇的发展。而本文通过对合成条件的摸索与研究,探索出了一种快速,高产率的合成方法,并且成功得到了有机硒配体保护的金纳米团簇的晶体结构。在晶体机构的基础上,分别对它们的光学性质,电化学性质,催化性质等方面进行了研究。此外我们还结合了密度泛函理论(DFT),从电子结构方面对其物理化学性质进行了更进一步的解析。这不仅为有机硒配体保护的金纳米团簇的进一步研究提供了坚实的实验和理论基础,同时也为整个金属纳米团簇的研究方向提供了更多的选择性。本文主要研究内容包括:1.在本文中,我们巧妙地利用"共还原法",即同时滴加配体和还原剂,成功地,高产率地合成了苯硒酚配体保护的Au25纳米团簇。在此基础上,它的晶体结构得到了表征,与硫醇配体保护的Au25纳米团簇类似,包含一个二十面体的Au13核和6个"V-型"的Au2(SeR)3书钉状结构(staplemotifs)。尽管如此,它们之间还是有一些不同的。此外,我们对其电化学性质,催化性质,光学性质进行了研究。结果表明,配体的改变对Au25纳米团簇的电子结构和物理化学性质具有非常大的影响。2.通过共还原的方法,我们成功制备了苯硒酚配体保护的Au24纳米团簇,并且得到了它的晶体结构。结果显示,该团簇包含一个由两个四面体交叉排列组成的Au8核,外围被一对Au3Se4和一对Au5Se6的staple motifs保护,形成了一个类似"蝴蝶"的扁长形结构。其中Au8核和Au5Se6 staple motif在金纳米团簇中是第一次被发现。这为进一步了解硒配体保护的金纳米团簇提供了结构依据。3.此外,与S原子相比,Se原子除了具有半径长之外,它还有配位能力强的特点。因此,在双配体保护的金纳米团簇体系中,我们用苯硒酚代替硫醇配体,成功合成了[Au60Se2(PPh3)10(SePh)15]+纳米团簇,并且得到了它的晶体结构。结果显示,该团簇由5个二十面体的Au13基本单元通过"Au-Se-Au"组合在一起,形成一个环形的结构。值得一提的是,在该结构中,我们首次发现了两个独特的Se原子,分别以"Se-Au5"的方式存在,这在金纳米团簇中是从来没有的。另外,我们分别对其结构,电化学性质,光学性质等方面进行了研究。结果表明,在该团簇组装材料中,Au13基本单元的电子结构性质基本上没有发生改变。4.通过对实验条件的优化,我们成功合成了带有不同电荷的棒状[Au25(PPh3)10(SePh)5Cl2]q(q = +1,+2)纳米团簇,并得到了它们的晶体结构—两个Au13单元通过共顶点的方式存在。在该体系中,我们详细的研究了单电子对棒状Au25纳米团簇的结构及化学性质的影响。结果表明,在棒状体系("非超原子")中,单电子对团簇的结构及物理化学性质同样有着非常显著的影响,尤其是光学性质和磁性方面。这在一定程度上让我们对金纳米团簇有了新的认识。5.根据"驱动力"的概念,在硼氢化钠的作用下,我们成功将Au25(SePh)18纳米团簇通过配体交换的方法转化为苯乙硫醇保护的Au25纳米团簇。值得注意的是,产物中的Au-S键是比Au-Se键弱的。此外,通过条件独立实验,我们进一步研究其交换的机理。研究发现,在硼氢化钠的作用下,Au25(SePh)18纳米团簇可以直接失去两个Au-SePh单元而转化为Au23(SePh)16纳米团簇。有趣的是,在过量的硫醇条件下,Au23(SePh)16纳米团簇会转变成混合配体保护的Au25纳米团簇,即同时发生了配体交换和尺寸改变。并且这种配体交换过程可以通过硼氢化钠来控制。这种反应机制也是第一次报道,这为我们对团簇转化以及配体交换的进一步理解和认识提供新的观点及依据。
[Abstract]:Metal nanoclusters accurate atomic as a kind of new nano materials has attracted extensive research in the field of nanotechnology. With traditional metal nanoparticles (NPs) compared with that of metal nanoclusters accurate atomic advantages: 1) ultra small size (2nm) which has strong quantum size effect thus, the unique physical and chemical properties, such as discrete level, strong fluorescence, good catalytic properties, nonlinear absorption,.2 strong) can control their size at the atomic level, the number of single atoms of metal nanoclusters, which has very important significance to study the relationship between the size of with the physical and chemical properties, which is the guide of.3 on the synthesis of nano materials) can get their precise molecular structure by X-ray diffraction instrument, so as to understand the binding mode between organic ligands and metal, and metal The arrangement, in order to further study the relationship between structure and properties. At present, the metal nanoclusters, gold nanoclusters thiol ligand protected either in structure or in nature, etc., has received extensive attention. In recent years, some properties of gold nanoclusters ligand protected organic selenium the has also been studied. The study found that ligand protected gold clusters of organic selenium has good stability and unique optical properties. However, due to the cumbersome and low yield of synthesis, crystal structure is still not reported, which hindered the development of gold nanoclusters ligand protected organic selenium in extent. And to explore and Research on the synthesis condition through the search for a rapid, synthetic method of high yield, and successfully obtained crystal structure of gold nanoclusters ligand protected organic selenium in the crystal. Based on the structure, electrochemical properties and optical properties, respectively, on their catalytic properties, and other aspects of the study. In addition, we also combined with density functional theory (DFT), makes a further analysis on the physical and chemical properties of the electronic structure. It not only for further research on organic ligand protected gold clusters se provides experimental and solid theoretical foundation, but also the research direction for the entire metal nanoclusters provides more selective. The main contents of this paper include: 1. in this paper, we skillfully use "coreduction method", namely, dropping the ligand and reducing agent, successfully, high yield the synthesis of Au25 nano clusters selenophenol ligand protection. On this basis, its crystal structure has been characterized, Au25 nanoclusters and thiol ligand protected similar, contains a twenty Au13 nuclear body surface and 6 "V- Type "Au2 (SeR) nail like structure of 3 books (staplemotifs). However, there are still some differences between them. In addition, we on the electrochemical properties, catalytic properties and optical properties were studied. The results showed that the change of ligand Au25 nanoclusters electronic structure and physicochemical properties of.2. very large by the co reduction method, we successfully prepared Au24 nanoclusters selenophenol ligand protected by, and obtained its crystal structure. The results show that the cluster contains a tetrahedron composed of two staggered Au8 core periphery by a pair of Au3Se4 and a pair of Au5Se6 staple motifs, formed a" Butterfly "prolate structure. The Au8 core and Au5Se6 staple motif in the gold nanoclusters were first found. This is to further understand the gold nanoclusters selenium ligand protected structure is provided according to this.3. , compared with the S atom, Se atom has long radius, it has characteristics of strong coordination ability. Therefore, the gold nanoclusters system of dual ligand protection, we replace the ligand with selenophenol, synthesized [Au60Se2 (PPh3) 10 (SePh) 15]+ clusters, and the crystal structure of it. The results show that the clusters by Au13 basic unit 5 twenty sides by "Au-Se-Au" together, forming a ring structure. It is worth mentioning that, in this structure, we first discovered two unique Se atom, not to exist "Se-Au5", which is never in the gold clusters. In addition, we were on the structure, electrochemical properties, optical properties and other aspects of the study. The results showed that in the cluster assembled materials in Au13, the basic unit of the electronic properties of the base is not changed by.4. Optimization of experimental conditions, we successfully synthesized [Au25 nanorods with different charges (PPh3) 10 (SePh) 5Cl2]q (q = +1, +2) clusters, and the crystal structure of - their two Au13 unit through the common vertex mode. In this system, we studied in details single electron structure and chemical properties of rod like Au25 nano clusters. The results showed that in the rod system ("non super atom"), structure and physical and chemical properties of clusters of single electron also has a very significant impact, especially the optical properties and magnetic aspects. It gives us a new understanding of.5. according to the concept of "driving force" of gold nanoclusters in a certain extent, the effect of sodium borohydride, we successfully Au25 (SePh) 18 nanoclusters by ligand exchange into Au25 nanoclusters phenylethyl mercaptan protection. It is worth noting that, in the product Au-S The key is weaker than the Au-Se bond. In addition, through independent experiments, we further study the exchange mechanism. The study found that the effect of sodium borohydride, Au25 (SePh) 18 nanoclusters can lose two Au-SePh units and converted to Au23 (SePh) 16 nanoclusters interesting. Is that in the condition of excess mercaptan (SePh), Au23 16 nano clusters will be transformed into Au25 clusters of mixed ligand protection, namely simultaneous ligand exchange and size change. And the ligand exchange process can be controlled by sodium borohydride. The reaction mechanism is also reported for the first time, this is further we understand the exchange of ligands and clusters transformation and provide a point of view and on the basis of a new understanding.

【学位授予单位】：安徽大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O641.4;TB383.1

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