超原子分子理论若干概念及其在配体包覆金属团簇中的应用

发布时间：2018-01-20 02:24

本文关键词： 纳米团簇超原子超原子分子理论等同超原子杂化超原子网络密度泛函理论　出处：《中国科学技术大学》2017年博士论文　论文类型：学位论文

【摘要】：纳米材料是现代科技和新型学科发展的基础,是纳米科技最为重要的研究对象。按照空间维度划分,纳米材料可分为零维、一维、二维以及三维纳米材料。零维纳米材料中,尺寸相对较小的称为纳米团簇,而尺寸相对较大的一般称作纳米颗粒。纳米团簇简称团簇,已经发展成为一门重要的学科"团簇科学"。在团簇科学领域,金属团簇是非常重要的分支。从质谱实验发现钠原子团簇的幻数序列开始,到凝胶模型以及超原子概念的引入,再到三维元素周期表的设想,团簇领域中各种理论模型和精巧的实验陆续被报道。这些研究中,一个重要且充满挑战的课题就是利用超原子进行结构组装,从而形成超分子或超原子组装材料。但是,目前超原子组装仍存在理论盲区。研究者对如何进行超原子组装并没有清晰的理论认识。缺乏理论指导的超原子拼接很难保证其结果的合理性,以及结构的稳定性。因此,梳理超原子间相互作用形式,分析和建立超原子间成键规则及组装模式,进而形成系统的理论框架对超原子组装、超原子结构设计及新型团簇结构的实验合成均意义重大。本论文旨在发掘超原子间的成键类型和组装模式,构建和完善超原子分子理论,为新型团簇的结构设计、组装以及合成提供理论依据。论文总共分五章:第一章介绍团簇研究相关背景。首先从团簇研究的主要理论方法,密度泛函理论开始,介绍了密度泛函理论从诞生到成熟的一些重要的理论模型和定理。然后对一些解释团簇结构及稳定性的理论进行了简单介绍。重点介绍了针对金属团簇的凝胶模型,然后是针对硼烷及过渡金属配合物的多面体骨架电子对理论,最后对衡量团簇稳定性的芳香性规则做了简单介绍。这些理论各有特点及使用范围,从不同的角度对不同类型团簇的结构及稳定性给出了理解。第二章介绍超原子分子理论目前所涵盖的主要内容。从超价键模型出发,将目前超原子成键类型总结概括为三类,即超级共价键、超级杂化键和超级非键。这些认识加上新提出的等同超原子概念,杂化超原子网络模型等内容,分别从超原子成键类型、组装基元以及组装模式等方面给出了理解,构成了较为系统的超原子分子理论。其中等同超原子和杂化超原子网络在第三章和第四章会重点阐述。第三章基于对团簇组装基元的思考,提出了等同超原子概念并介绍其应用实例。这一章首先给出了等同超原子概念的由来,及判定方法。然后结合实验结果指出由等同超原子可以形成超分子。最后,结合实验结果展示了若干等同超原子如何形成等同超分子。等同超原子概念的提出不仅可以解释已有理论无法解释的实验结果,还为超原子组装提供了更多的组装基元。第四章重点阐述一种超原子组装模式,即杂化超原子网络。该组装模式的特点是超原子先通过超级非键形成共轭超原子网络,然后若干共轭超原子网络通过配体链接组成更大的团簇体系。应用该模型可以解释一系列配体金团簇的结构稳定性。同时,基于对该系列团簇的结构分析,提出了其结构演化规则,即Au13拓扑规则。本章的结论不仅可以解释团簇的结构稳定性,而且对团簇的结构预测和团簇的实验合成均有重要意义。第五章包含四个理论与实验结合的工作。分别研究了两个Ag原子掺杂Au25纳米团簇的结构和光学性质;研究了 Hg原子掺杂Au25团簇时可能的掺杂位点;研究了Pdn(SR)2n系列团簇的几何结构,成键以及光学性质;研究了 Au原子掺杂Pdn(SR)2n系列团簇的结构和性质。这些工作中的理论数据及分析均很好的解释、佐证或补充了实验结果。
[Abstract]:Nano material is the foundation of modern science and technology and the development of new disciplines, is one of the most important research object for nano technology. According to the spatial dimension, the nano materials can be divided into zero dimensional, one-dimensional, two-dimensional and three-dimensional nanomaterials. Zero dimensional nano materials, a relatively small size called nano clusters, and the relatively large size the general called nano particles. The nanoclusters referred to as clusters, has become an important subject of "cluster science". In the field of cluster science, metal clusters are very important branch. It was found that sodium cluster sequence starting from the magic number of mass spectrometry experiments, gel model and the introduction of ultra atomic concept and then to visualize the three-dimensional periodic table, various theoretical models in the field of clusters and ingenious experiments have been reported. In these studies, an important and challenging task is to use the super atomic structure and assembly. The formation of supramolecular assembly materials or super atom. But at present, there are still blind super atomic assembly theory. The researchers assembled on how super atom does not know clearly the lack of super atomic theory. Guided by the theory of splicing is very difficult to guarantee the rationality of the results, and the stability of the structure. Therefore, combing the interaction between atoms form super and the analysis and establishment of rules and key assembly modes into super atoms, thus forming the theoretical framework of the system of super atomic assembly, experimental synthesis of super cluster structure design and model group of atomic structure are of great significance. This paper aims to explore the super key type and assembly mode between atoms, and perfect the construction of super atomic and molecular theory the design for the new structure, clusters, assembly and synthesis and provide a theoretical basis. This paper is divided into five chapters: the first chapter introduces the cluster related research background. First from the main cluster on the side Start method, density functional theory, introduce the density functional theory from birth to maturity of some important theoretical model and theorem. Then some explanation of cluster structure and stability theory are introduced. Emphatically introduces the gel model for metal clusters, and then for the polyhedral skeletal electron borane and transition metal complexes in theory, finally aromaticity rules to measure the stability of clusters is introduced. These theories have their own characteristics and scope of application, from different angles on different types of cluster structure and stability were given solutions. The second chapter introduces the main content of super atomic and molecular theory currently covered. Starting from the high price the key model will present superatomic types summarized into three categories, namely super covalent, super hybrid bond and non bond. These super plus new super equal atomic concept, Super hybrid atomic network model, respectively from the superatomic element type, assembly and assembly mode etc. given the understanding, constitute a super atomic and molecular theory systematically. The super hybrid super atom atom and the equivalent network in the third and fourth chapter. The third chapter will focus on consideration of clusters the assembly bases, put forward the same super atomic concepts and introduces the application examples. This chapter first gives the origin of the concept of equivalent super atom, and the determination method. And then combined with the experimental results pointed out that the supramolecular formed by atoms can be super equal. Finally, combining the experimental results show some equivalent super atom to form supramolecular equivalent is proposed. With super atomic concepts can not only explain the experimental results could not be explained by existing theories, but also for the super atom assembly provides more assembly bases. The fourth chapter focuses on a super Atomic assembly model, namely the hybrid super atom network. Characteristics of the assembly model is the first super super atom through non conjugated bond forming super atom network, then some conjugated super atom network through ligand links consisting of clusters larger. The model can be used to explain the structural stability of a series of ligands of gold clusters. At the same time, analysis the structure of the series of clusters based on the proposed rules, the evolution of its structure, namely Au13 topological structure stability rules. The conclusion of this chapter can not only explain the clusters, and both structure prediction and experimental synthesis of group cluster cluster significance. The fifth chapter contains the combination of the four theoretical and experimental work. The structure and optical properties of two Ag atoms doped Au25 nanoclusters were studied; study of Hg doped Au25 clusters doped sites cluster possible; Pdn (SR) on the geometry structure of 2n clusters, a key to And optical properties. The structure and properties of Au atom doped Pdn (SR) 2n clusters are studied. The theoretical data and analysis in these works are very good explanations, which confirm or complement the experimental results.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O641

【相似文献】