OPE和PBM分子在石墨表面自組裝結構的STM研究
發(fā)布時間：2018-12-15 07:20
【摘要】：本論文利用掃描隧道顯微技術(STM)為主要研究手段,結合密度泛函理論計算(DFT)研究了兩種有機化合物在石墨表面的吸附行為,提出了通過客體分子的濃度調控組裝結構的研究新思路。選取兩組功能化合物體系,研究了其表面的吸附行為,總結分子在表面組裝特點和規(guī)律。主要研究結果如下:一、利用STM技術與DFT計算相結合,研究了一系列不同長度的骨架和側鏈的低聚芳撐乙炔分子(OPE)分子在石墨表面的自組裝結構。研究發(fā)現(xiàn),這些低聚物根據(jù)它們的化學結構的不同可以形成不同的自組裝結構,其中兩個分子間側鏈形成的分子間相互作用的不同是主要影響因素。這些組裝的結構通過兩分子之間的側鏈交叉以及分子和HOPG底物之間形成的范德華力結合在一起。這些研究將在功能性共軛分子的設計和應用中提供重要的指導。二、利用STM研究了兩種共軛芳香大環(huán)分子(PBM)在石墨表面的自組裝。主要探究了主體分子的大小,形狀和客體分子的濃度對PBMs/COR主-客體系統(tǒng)自組裝的影響。STM圖像顯示PBM1(主體部分為三角形)分子呈現(xiàn)規(guī)則的線性網(wǎng)絡結構,而PBM2(主體部分為四邊形)分子形成了有序的納米孔網(wǎng)絡結構。當引入客體分子COR分子時,PBM1的自組裝結構保持不變,而PBM2分子則可以與客體分子形成主客體組裝結構。此外,隨著客體分子COR濃度的增加,PBM2/COR組裝結構發(fā)生變化。借助密度泛函理論計算,發(fā)現(xiàn)在引入COR客體分子后,尺寸匹配和濃度依賴效應在PBM2主機網(wǎng)絡的結構轉換中起著重要的作用。該工作將有助于我們深入了解表面上自組裝和控制分子圖形形成的動態(tài)過程。
[Abstract]:In this paper, the adsorption behavior of two organic compounds on graphite surface was studied by means of scanning tunneling microscopy (STM) and density functional theory (DFT). A new way to study the assembly structure by the concentration regulation of guest molecules is proposed. The adsorption behavior of two groups of functional compounds on the surface was studied, and the characteristics and rules of molecular assembly on the surface were summarized. The main results are as follows: firstly, the self-assembly structure of a series of (OPE) molecules with different lengths of skeleton and side chain on graphite surface has been studied by using STM technique and DFT calculation. It is found that these oligomers can form different self-assembled structures according to their different chemical structures, in which the intermolecular interactions formed by the side chains between two molecules are the main influencing factors. These assembled structures are bound by the side chain crossing between the two molecules and the van der Waals force formed between the molecule and the HOPG substrate. These studies will provide important guidance in the design and application of functional conjugated molecules. Secondly, STM was used to study the self-assembly of two conjugated aromatic macrocyclic molecules (PBM) on graphite surface. The effects of the size, shape and concentration of host molecule on the self-assembly of host guest system of PBMs/COR are studied. STM images show the linear network structure of PBM1 (the host part is triangular). However, PBM2 (quadrilateral) molecules form an ordered network structure of nano-pores. When the guest molecule COR molecule is introduced, the self-assembly structure of PBM1 remains unchanged, while the PBM2 molecule can form the host-guest assembly structure with the guest molecule. In addition, the PBM2/COR assembly structure changes with the increase of the concentration of guest molecule COR. Based on density functional theory (DFT), it is found that the size matching and concentration dependent effects play an important role in the structural transformation of PBM2 host networks after the introduction of COR guest molecules. This work will help us to understand the dynamic process of surface self-assembly and controlling the formation of molecular patterns.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O647.31
本文編號：2380236
[Abstract]:In this paper, the adsorption behavior of two organic compounds on graphite surface was studied by means of scanning tunneling microscopy (STM) and density functional theory (DFT). A new way to study the assembly structure by the concentration regulation of guest molecules is proposed. The adsorption behavior of two groups of functional compounds on the surface was studied, and the characteristics and rules of molecular assembly on the surface were summarized. The main results are as follows: firstly, the self-assembly structure of a series of (OPE) molecules with different lengths of skeleton and side chain on graphite surface has been studied by using STM technique and DFT calculation. It is found that these oligomers can form different self-assembled structures according to their different chemical structures, in which the intermolecular interactions formed by the side chains between two molecules are the main influencing factors. These assembled structures are bound by the side chain crossing between the two molecules and the van der Waals force formed between the molecule and the HOPG substrate. These studies will provide important guidance in the design and application of functional conjugated molecules. Secondly, STM was used to study the self-assembly of two conjugated aromatic macrocyclic molecules (PBM) on graphite surface. The effects of the size, shape and concentration of host molecule on the self-assembly of host guest system of PBMs/COR are studied. STM images show the linear network structure of PBM1 (the host part is triangular). However, PBM2 (quadrilateral) molecules form an ordered network structure of nano-pores. When the guest molecule COR molecule is introduced, the self-assembly structure of PBM1 remains unchanged, while the PBM2 molecule can form the host-guest assembly structure with the guest molecule. In addition, the PBM2/COR assembly structure changes with the increase of the concentration of guest molecule COR. Based on density functional theory (DFT), it is found that the size matching and concentration dependent effects play an important role in the structural transformation of PBM2 host networks after the introduction of COR guest molecules. This work will help us to understand the dynamic process of surface self-assembly and controlling the formation of molecular patterns.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O647.31
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，本文編號：2380236
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