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Study of Self-Assembling Mechanims of Thiol-Self-Assembled Monolayers

硫醇自组装单层膜的自组装机制研究

基本信息

批准号：
11640576
负责人：
KONDOH Hiroshi
金额：
$ 2.37万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The purpose of this research proposal is to understand microscopic mechanism of molecular self-assembly via. investigating formation process of self-assembled monolayers of thiol and related molecules by the use of STM and XAFS.In particular, we have been focusing on effects of molecule-substrate interactions on the self-assembly. The molecular orientation and the interface structure during self-assembling process have been investigated for different substrates (Au, Ag, Cu, O/Cu, Si). From systematic comparison for these substrates, we found three important factors to form well-ordered structures ; (1) sufficient molecular density, (2) surface diffusion and (3) consistency between intralayer and interface structures. It needs for achieving a well-ordered structure to satisfy all the three factors. We also found that the adsorption process is the rate-limiting step if the factor (1) is relatively important compared to the other factors while the diffusion process is the rate-limiting on … More e if the factor (2) is crucial. Another focusing point is effects of change in intermolecular interactions when introducing functional groups to the end of the alkanethiol molecules. Particularly, we have investigated self-assembly of thiophene- and porphyrin-introduced alkanethiols on gold substrates. In case of thiophene-introduced one, since the structure consistency as mentioned as factor (3) changes depending on molecular density, the self-assembly was found to take place only for a certain coverage range. In case of porphyrin-introduced molecules they exhibit no self-assembly unless the thiol group is spatially separated from the porphyrin moiety via.inserting long alkyl chains, because the large porphyrin moiety prevents the thiol group from having access to the substrate due to steric hindrance, which results in lower molecular density. Furthermore, we have investigated self-assembly of chalcogenophenes, of which structures are totally different from thiol, and found that selenophene (C_4H_4Se) forms a highly-ordered structure. Less

本研究计画的目的是透过分子自组装来了解分子自组装的微观机制。利用STM和XAFS研究了硫醇及其相关分子自组装膜的形成过程，特别是分子-基底相互作用对自组装膜形成的影响。研究了不同衬底（Au，Ag，Cu，O/Cu，Si）自组装过程中的分子取向和界面结构。通过对这些基底的系统比较，我们发现形成良好有序结构的三个重要因素：（1）足够的分子密度，（2）表面扩散和（3）层内和界面结构之间的一致性。它需要实现一个良好的有序结构，以满足所有这三个因素。我们还发现，如果因素（1）相对于其他因素重要，则吸附过程是限速步骤，而扩散过程是限速步骤。 ...更多信息如果因子（2）是关键的，则为e。另一个焦点是当在烷硫醇分子的末端引入官能团时分子间相互作用的变化的影响。特别地，我们研究了噻吩和卟啉引入的烷硫醇在金基底上的自组装。在噻吩引入的情况下，由于作为因子（3）提及的结构一致性取决于分子密度而变化，发现自组装仅在一定覆盖范围内发生。在卟啉引入的分子的情况下，它们不表现出自组装，除非硫醇基团通过插入长烷基链与卟啉部分在空间上分离，因为大的卟啉部分由于空间位阻而阻止硫醇基团接近基底，这导致较低的分子密度。此外，我们还研究了结构与硫醇完全不同的硫族酚的自组装，发现硒代酚（C_4H_4Se）形成了高度有序的结构。少