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Direct observation of molecular chirality and molecular reaction on solid surface

直接观察固体表面上的分子手性和分子反应

基本信息

批准号：
13640551
负责人：
TANIGUCHI Masahiro
金额：
$ 2.24万
依托单位：
Kanazawa Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640551/
关键词：
scanning tunneling microscopy solid surface gold surface molecular chirality optical activity molecular recognition thin film helicene 不斉識別

项目摘要

Pasteur's discovery of spontaneous resolution of the sodium ammonium tartaric acid introduced the basic idea of chirality into chemistry. The microscope of his age helped him to distinguish the outlook of two enantiomorphous crystals one by one. Since then, the development of the scanning probe microscope (SPM), such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM), made it possible to image not only the asymmetry of the crystal lattices but also individual molecules. In this work, the molecular recognition based on chirality was elucidated. Monolayers of hexathia[11]heterohelicene ([11]TH), which consists of 5 benzene rings and 6 thiophene rings were prepared on gold substreates under 1 UHV condition. [11]TH has a bulky structure of helically annulated aromatic rings which is suitable for imaging of molecular chirality. [11]TH was used in racemic form in this work. Low energy electron diffraction (LEED) and STM were used for the structural study of the monolayers. [11]TH monolayer on gold(111) substrate showed the same structure as on (111) analogue of polycrystalline surface. It showed six-fold symmetry lattice which suggested no chiral recognition between molecules. The image taken on the terrace top demonstrated the chirality imaging of individual molecule in the racemic glass phase. [11]TH evaporated on gold(110) showed loosely packed molecular chains. But the chains of [11]TH gave no distinctive sign of chiral interaction. On the other hand, the arrays formed on the step bunching region of polycrystal surface showed the isomorphic chiral chains. The results suggested that the substrate structure affected the spacing and configuration of the adsorbed molecules. And these two factors determined the contribution of the chirality of the adsorbates to the monolayer structure.

巴斯德发现酒石酸铵钠的自发分解，将手性的基本思想引入化学。他那个年龄的显微镜帮助他区分了两个对形晶体的外观。此后，扫描探针显微镜（SPM）的发展，如扫描隧道显微镜（STM）和原子力显微镜（AFM），使得不仅可以成像晶格的不对称性，而且可以成像单个分子。本文对基于手性的分子识别进行了阐述。在1特高压条件下，在金衬底上制备了由5个苯环和6个噻吩环组成的六硫醚[11]TH （[11]TH）单分子层。[11]TH具有螺旋环形芳香环的庞大结构，适合于分子手性成像。[11]TH在本研究中以消旋形式使用。利用低能电子衍射（LEED）和STM技术对单层膜的结构进行了研究。在金（111）衬底上的[11]TH单层显示出与（111）类似多晶表面相同的结构。它具有六重对称晶格，表明分子之间没有手性识别。在平台顶部拍摄的图像显示了外消旋玻璃相中单个分子的手性成像。在金（110）上蒸发的TH显示出松散的分子链。但b[11]TH链没有明显的手性相互作用迹象。另一方面，在多晶表面的阶梯聚束区形成的阵列显示出同形手性链。结果表明，底物结构影响了吸附分子的间距和构型。这两个因素决定了吸附剂的手性对单层结构的贡献。