异代酯基枝状分子表面组装及结构转化机理的STM研究

高等学校化学学报 ›› 2009, Vol. 30 ›› Issue (12): 2424.

异代酯基枝状分子表面组装及结构转化机理的STM研究

张旭^1,2, 冯宇^1,2, 范青华¹, 万立骏¹

1. 中国科学院化学研究所, 北京 100190;
2. 中国科学院研究生院, 北京 100049

收稿日期:2009-06-02 出版日期:2009-12-10 发布日期:2009-12-10
通讯作者: 万立骏, 男, 博士, 研究员, 博士生导师, 主要从事物理化学及纳米材料研究. E-mail: wanlijun@iccas.ac.cn; 范青华, 男, 研究员, 博士生导师, 主要从事分子识别及催化不对称合成研究. E-mail: fanqh@iccas.ac.cn
基金资助:
国家自然科学基金(批准号: 20733004, 20821003)资助.

Self-assembled Structures and Structural Transition of Dimethyl Isophthalate-Functionalized Janus Dendrimers on HOPG Investigated with STM

ZHANG Xu^1,2, FENG Yu^1,2, FAN Qing-Hua^1*, WAN Li-Jun^1*

1. Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China

Received:2009-06-02 Online:2009-12-10 Published:2009-12-10
Contact: WAN Li-Jun. E-mail: wanlijun@iccas.ac.cn; FAN Qing-Hua. E-mail: fanqh@iccas.ac.cn
Supported by:
国家自然科学基金(批准号: 20733004, 20821003)资助.

摘要/Abstract

摘要：

利用扫描隧道显微技术(STM)研究了3种异代酯基Janus枝状分子(G₁G₂COOCH₃, G₀G₃COOCH₃, G₁G₃COOCH₃)在高定向裂解石墨(HOPG)表面的组装结构. 室温下, G₁G₂COOCH₃, G₀G₃COOCH₃和G₁G₃COOCH₃分别在表面形成有序、局部有序及无序结构. 将样品加热至60~80 ℃后, 表面无序结构可以转化为有序的二聚体密堆积结构. 实验结果表明, 随着枝状分子代数的增加, 分子之间及分子与基底之间作用力增强, 室温下分子组装行为更依赖于分子吸附动力学过程, 组装结构趋于无序化, 而加热可以增强枝状分子在表面的活动性, 调整分子的位置关系, 使表面无序结构转化为热力学稳定的有序二聚体密堆积组装结构.

关键词: Janus枝状分子; 自组装; 结构转化; 扫描隧道显微术

Abstract:

Self-assembled structures of three dimethyl isophthalate-functionalized Janus dendrimers G₁G₂COOCH₃, G₀G₃COOCH₃, and G₁G₃COOCH₃ were investigated with scanning tunneling microscopy(STM) on HOPG. It was found that G₁G₂COOCH₃, G₀G₃COOCH₃, G₁G₃COOCH₃ assembled into ordered, partial ordered, and disordered structures, respectively. After heated to 60—80 ℃, regular dendrimer dimers could be found on HOPG, resulting in close-packed ordered structures instead of the previous disordered structures. The results show that with the increase of the molecule generation, molecules are bound down onto surface due to the enhanced intermolecular and molecule-substrate interactions. The self-assembly is dependent on the dynamic process, leading to disordered structures. However, when heated, the mobility of dendrimer molecules on surface could be improved. Structural transformation from disordered structures to thermodynamically stable dimeric structures could be observed by STM on G₀G₃COOCH₃ and G₁G₃COOCH₃ adlayers.

Key words: Janus dendrimer; Self-assembly; Structural transition; Scanning tunneling microscopy(STM)

TrendMD:

张旭, 冯宇, 范青华, 万立骏. 异代酯基枝状分子表面组装及结构转化机理的STM研究. 高等学校化学学报, 2009, 30(12): 2424.

ZHANG Xu, FENG Yu, FAN Qing-Hua*, WAN Li-Jun*. Self-assembled Structures and Structural Transition of Dimethyl Isophthalate-Functionalized Janus Dendrimers on HOPG Investigated with STM. Chem. J. Chinese Universities, 2009, 30(12): 2424.

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