Scanning tunneling microscopy observation of self-assembled monolayers of strapped porphyrins.
Scanning tunneling microscopy observation of self-assembled monolayers of strapped porphyrins.
复制标题
带状卟啉自组装单层的扫描隧道显微镜观察。
作者：
Taichi Ikeda;M. Asakawa;K. Miyake;M. Goto;T. Shimizu
本文揭示了具有长烷基链的游离碱和带锌的卟啉分别为C24OPP-HQ和锌(C24OPP-HQ)可以排列在表面。我们使用扫描隧道显微镜(STM)观察了这些被捆绑的卟啉在固-液界面上的烷基链辅助自组装单分子膜(SAM)。STM图像显示，在卟啉核心上可以检测到绑定的苯部分：也就是说，绑定的卟啉可以与非绑定的类似物区分开来。我们比较了混合自组装膜中无带卟啉(C24OPP)和有带卟啉C24OPP-HQ或锌(C24OPP-HQ)的数量。然后我们证实了锌(C24OPP-HQ)比C24OPP-HQ更有利于掺入混合自组装膜中。(1)核磁共振氢谱和X-射线结晶学分析表明，锌配位增加了锌(C24OPP-HQ)在混合自组装膜中的布居，这是由于锌配位增强了卟啉核的刚性和卟啉部分在马鞍状构象中的平坦结构。这项研究表明，具有长烷基链的带状卟啉可以通过对带状部分的化学修饰来在表面上排列功能模块。
In this paper, we reveal that the free-base and zinc strapped porphyrins possessing long alkyl chains, C 24OPP-HQ and Zn(C 24OPP-HQ), respectively, can be arranged on surfaces. We used scanning tunneling microscopy (STM) to observe alkyl-chain-assisted self-assembled monolayers (SAMs) of these strapped porphyrins at the solid-liquid interface. STM images revealed that the strapped benzene moiety was detectable on the porphyrin core: that is, the strapped porphyrins could be differentiated from nonstrapped analogues. We compared the population of the nonstrapped porphyrin (C 24OPP) and either of the strapped porphyrins C 24OPP-HQ or Zn(C 24OPP-HQ) in the mixed SAMs. We then confirmed that Zn(C 24OPP-HQ) is more favorably incorporated in the mixed SAMs than C 24OPP-HQ. From (1)H NMR spectroscopic and X-ray crystallographic analyses, we concluded that the factors increasing the population of Zn(C 24OPP-HQ) in the mixed SAMs are the enhanced rigidity of the porphyrin core by the zinc coordination and the flat structure of the porphyrin moiety in the saddle conformation. This study demonstrates that strapped porphyrins possessing long alkyl chains are available to arrange the functional modules on the surface via chemical modification on the strapped moiety.