Liu Suyi, Norikane Yasuo, Tsuzuki Seiji, Ito Shotaro, Kikkawa Yoshihiro
Graduate School of Science and Technology, University of Tsukuba, Ibaraki 305-8571, Japan.
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1- 1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
Phys Chem Chem Phys. 2023 Apr 12;25(15):10917-10924. doi: 10.1039/d3cp00368j.
Well-ordered molecular arrangement on surfaces is fundamental for fabrication of functional molecular devices which are of particular interest in nanotechnology. In addition to nano-manufacturing, the production of useful materials from natural resources has recently attracted increasing attention. Herein, we focused on the two-dimensional (2D) self-assemblies of curcumin derivatives. The effects of the number, length, and substitution of the alkyl chains on the 2D structures of curcumin derivatives were studied by scanning tunnelling microscopy at the highly oriented pyrolytic graphite/1,2,4-trichlorobenzene interface. Curcumin derivatives containing both methoxy and alkoxy chain groups and those possessing four alkoxy chains exhibit linear structures with and without interdigitation of alkoxy chains, respectively. These 2D structure formations are independent of the alkyl chain length. However, the bisdemethoxycurcumin derivatives periodically form stair-like and linear structures depending on the alkyl chain length, which indicates the existence of the odd-even effect. These results suggest that the 2D structural modulation of curcumin derivatives caused by the odd-even effect can be tuned by the number of alkyl chain substituents. The appearance and disappearance of the odd-even effect in curcumin derivatives are discussed in terms of the balance between intermolecular and molecule-substrate interactions.
表面上有序的分子排列对于制造功能分子器件至关重要，而功能分子器件在纳米技术中备受关注。除了纳米制造之外，利用自然资源生产有用材料近来也越来越受到关注。在此，我们聚焦于姜黄素衍生物的二维自组装。通过扫描隧道显微镜在高度定向热解石墨/1,2,4-三氯苯界面研究了烷基链的数量、长度和取代基对姜黄素衍生物二维结构的影响。同时含有甲氧基和烷氧基链基团的姜黄素衍生物以及具有四条烷氧基链的姜黄素衍生物分别呈现出具有和不具有烷氧基链相互交错的线性结构。这些二维结构的形成与烷基链长度无关。然而，双去甲氧基姜黄素衍生物会根据烷基链长度周期性地形成阶梯状和线性结构，这表明存在奇偶效应。这些结果表明，奇偶效应引起的姜黄素衍生物二维结构调制可通过烷基链取代基的数量进行调节。从分子间相互作用与分子-底物相互作用之间的平衡角度讨论了姜黄素衍生物中奇偶效应的出现与消失。
