【作者】 胡懿； 许莉； 缪锴； 查宝； 苗新蕊； 邓文礼；

【Author】 Yi Hu;Li Xu;Kai Miao;Bao Zha;Xinrui Miao;Wenli Deng;South China University of Technology;

【机构】 华南理工大学；

【摘要】 分子自组装是自然界中常见的一种现象,尤其是在物理、化学、生物体系中。自组装作为由下而上的一种方法,已经成为在纳米新材料领域通过原位调控构建特定结构,并使之具有特定性能的有效手段。^[1]在不同维度、不同环境的自组装中,固/液界面的二维自组装发挥着重要的作用。^[2]碳链取代的分子可以通过范德华力、氢键、π-π堆积、金属-有机配位、卤键、静电作用力等在基底上自组装成有序的纳米结构。因此对于碳链取代的体系而言,改变碳链长度成为获得不同结构的一种简单手段。^[3]我们系统地研究了三取代蒽醌衍生物（1,2,4-A-3OC_n,n=15-18）在辛酸/石墨界面的自组装构象的多样性。就我们所知,三取代蒽醌衍生物在石墨基底上的自组装还从未被报道过。我们观察到了五种自组装结构:线性I,线性Ⅱ,线性Ⅲ,蝶状,以及二聚体-线性结构。在其中四种结构中,分子都是以成对的方式排列,这归因于静电相互作用以及偶极-偶极相互作用。溶剂分子通过COOH···O=C和COOH···COOH的氢键方式共吸附在溶质分子的结构空位中。另外,分子-基底、分子-分子间的范德华力可以通过改变碳链长度去调控。1,2,4-A-3OC₁₆分子在辛酸/石墨界面的自组装表现出了浓度效应。随着浓度逐渐降低,从饱和浓度,中等浓度,到低浓度,我们观察到了结构转变。总体而言,1,2,4-A-3OC_n（n=15-18）分子的自组装是可以通过结构与浓度去调控的,而本研究结果将为设计烷烃链取代的超分子以及构建整齐排列的单层膜提供简单且有效的策略。更多还原

【Abstract】 Molecular self-assembly is a ubiquitous phenomenon in nature, especially in many physical, chemical and biological systems. It has been proved to be an efficient approach as bottom-up to fabricate a given structure, property or function in new materials at nanoscale by local manipulation.^[1]Among the different dimensionalities and environments for assembly, two dimensional（2D） monolayer at the liquid/solid interface plays a special role. ^[2]The alkyl chain substituted molecules can self-assembly into ordered nanostructures via van der Waals, hydrogen bonding, π-π stacking, metal coordination, halogen bonds and electrostatic interactions.^[3]Hence for the alkyl chain substituted system, it is easy to change the networks by increasing or decreasing the chain length. We systematically studied the formation of nanostructures of tri-substituted anthraquinone derivatives（1,2,4-A-3OC_n, n = 15 to 18） on the highly oriented pyrolytic graphite（HOPG） with 1-octanoic acid as the solvent. To the best of our knowledge, it is the first time to demonstrate the anthraquinone derivatives with three side chains in the field of 2D molecular self-assembly. Five different networks, named as Linear I, Linear II, Linear III, Butterfly-like and Dimer-Linear were observed, and molecules in four of them tend to be arranged in pairs, ascribing to the electrostatic forces and dipole-dipole interactions. Besides, solvent molecules co-adsorbed in the voids among the 1,2,4-A-3OC_n molecules via COOH···O=C and COOH···COOH hydrogen bonds. Except for these interplays, we also focus on another noncovalent force of van der Waals interaction. The strength between molecule-molecule and molecule-substrate can be tuned by gradual elongation of the alkyl chains. Moreover, the patterns for 1,2,4-A-3OC₁₆ at the 1-octanoic acid/HOPG interface were concentration-dependent. As the concentration decreased from saturated to middle, then to low, gradual structural transition was recorded. In general, the 2D arrangements for 1,2,4-A-3OC_n（n = 15 to 18） molecules are under the regulation of both structure control and concentration control. These results pave simple and efficient strategies for designing alkylated supramolecules and fabricating ordered monolayers.更多还原