【作者】 牟忠诚；

【导师】 张希；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2005， 博士

【摘要】 有机分子在液/固界面上自组装可形成不同的聚集态结构,这些二维结构的差异主要取决于分子的自身结构、分子-分子、分子-基底间相互作用。对于二维组装体结构的调节与控制,则是在研究界面自组装结构基础上提出的又一个挑战。本论文利用刚性分子骨架上引入不同官能团调节单、双组分体系的二维有序结构。通过在不同长度烷基链取代的席夫碱分子骨架上引入甲氧基,比较研究甲氧基的空间位阻作用及烷基链长度的变化对其二维结构的影响,探索通过分子的剪裁调控其二维结构。同时,进行二维和三维结构的比较,找出两种结构上的差异及影响因素,为深入理解和解析二维结构寻求理论依据。喹吖啶酮及其衍生物的电致发光性能与生色团(分子核)在三维空间中的取向及排列方式密切相关。在分子核的不同部位引入小的取代基来调节其取向,以至于改进材料性能。本论文中,一方面研究甲基取代前后喹吖啶酮衍生物分子吸附在石墨表面形成的二维结构变化,讨论取代基对分子核取向的影响;另一方面,我们尝试利用喹吖啶酮衍生物分子作为主体分子,有机酸作为客体分子,进行共吸附,从而调控双组分体系二维结构。苯乙炔衍生物的齐聚物和聚合物,因其自身分子结构特点及电子性质,成为分子电子器件领域候选材料。本文设计合成了系列齐聚苯乙炔衍生物,使其刚性骨架两端取代不同官能团,及骨架中部引入联炔基,通过分子剪裁来调节这类分子的二维有序结构,为其将来的应用提供有价值的模型和二维结构信息。更多还原

【Abstract】 Organic molecules physiadsorb at liquid/solid interface, forming different assemblies, which are dependent on molecular structures, molecule-molecule interaction, molecule-substrate interaction. Compared with the studies of organic molecular assemblies at liquid/solid, the investigation of the modulation and controlling of the 2D structure is more important, and bigger challenge。In this dissertation, small substituents and different length of alkyl chains were introduced on molecular backbone, which modulated intermolecule and molecule-substrate interaction and controlled 2D structure. Based on the concept of the molecule engineering, we have designed and synthesized a series of Schiff base derivatives, and studied their structural features in two-dimensional(2D) and three-dimensional (3D) states by combining scanning tunneling microscopy (STM) and X-ray diffraction experiments. The Schiff-base derivatives with short alkyl chains crystallize easily, which allows a detailed structural analysis by X-ray diffraction. Due to the strong adsorbate-substrate interactions, those bases with long alkyl chains easily form 2D assemblies on highly oriented pyrolytic graphite (HOPG). The STM images indicate also that the introduction of two methoxy groups into the molecule can change the structure of these 2D assemblies as a result of the increased steric hindrances, for example: the Schiff-base derivative, bearing both methoxy groups and C16H33 tails, forms 2D Moire patterns, and an alignment of pairing Schiff-base molecules may be easily resolved. Conversely, the Schiff base derivative, bearing solely C16H33 tails, forms 2D non-Moire patterns. It is demonstrated that the 3D structural features result from the compromise of intermolecular interactions of different molecular moieties. However, there is one more factor, which also governs the 2D structure: the adsorbate-substrate interaction. The 3D crystal structure may thus help to understand many factors involved in the formation of 2D structures, and would be helpful for designing new molecular assemblies with tailoring functions. To further investigate the influence of steric hindrances, we studied the assemblies of N,N′-dialkyl-substituted quinacridone derivatives at liquid/solid interface. The experimental results indicate that the 2D structure can be controlled by introducing substituents and different length of alkyl chain. We also studied the 2D assemblies of the coadsorptions of quinacridone derivatives and fatty acid on HOPG observed by STM, and focused on how minor structural variations can influence the supramolecular organization of the compounds. For quinacridone derivatives with or without methyl groups only the same enantiotopic faces of the quinacridone cores are observed with high resolution depending on the length of the substituted alkyl chains. For coadsorptions of quinacridone derivatives and fatty acids at the liquid/graphite interface, we have found interestingly that quinacridone derivatives with methyl groups form chiral racemates, whereas the quinacridone derivative without methyl groups forms chiral domains. The chiral 2D structures formed at the interface are only observed when fatty acids are present as guest molecules and for quinacridone derivatives substituted with long更多还原