【作者】 李研；

【导师】 巨勇； 李广涛；

【作者基本信息】 清华大学 ， 化学， 2009， 博士

【摘要】 胆甾酸类化合物来源于生物体,以其鲜明的结构特征,活泼的化学反应性和低廉的价格成为超分子化学中的重要研究对象。本论文围绕胆甾酸衍生物这一主题,充分利用胆甾酸独特的分子结构,设计合成了一系列新型二聚胆甾酸衍生物和含有胆甾酸基团的共轭高分子,研究它们的生物活性构效关系,溶液中构象调控以及超分子组装行为,取得了以下研究结果:设计合成了9种氨基酸桥联的二聚胆甾酸衍生物,通过染料包裹实验研究了这类化合物在非极性溶剂中的空间构象。生物活性筛选显示部分化合物对乳腺癌细胞MCF-7具有细胞毒活性,其中带有较少取代基的疏水连接臂和含有羟基较多的二聚胆酸缀合物细胞毒效果更为显著。首次合成一系列新颖的偶氮苯桥联二聚胆甾酸衍生物。由于胆甾酸中羟基与溶剂分子之间的氢键作用,溶剂和化合物结构差异都对光异构化速率有显著影响。利用偶氮苯的光致顺反异构特性并结合体外抑制大肠杆菌的筛选实验,初步建立了这类二聚胆甾酸衍生物的生物活性构效关系。研究了偶氮苯和寡聚对苯撑乙炔两类共轭体系桥联二聚胆甾酸衍生物的超分子组装行为。发现在四氢呋喃和水的混合溶液中,对苯撑乙炔桥联二聚去氧胆酸依靠氢键,π-π堆积和疏水作用力形成了一种非常独特的手性条带状聚集体。组装条件和化合物结构的微小差异都会对超分子组装的形貌产生显著影响。首次合成带有面式双亲性胆甾基团的共轭高分子,研究了它们溶致变色和组装特性。发现含有胆酸侧基的聚对苯撑乙炔具有显著的溶致变色效应和良好的生物相容性;在胆甾基团诱导下,聚合物可以在不同极性溶剂中组装成实心微球和空心囊泡等纳米超分子结构,表明胆甾酸基团可以有效调控共轭体系的聚集状态。尝试用电化学方法合成含胆甾基团共轭高分子。利用“Click反应”修饰聚吡咯,实现了包括胆甾酸在内的多种生物分子在电极表面的固定。更多还原

【Abstract】 Bile acid is a class of natural occurring compounds, with a rigid hydrophobic backbone, a curved profile and facially amphiphilic characteristic. Due to its unique structure, bile acid has been presented as one of the most important platforms for the construction of functional supramolecular system. In this dissertation, we focused on the design and synthesis of a series of novel dimeric bile acid derivatives and bile acid derived conjugated polymers. Their structures were identified by means of spectroscopic methods, the preliminary bioactivity was screened and their conformation in solvents as well as their self-assembly properties were studied. The major work is as follow:Nine dimeric bile acid conjugates linked by amino acid moieties have been synthesized in a facile way and their unique amphiphilic conformation was confirmed by dye extraction experiment. The compounds show modest antiproliferative activity against MCF-7 cancer. Dimeric cholic acid linked by a hydrophobic linker exhibits the more significant cytotoxic activity.A series of dimeric bile acids linked by 4, 4’-diaminoazobenzene were synthesized. The process of trans-cis photoisomerization, which was sensitive to the molecular structure and solvent used, was considerably slow due to the large and rigid skeleton of bile acid. Depending on the trans-cis photoisomerization of azobenzene moiety, the structure-activity relationship of these dimeric bile acid derivatives was preliminarily established. When these bile acid dimers adopt a cis configuration, a more significant antibacterial activity against E. coli DH5αcan be observed.The self-assembly behavior of bile acid dimers linked by conjugated moieties, including azobenzene and oligo(p-phenyleneethynylene), were studied. In the case of oligo(p-phenyleneethylene) bearing dimeric deoxycholic acid end groups, the addition of water to THF can lead to a highly interesting twist assemblies, which is the result from the combination of hydrogen bonding,π-πstacking and hydrophobic interaction. Varying the kinds of bile acid led to nanostructures with drastically different morphologies.A series of novel bile acid decorated poly(p-phenyleneethynylene) have been synthesized. The facially amphiphilic property of bile acid can increase the biocompatibility and endow remarkable solvatochromism to the conjugated system. Moreover, the cholate group can mediate the organization of PPE backbone and afford nano-scale assemblies with adjustable size and morphology.We have attempted to obtain bile acid functionalized conjugated polymers by electropolymerization.“Click”chemistry, specifically Huisgen 1, 3-dipolar cycloadditions, was used as a general methodology for the functionalization of the formed polypyrrole films on electrodes. Several bioactive compounds, including bile acid, nucleic acid and protein can be bound onto the electrode surfaces without the loss of their functionality and the electroactivity of the underlying conducting polymers.更多还原