新型二茂铁双胆固醇衍生物的合成及其胶凝行为

【作者】 何盼丽；

【导师】 房喻；

【作者基本信息】 陕西师范大学 ， 物理化学， 2010， 硕士

【摘要】 近年来,基于小分子化合物的有机凝胶受到日益广泛的关注,这不仅仅是因为它们能够通过分子间弱相互作用自组装成丰富多样的超分子结构,更是因为它们本身就是性质独特的软物质材料。小分子凝胶属于物理凝胶,其形成主要依靠氢键、范德华力、π-π堆积、静电、配位、疏溶剂以及偶极－偶极等弱相互作用,因而往往具有良好的热可逆性。而一些特殊功能基团的引入可使其具有更加优良的性质,如对外界光、电、主客体、氧化还原以及剪切力等的刺激响应,因而小分子凝胶在传感器、药物缓释、模板合成、文物保护、水处理以及油水分离等方面都具有潜在的应用价值。胆固醇分子具有刚性骨架、多手性中心,易于通过范德华作用发生簇集,其衍生物往往表现出良好的胶凝能力,是一类常见的小分子胶凝剂。二茂铁所具有的磁性、催化特性、电活性以及非线性光学等性质使其衍生物在催化、分子电子器件、非线性光学材料、传感器等方面显示出很好的应用前景。本学位论文立足本实验室已有的工作基础,将二茂铁置于双胆固醇结构连接臂的侧链位置,设计合成了LS2型(L代表连接臂,S代表胆甾基)的双胆型小分子有机胶凝剂,并对其形成的凝胶进行了深入的研究,同时还获得了油包水型(W/O)L凝胶乳液。本学位论文主要包括以下两部分内容：第一部分：通过改变连接臂上氢键结合位点的数目,设计合成了3种以二茂铁为侧链的双胆固醇型化合物(分别是1,2,3)。利用1HNMR、FT-IR和元素分析对这三种化合物的组成和结构进行了表征,并系统考察了这三种化合物在常见有机溶剂中的胶凝行为。发现化合物1不能胶凝所测试的34种溶剂,化合物2可以使正己烷、正庚烷、正辛烷、正壬烷、正癸烷以及环己烷胶凝化,而化合物3则只可以使DMSO和环己烷胶凝。其中,2／正癸烷体系具有多重刺激响应性(图1)。利用红外、核磁以及X射线衍射等手段探讨了凝胶的形成机理,观察了部分凝胶网络的微观结构,推测了凝胶形成基本过程,提出了化合物2在正癸烷中的簇集体模型。第二部分：在第一部分工作基础上,以化合物2为稳定剂制备了含水量(分散相)可达97%(v/v)的2/正癸烷／水凝胶乳液,研究了含水量对该体系相行为的影响。光学显微镜观察表明体系是典型的凝胶乳液泡沫结构。流变学研究表明,2/正癸烷/水凝胶乳液具有良好的力学稳定性以及凝胶类物质所拥有的典型的粘弹性,而且凝胶乳液的储能模量G′和屈服应力都随着分散相体积分数增加而增加,这一结果与文献报道一致。同时,还发现2/甲基丙烯酸叔丁酯/水凝胶乳液体系,通过自由基引发聚合的方法得到了多孔结构的低密度聚合物材料(图2)。更多还原

【Abstract】 Recently, increasing interest has been paid to organogels based on low-molecular-mass compounds. This is not only because various superamolecular networks can be formed due to self-assembly of the gelator molecules in the medium, but also because they are soft materials with special properties. Low-molecular-mass gels belong to physical gels and they are formed and maintained by weak interactions including hydrogen bonding, van der Waals interactions,π-πstacking, electrostatic interactions, coordination interactions, and dipole-dipole interactions, ect. Therfore, these systems usually possess better thermo-reversibility. Furthermore, introduction of some functional groups in low-molecular-mass gelators may result in stimulus-responsive properties, in which the stimuli can be irradiation, electron or charge transfer, host-guest interaction, oxidative/reductive reaction, and shearing force, etc. It is because of these reasons that low-molecular-mass gels have promising potential applications in sensors and actuators, drug delivery, protection of historical relics, as templates for preparing micro/nano-materials, oil recovery, mild separation and purification, etc.It is known that cholesterol possesses a rigid skeleton, several sterogenic centers, and a strong tendency to form aggregates via van der Waals interaction. These structural characteristics make it an ideal component for designing various potential low-molecular-mass organic gelators (LMOGs) and in fact cholesteryl derivatives are efficient LMOGs. Ferrocene (Fc), a typical organometallic compound, possesses cataytic, magnetic, electrical activity and nonlinear optical properties., As a result, its derivatives have been widly applied in asymmetric catalysis, in the development of molecular electronic materials, in light stabilizer, electrochemical sensor, etc. As the continuation of our work on the studies of LMOGs, Fc has been intentionally introduced into three specially designed LS2 type di-cholesteryl derivatives as a pendant structure, where L denotes a linker and S stands for a steroidal unit. Their gelation behaviors are investigated and water-in-oil (W/O) gel-emulsions have been obtained. This distation is maily composed of the follow ing two parts:In the frist part, three compounds denoted as 1,2, and 3, respectively, are designed and sytheszied by varying the number of hydrogen-bonding sites in the linkers. The structures and compositions of all these compounds are characterized by 1H NMR, FT-IR spectroscopy, elemental analysis, and satisfied results have been obtained. The gelation properties of the three compounds in common solvents are studied systematically. It is found that that 1 gels none of the 34 solvents tested, 2 gels some of the alkanes, and 3 gels only cyclohexane and DMSO. Importantly, the gel system of 2/n-decane exhibits a sol-gel phase transition upon thermal, ultrasonic, mechanical or even chemical treatments (Fig.1). The micro-morphologies of some xerogels are investigated by SEM. Concentration dependent of the morphology of the xerogel was also intentionally investigated in order to examine the evolution process of the microstructures of the xerogels. FT-IR、XRD and 1H NMR studies revealed the formation mechanism of the organogel. At last, a structural mode has been proposed to describe the fundamental assembly of 2 in n-decane.In the second part, compound 2 as a stabilizer was used to prepare the water in oil gel emulsion as a continuation of the frist part. Frist, the systems of 2/n-decane/water with different water contents were adopted as example systems to look for the effect of the water content on phase behavior. For the system of 2/n-decane/water, the maximum volume ratio of water (dispersed phase) is 97%(v/v). Optical microscopy measurements confirmed the foam-like structures of the gel emulsions. Rheological measurements demonstrated that the 2/n-decane/water gel emulsions possess good mechanical stability, and exhibit typical viscoelastic properties. It was found that the storage modulus (G’) and the yield stress of the gel emulsions increase along with increasing the volume ratio of the dispersed phase, a result consistent with the result of the traditional gel emulsions. At the same time, the system of 2/tert-butyl methacrylate/water gel emulsion was created (Fig.2). Tert-butyl methacrylate was successfully polymerized by free redical polymerization in this gel emulsion to get porous and low-density material (Fig.2).更多还原