【作者】 刘佳伟；

【导师】 马建泰； 陈传峰；

【作者基本信息】 兰州大学 ， 物理化学， 2010， 博士

【摘要】 有机小分子凝胶是指小分子有机化合物在很低浓度下通过分子间作用力(氢键作用等)聚集、自组装形成延伸的纤维状聚集体,并进一步形成包裹液体介质的三维网络结构使液体介质凝胶化。近年来,由于有机小分子凝胶具有独特的结构以及其在作为模板合成无机纳米材料、采油,有机软性材料,光学传感器,药物的缓释系统等方面的广泛应用,所以在材料科学和超分子化学领域,有机小分子凝胶的研究受到了越来越多的关注。最近,由于具有巨大的潜在应用价值,发展“智能”或“响应”有机小分子凝胶特别具有吸引力。因此一些通过外界刺激(例如光、离子强度、电场或磁场、酸碱变化、分子识别、以及超声波刺激等)来实现凝胶和溶液之间的相互转化已经被报导。超分子凝胶通过外界刺激可以可逆变化的性质为利用刺激可控催化体系提供了基础。本文的主要内容：1基于酰肼、蒽醌的小分子有机凝胶因子的合成以及其有机凝胶体系的研究我们合成了一类基于酰肼、蒽醌、烷基长链的新型凝胶因子1b-1e。研究了分子结构和成胶性质之间的关系。凝胶因子1b-1e能够使多种有机溶剂形成稳定的凝胶,最低成胶浓度可以达到0.1wt%。我们发现在氯仿和芳烃溶剂中形成透明的有机凝胶,而在醇类和其他溶剂中则形成不透明的凝胶。更为重要的是,1c这种非手性分子可以在乙醇中自组装形成手性的螺旋结构。通过FT-IR、PXRD、Uv-vis和1HNMR研究我们得出结论：分子间的氢键作用以及蒽醌之间的π-π堆积作用是形成凝胶的主要驱动力。2凝胶体系的多重响应性及其应用(1)酸碱调控氢键作用在成胶过程中起着重要作用.通过加入三氟乙酸破坏分子间的氢键作用可以实现凝胶到溶液的转换,再加入三乙胺可以再回到凝胶状态.(2)阴离子响应尽管这种凝胶因子中生色团蒽醌和氢键单元通过σ键相连,但是氯仿凝胶能够对特定的阴离子做出双重响应：凝胶到溶液的转化和颜色的变化.由于这种响应的根本原因是脱质子化作用,所以加入甲醇后能够使颜色变化消失并且实现由溶液到凝胶的转化.(3)超声响应虽然凝胶因子1c-1e在DMSO以及甲醇等强极性有机溶剂中不能形成有机凝胶,但是在他们的热溶液冷却时用超声波进行刺激则可以形成稳定的凝胶。并且超声波刺激可以极大改变凝胶的形貌。(4)有机凝胶的应用凝胶因子1b-1e可以在水和有机溶剂的混合物中选择性的使有机溶剂凝胶化。另外,通过有机凝胶制备的干凝胶可以从水溶液中吸附甲基紫等染料分子。这种凝胶因子的染料吸附能力可以用于水的纯化。更多还原

【Abstract】 Organogels are composed of a self-assembled suprastructure of low molecular-mass organic gelators (LMOGs) through weak intermolecular interactions (such as hydrogen bonds etc) and a large volume of liquid immobilized therein. Because of their unique structures and wide applications in templated synthesis of nano-scale inorganic materials, oil recovery, organic soft materials, optical sensors, slow drug-delivery systems and so on, studies on organogels have been the subject of increasing attention in materials science and supramolecular chemistry in recent years. Recently, the development of "smart" or "responsive" gels has been especially appealing for potential applications. Thus, some examples on the sol-gel transition tuned by the environmental stimuli, such as light, ionic strength, electric or magnetic fields, mechanical stress, pH changes, molecular recognition and ultrasound have been reported.The reversible nature of supramolecular gels seems ideal for the use of stimulus-controlled catalytic systems by environmental stimuli.This paper contains the following sections:1 The synthesis of small molecule organic gels factor based on hydrazine, anthraquinone and study of its organic gel systemThe novel low-molecular-weight organogelators(LMOGs) lb-le composed of an anthraquinone unit, a hydrazide group, and long alkyl chains were synthesized. Studies on their structure-property relationship are intensified. They could form stable gels at concentrations as low as 0.1 wt% in tested solvents. Chloroalkanes and aromatic solvents tend to result in transparent gels, while alcohol and other solvents yield opaque gels. Interestingly, we further found that the achiral gelator could form supramolecular structures with well-defined helical ribbons. The FT-IR, PXRD, Uv-vis and 1H NMR spectral studies revealed that hydrogen bonding andπ-πinteractions were the main driving forces for formation of the gels. 2 This gel system of multi-responsive and its application:(1) Acid and Alkali Responsive PropertiesThe intermolecular hydrogen bond plays an important role in the forming gel process. By adding the TFA to the gel, the intermolecular hydrogen bonds can be damaged leading to the conversion of gel to the solution, and then adding TEA can return to gel state.(2) Anion Responsive PropertiesAlthough the hydrazide unit and the anthraquinone group were connected by the a-bond, the chloroform gel of lc could be changed into a red solution upon the addition of anion (F-, AcO- and H2PO4-) due to the disruption of the intermolecular hydrogen-bondings. Moreover, the red color clearly faded at once and the solution re-gelated upon the addition of methanol.(3) Ultrasound Responsive PropertiesAlthough compounds lc-le could not form gels in strong polar solvents, such as DMSO, methanol etc, Ultrasound promotes lc-le to form organogels when cooling its hot solution. The morphologies of the xerogels prepared from these gelators are strongly affected by ultrasound stimuli.(4) The application of organogelsThese organogelators could selectively gelate organic solvents from their mixtures with water. Furthermore, the xerogels prepared from the organogels showed a striking property of adsorbing dyes such as crystal violet from water. This dye-adsorption ability of gelators can be utilized in water purification by removing toxic dyes from wastewater.更多还原