The Supramolecular Gel System Based On Cyclodextrin

Molecular chemistry which is the chemistry researching the covalent bond, is concerned with mastering and uncovering the rules which govern the properties, structures, transformations of some molecular species. Supramolecular Chemistry focus on the supramolecular entities made up by more than two kinds of chemical species, such as molecules, ions, combining with each other through intermolecular forces. The low molecular mass gels which are based on the low molecular mass molecules are a typical kind of supramolecular gel. The low molecular mass gels are formed by low molecular mass gelators (LMMGs) through supramolecular forces to form the3D-network, which rely on interfacial tension and capillary force to entrap the solvent molecules and make the gel stable.So far, the main kinds of LMOGs are urea derivatives, amino acid derivatives, polysaccharide derivatives, cholesterol derivatives and organic gelators composed of organic and multi-components compound with composite structure. According to the different driving force, LMOGs can be divided into two classes:hydrogen bonding gelator and non-hydrogen bonding gelator. Urea derivatives, amino acid derivatives and polysaccharide derivatives all belong to the former, while the native cholesterol molecules can hardly form hydrogen bonding. P-cyclodextrins (β-CDs) are oligosaccharides composed of seven glucopyranose units bound by a-(1-4) linkages. P-CDs have an effective ability in forming of supramolecular gels constructed by inclusion complexes between the CDs and various organic compounds. In recent years, the organogel system based on cyclodextrins is more and more being concerned and there are some novel organogel systems have been discovered and designed.Based on the above ideas, this paper designed some novel organogel systems based on cyclodextrins and explored the mechanism of the gel’s formation. Firstly, the main research aspect in the gel system was focusing on the transformation between the non-solution phase to the gel phase. According to the gel and precipitation system, we do characterization and research as below:Scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR measurements (FT-IR). The new gel system has some features as below:(1) The system is composed of multi-components which are formed by simple small organic molecules. The components all play an important role in the gel and precipitate.(2) The transformation is induced by lithium chloride. Under some certain circumstance, the precipitate could transform to gel.(3) The system is different from common system and reverse thermal-response system. At normal temperature, the system kept clear solution, while after being heated, the precipitate would transform to gel which is called heat-set gel.(4) This system has for responsiveness to the amount of lithium chloride. When the amount of lithium chloride is less than the needed, the precipitate could not transform to the gel completely and still keep precipitation state. Only the amount of lithium chloride reached a certain value, the precipitation can transform into gel.