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Novel supramolecular reversible system response studies

Author: LiJianYe
Tutor: HaoAiYou
School: Shandong University
Course: Organic Chemistry
Keywords: Cyclodextrin Molecular Recognition Response Reversible Crystals
CLC: O636.12
Type: PhD thesis
Year: 2010
Downloads: 211
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Abstract

Its unique hydrophobic cyclodextrin cavity structure, good biocompatibility, modification of the materials, medicine, catalysis, analytical and other various fields more and more widely. Cyclodextrin is one of the most important properties and the role of guest molecules through the formation of supramolecular inclusion. Cyclodextrin as host molecules and guest molecules cooperate with the package, there are two ways: one is inside the inclusion (endo-recognition), the main force of van der Waals, hydrophobic interaction, etc.; Another is outsourcing together (exo- recognition), the force is mainly hydrogen bonds. In supramolecular effects, often of several forces together, the relative magnitude of each force the reaction medium, temperature and the guest molecule size, shape, polarity, the number of substituents on such factors as the nature . Wherein the solvent and temperature effects in supramolecular unavoidable factors, research solvents and temperature on the role of supramolecular supramolecular us investigate the mechanism of action targeted selection of reaction conditions have important guiding significance . This thesis consists of five parts, as follows: First, the temperature-induced β-CD/DMF / organic molecular systems reversible precipitation - dissolution behavior of one, reported the p-CD in DMF solvent dissolution anomalous phenomena. Right β-CD/DMF / anomalous precipitation behavior of organic molecular systems were studied, this system is a clear solution temperature, high temperature will precipitate. Temperature and precipitation structure of the guest molecule. Variable temperature infrared absorption spectrum detected in β-CD/DMF/α- naphthol system, host-guest molecules, host-guest molecules and hydrogen bonds between the solvent molecules and hydrogen bond strength and mode of action with temperature the rise of change. Testing shows that in the heating process, p-CD secondary hydroxyl hydrogen bonding molecules change. When the temperature, p-CD molecules adjacent C-2 and C-3 hydroxyl group to form intramolecular hydrogen bonds. When the temperature rises above 65 ℃, p-CD intramolecular hydrogen bonds broken, when heated to above 95 ℃, β-CD molecule C-2 and C-3 hydroxyl groups and can form intermolecular hydrogen bonds between the molecules hydrogen bonds formed such p-CD precipitated polymer molecules. 2, through the p-CD / organic molecule / DMF three-component system for 1H NMR, ROESY, variable temperature infrared, variable temperature NMR, variable temperature circular dichroism, UV, GC, XRD, and many other representation, found in DMF, p -CD together with the organic molecules to outsource model, rather than entering the cyclodextrin cavity to form inclusion complexes. Supramolecular hydrogen bond is its role in the main mode. The primary mode of action of guest molecules in other solvents significantly different. Variable Temperature Infrared absorption spectroscopy showed that the guest molecule α-naphthol with p-CD molecules forming supramolecular complexes outsourcing aggregate at high temperature dissociation occurs. Combined with infrared spectroscopy and XRD characterization results, etc., in order to prove that precipitated as a combination of intermolecular hydrogen bonds β-CD. Second, the salt effect on β-CD/DMF / impact of an organic molecular systems, such as discussed LiCl salt P-CD/DMF / organic molecular systems affected. LiCl can β-CD/DMF / organic systems settling temperature, under certain conditions, gel formation system. The gel system is a new type of thermally induced reversible gel system. 2, the main object ratio, LiCl concentration of the gel systems were studied. Third, the medium effect and maternal β-CD new polymorphs 1, training obtained maternal p-CD hydrate new crystal types: p-CD-7.5H2O (Form Ⅲ). 2, Form Ⅲ with two known maternal β-CD hydrate crystal structure has similarities: three crystal is isomorphous type (isomorphous), belong to the same space group P21. Adjacent glucose residues within the system of intramolecular hydrogen bonds between the O-2 ...... 0-3 on p-CD macrocyclic molecules play a stabilizing role, so that the formation of a macrocyclic ring opening, in which O- 4 at approximate coplanar. In the crystal lattice, p-CD molecules are stacked fish bone, different number of water molecules in the large space between the rings as a fill. With Form Ⅰ and Form Ⅱ is different, Form Ⅲ molecular unit whose cavity has only one water molecule, considerably less than the Form Ⅰ and Form Ⅱ. This phenomenon helps to explain the different conditions cyclodextrin properties and catalytic properties. Fourth, the temperature-induced mono-substituted cyclodextrin derivatives \)-β-CD, and apply variable-temperature NMR, IR variable temperature, variable temperature circular dichroism and other means to detect the heating process, a single - (6 - benzoyl-ethylamine-6 - deoxy)-β-CD in DMF molecules Structural changes with temperature. Detected, in DMF, single - (6 - benzoyl-ethylamine-6 - deoxy)-β-CD taken from the inclusion mode, which is different from the mode of self-assembly in water; at about 65 ℃, Single - (6 - ethylamine benzoyl-6 - deoxy)-β-CD molecule substituted phenyl group gradually shifted cyclodextrin cavity, since the clathrate structure gradually dissociated. V. Preliminary cyclodextrin catalytic Beirut reaction to p-CD as catalyst Beirut reactions. The reaction with water as solvent, at room temperature, the reaction rate is fast and high yield, compared with the traditional process has improved greatly.

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