| Halogen bonding is a type of weak interaction between the halogen atoms (electron acceptor) and electron-donating atoms or groups. It is very analogous to hydrogen bonding and have attracted extensive attention in recent years. Based on previous work of our research group, this dissertation was devoted to explore the applications of halogen bonding in molecular recognition, crystal engineering and chemical catalysis. It falls into five chapters:In the first chapter, a simple history of the discovery and development of the concept of halogen bonding was firstly introduced, then the applications of this type of weak interaction in molecular recognition, crystal engineering, drug and material design, chemical catalysis etc. were reviewed.In the second chapter, the feasibility of using ultraviolet (UV) spectroscopy method in the study of halogen bonding was explored. Firstly, some complexes containing I...N and I...O halogen bonding were established by solution synthesis technique. Then, we investigated the changes of the UV spectroscopy upon the formation of the complexes. It had been indicated that, for the halogen-bonded systems, there were obvious red or blue shifting of the UV absorption as compared with the corresponding monomer systems, the maximum red and blue shifting reached to15nm and25nm, respectively. However, it seemed no quantitative relationship between the strength of halogen bonding and the change of UV absorption.The third chapter was devoted to explore the effect of metal ion coordination to the halogen bonding. For this purpose, three single crystals of inorganic-organic hybrid complexes (C10H8Cl4N2Zn, C10H8Cl2Br2N2Zn, and C10H8Cl2I2Zn) formed by3-chloropyridine and ZnX2(X=Cl, Br, I) were obtained, and their X-ray diffracted crystal structures were determined. It can be seen from the results that:(1) all the Zinc atoms posses slightly distorted tetrahedron structures. For the complex C10H8Cl2I2N2Zn, the relative position of the chlorine atoms in the two pyridine rings is different to those in the other two complexes, which leads to that the three crystals belong to different crystal system and space group (triclinic system, P-1space group for C10H8Cl4N2Zn and C10H8Cl2Br2Zn, and Orthorhombic system, Pcab space group for C10H8Cl2I2N2Zn).(2) C-Cl...Cl-C halogen bonds are found in all three complexes, and the halogen bond strength decreases in the order ZnCl2, ZnBr2, ZnI2.(3) for the complexes C10H8Cl2Br2N2Zn and C10H8Cl2I2NaZn, there also exist Zn-X. Cl-C halogen bond interactions, whereas for C10H8Cl4NaZn, similar interaction is not observed.In the fourth chapter, we explored further the reactions of indole and carbonyl compounds catalyzed by iodine on the basis of previous work. The catalyst iodine was firstly loaded on the activated carbon, and the reaction of indole with benzaldehyde catalyzed by iodine was performed through transforming the homogeneous catalyst to heterogeneous catalyst. The effects of reaction time, reaction temperature, solvent, the amount of catalyst and the recycle times to the reaction were investigated. It has been shown that in certain condition, the reaction can be catalyzed very well, but the reusability of the iodine remains to be further improved.In the last chapter, the contents of the whole dissertation were summarized, and the prospect of the applications of halogen bonding was put forward. |
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