Synthesis And Application Of Cucurbit[6] Uril And Its Derivatives

As the "fourth generation supermolecule compound", cucurbituril is characterized with its special structure of hydrophobic cavity and hydrophilic outlet, which thus provide its distinguished supermolecular inclusion interaction for metal ions, organic molecules and neutral molecules, and it has displayed great potential applications in molecular recognition, sewage treatment, biomimetic enzyme, molecular assembly, clinical medicine and etc. The research history of cucurbituril was not so long as other supermolecules, it is becoming to be popular after 1987, and so far much relative research is still in the starting stage. In this thesis, the mechanism of inclusion interaction between cucurbit[6]uril (CB[6]), perhydroxycucurbit[6]uril (HOCB[6]) and teracthlorofluorescein (TSS) has been studied, which will be helpful to understand the inclusion behavior of cucurbit[6]uril. Recently, magnetic materials are attracting more and more attention because of their advantage of easily recycling. Herein we proposed to graft cucurbit[6]uril on the surface of SiO2-Fe3O4 adsorb core-shell magnetic nanoparticles, and use it as a ligand to adsorb amino acids, this is a totally interdisplinary research of analytical chemistry, materials chemistry and supermolecular chemistry, which will benefit for the expansion of cucurbituril's application in separation science. In addition, the study on the adsorption and desorption properties of the obtained magnetic nanoparticles for amino acids will also provide a theory basis in the clinical medicine.In this paper, glycoluril was synthesized with urea and formaldehyde with reported method, and then it was used for the preparation of cucurbituril under acid condition. The obtained cucurbituril was a mixture of CB[5],CB[6], CB[7] and CB[8], in order to get purified CB[6], multiple steps has been adopt according to their different solubility in the water, acetone and hydrochloric acid. Furthermore, the prepared CB[6] was then oxidized with K2S2O8 to prepare HOCB[6] by the introducing hydroxyl group at the waist of CB[6]. The FTIR and elemental analysis results of CB[6] and HOCB[6] were coincide with Sadtler standard spectra and reported patterns.The inclusion interaction between HOCB[6] and TSS was studied by fluorimetric methods. Several effect factors, such as the concentration of HOCB[6], pH values, temperature, inclusion time and common organic solvents on the fluorescence intensity and the stability of the complex were investigated. The results indicate the emission peak of TSS appears a little blue shift and there is an obvious fluorescence enhancement along with the introduction of HOCB [6], The results obtained from the method Hildebrand-Benesi prove that the 1:1 type inclusion complex was formed between HOCB [6] and TSS, and the thermodynamic parameters of inclusion reaction indicate that the inclusion process is a spontaneous exothermic process, which was mainly caused by the hydrophobic interaction and ion-dipole interaction between the host and guest molecules.In order to functionalize the surface of SiO2-Fe3O4 core-shell magnetic nanoparticles with cucurbit[6]uril, superparamagnetic nanoparticles were firstly prepared with hydrothermal method, and then it was coated with SiO2 to form a typical SiO2-Fe3O4 core-shell magnetic nanoparticles, the obtained core-shell magnetic nanoparticles was further modified with HOCB [6] by using (3-isocyanatopropyl)triethoxysilane as a spacer arm. The cucurbit[6]uril functionalized magnetic nanoparticles were characterized by means of such test instruments as IR, XRD, SEM, BET and VSM, etc. The saturation magnetization of HOCB[6]-SiO2-Fe3O4 is 17.6 emu.g-1, specific surface area is 136.65316 m2.g-1. The good magnetic properties and large surface area indicate its great potential in the separation area.The absorptivity of SiO2-Fe3O4 and HOCB[6]-SiO2-Fe3O4 for three different basic amino acid, such as Arg, Lys, His, has been studied under different pH values, the results showed that three basic amino acids could be obviously adsorbed by HOCB [6]-SiO2-Fe3O4. The adsorptive capacity of HOCB[6]-SiO2-Fe3O4 is approximately 1.5～2.15 times of SiO2-Fe3O4. All of the three amino acid adsorbed by SiO2-Fe3O4 could be desorbed completely, but as for HOCB[6]-SiO2-Fe3O4, only His can be fully desorbed, Lys and Arg can only partialy desorbed. It was assumed that electrostatic interaction played an important role for SiO2-Fe3O4 to adsorb amino acid, but for HOCB[6]-SiO2-Fe3O4, the inclusion interaction between amino acids and HOCB[6] probably lead to the difference of the desorption for the three amino acids.