| 1. Synthesis and Characterization of Inclusion Complex of 4-(2-Pyridylazo)resorcinol with β-CyclodextrinThe inclusion complex of β-cyclodextrin (p-CD) with 4-(2-pyridylazo)resorcinol (PAR) has been synthesized. It has been characterized by UV-vis spectroscopy, FT-IR, and powder X-ray diffractometry. Utilizing the solubilizing effect of P-CD on PAR, the effect of P-CD solution on elution of PAR from zeolite comparing to water was studied. The results indicate that a the ratio of host to guest in the inclusion complex is 2:1, which means that PAR molecule is enwrapped from both ends by the hydrophobic cavitys of two p-CDs. At 25 ℃, the dissociated constant, KD, of the inclusion complex is 3.5×10-6mol dm-3; and comparing to water, β-CD aqueous solution is the more effective in eluting PAR.2. Synthesis and Characterization of Mono-6-Thiol-β-CD(I) and I-Modified Colloidal GoldMetal nanoparticles stabilized by thiol molecules has become a charming area of interdisciplinary research in recent years. As a representive of the supermolecular host compounds, CD bears well-defined molecular recognition abilities. Because the properties of metal colloidal particles can be affected or even controlled by the surface-attacheded ligands, the CD derivatives can not only be modified on metal particles but also control particle assembly through well-known molecular recognition,which makes this nanocomposite system processing the best features of two worlds: the electronic, magnetic, and/or catalytic properties of the metal cores with the molecular recognition ability of the protecting organic monolayers.Recently, Liu et al have reported the modification of gold, platinum, palladium nanoparticles with perthiolated CD(CD-SH). At present, however, the research work on taking CD derivatives as ligands is focused on the attachment of CD-SH on metal nanoparticle surfaces. Propably because monothiolated CD was found to be less efficient than CD-SH. Therefore, there are only few reports about monoithiolated CD modified metal nanoparticles. But the synthesis of monothiolated CD is more facile than CD-SH which is also less stable, and the tropism of surface-attached monothiolated CD will be more random. In this chapter, we adopted a two-step approach to synthesize I, a derivative of β-CD. The product was characterized by FT-IR, powder X-ray diffractometry and NMR. Then the adsorption of I has been studied for different-sized gold nanoparticles in different temperature and various concentration of I, with mean diameters of 10, 18, and 42nm, using UV-vis spectroscopy and TEM. And the influence of I on the monodisperse and spectral behavior of colloidal gold has been discussed. What's more, we adopted the method reported by Liu et al and made some improvement for preparing I-modified gold nanoparticles. The experiment results show those particles are stable, water-soluable and ~7nm in diameter.3. Host-guest Interaction at the Surface of Gold NanoparticlesSelf-assembly of nanoparticles and nolecules to form complex nanostructures in solution is an important object of modern materials chemistry. The major limitation in nanoparticle-based materials chemistry is the lack of suitable assembly methods for preparing extended two- or three-dimensional architectures.The surface of the CD molecule is hydrophilic, while the cavity is relativelyhydrophobic. Owing to their structural characteristics, CDs are capable of forming inclusion complexes with a variety of guest molecules by incorporating them within their hydrophobic cavities. Specifically, can I-capped gold nanoparticles serve as mulsite receptors for host-guest complexation?In chapter 4, we used PAR and methyl green(MG) as guests to study the host-guest interaction at gold nanoparticle surfaces. By using TEM, we has proved this new type of nanocomposite may act as a very useful building block of the construction of nanoscale architectures in aqueous solution. Furthermore, the host-guest interaction between nitrobenzene, guest, and I-modified gold nanoparticles has been characterized b... |
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