| Cyclodextrin (CD) is an cyclic oligosaccharides consisting of six or more glucose units connected byα-1,4 linkages. The three important CDs areα-,β- andγ-CD which are composed of 6, 7 and 8 glucose units respectively. They have a hollow truncated shape. As consequence of these structural features, CDs are capable of forming inclusion compounds with a variety of guests such as organic, inorganic and rare gas etc. In this thesis, we study the thermal behaviors ofβ-CD with some organic and organometallic guests by both experimental and theoretical methods. The main contents are as follows:1. The thermal decomposition behavior of survivedβ-cyclodextrin in its inclusion complex of clove oil is investigated by nonisothermal thermogravimetry (TG) analysis at the heating rates of 5.0, 10.0, 15.0, 20.0 and 25.0 K?min–1. The TG profiles based on mass loss as a function of temperature show a clear trend of increased thermal decomposition temperature with increased heating rate. Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) with a programmed temperature heating treatment is performed to experimentally investigate the relationship between procedural decomposition temperature and fragment composition of the sample. The results on the basis of fragment analysis explain the different mass loss of the sample corresponding to different temperatures on the gradient hot stage.2. Double extrapolation method was employed to determine the most probable mechanism function for the thermal decomposition reaction of the survivedβ-cyclodextrin (β-CD) from the inclusion complex ofβ-CD with clove oil. The curve of the activation energy (Ea) calculated from Flynn–Wall–Ozawa method was clearly divided into three stages for the thermal decomposition process of the survivedβ-CD. The nearly parallel linear relationship between first and last stages was assessed as Avrami–Erofe'ev A1.5 model. Furthermore, the platform in the second stage for the decomposition of the survivedβ-CD, in which each point has an approximately same value of Ea, was carefully investigated with the method of reaction order (n). Regulated decline of n with the increase of temperature implied the complicacy of the decomposition reaction mechanism of the survivedβ-CD in the stage. The infrared spectroscopic profiles during thermal decomposition between freeβ-CD and the survivedβ-CD were also compared. The change trend in IR spectra below 1000 cm–1 between freeβ-CD and survivedβ-CD are quite different, which was in good accordance with the calculated results of Ea values.3. Whether and how does a complexed organic guest change its thermal stability during heating process? Whether and how does the guest release influence the decomposition behavior of complexed host? In order to answer the questions, in situ Fourier transform infrared spectroscopy and gas chromatography coupled to time-of-flight mass spectrometry with programmed temperature were employed in the present work. The careful comparisons among the thermal decomposition behaviors of freeβ-cyclodextrin (β-CD) and its inclusion complexes of ethylenediamine and diethylenetriamine indicated that the release of the amines was not a simple physical process without the rupture of chemical bonds, but was instead a complex process together with the fragments from complexedβ-CD. In short, the release and decomposition of the complexed amines drove the decomposition of the complexedβ-CD in their respective inclusion complexes. It was found that the thermal decomposition behavior of the complexedβ-CD was influenced by the complexed amines dependent on the nature of the amines, and at the same timeβ-CD had, to a certain extent, changed the temperature of the phase-change, release and decomposition of organic amines by the formation of inclusion complexes with them.4. The second sphere interactions between ferrocene (Fc, guest) analogs and cyclodextrins (CD, host) have attracted sufficient attention in the past decades. However, there are many unanswered questions related with the interactions. For example, how such interactions are reflected by the thermal decomposition process of the formed inclusion complex Fc–CD? This question includes two aspects: 1) Whether Fc with a low sublimation temperature, when trapped in the cavity of a CD, can cause the change of the thermal behavior of the complexed CD with Fc? 2) Whether the flange portion of the CD cavity can provide a protective shield against the sublimation of Fc? The current work indicates that on the one hand, the presence of Fc effectively delayed the decomposition temperature of the complexedβ-CD though a great part of Fc had been released from the complex. On the other hand, the special molecular structure ofβ-CD has served to prevent the sublimation of Fc to a certain degree. Furthermore, the thermal decomposition mode of theβ-CD molecules complexed by Fc was drastically changed compared with that of freeβ-CD. Besides, scanning electron microscopy images at high temperatures were shown to give supportive evidence to such an interaction betweenβ-CD and Fc directly. And solid ultraviolet-visible absorption spectra revealed the effect of the presence ofβ-CD on the electronic transitions of Fc. Also, the results of X-Ray powder diffraction and two-dimensional nuclear magnetic resonance spectroscopy further demonstrated the intermolecular interaction between Fc andβ-CD.
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