A comparative study on the thermal decomposition behaviors between beta-cyclodextrin and its inclusion complexes of organic amines.

How does a complexed organic guest change its thermal stability during the heating process? How does the guest release influence the decomposition behavior of the complexed host? To answer these 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 free beta-cyclodextrin (beta-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 complexed beta-CD. In short, the release and decomposition of the complexed amines drove the decomposition of the complexed beta-CD in their respective inclusion complexes. It was found that the thermal decomposition behavior of the complexed beta-CD was influenced by the complexed amines dependent on the nature of the amines, and at the same time, beta-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.