Thermal transformations of the supramolecular compound of cucurbit[8]uril with cobalt(III) complex {trans-[Co(en)2Cl2]@CB[8]}Cl•17 H2O

The thermal decomposition of hydrated cucurbit[8]uril C48H48N32O16 center dot 20H(2)O (CB[8]) and the inclusion compound of cucurbit[8]uril with cobalt(III) complex {trans-[Co(en)(2)Cl-2]@CB[8]}Cl center dot 17 H2O was studied in the inert atmosphere by TG, TM, and DSC methods. The dehydration of (C48H48N32O16)center dot 20H(2)O (at 320-390 K), and the decomposition of cucurbituril itself (at 620-720 K) are accompanied by a decrease in the sample volume. The inclusion compound loses water molecules at 320-380 K; dehydration is accompanied by an increase in the sample volume. The decomposition (pyrolisis) of the anhydrous compound takes place at 620-720 K; the decomposition is forestalled by a continued increase in the sample volume with an endothermic peak (490-600 K), and only the mass loss (620-720 K) is accompanied by a decrease in the sample volume. The included guest complex does not lose amines until the decomposition process is complete; the previously observed increase in the sample volume is explained by the expansion of cavitand molecules due to a distortion of the included [Co(en)(2)Cl-2](+) complex on heating.