THERMOLYSIS OF BETA-CYCLODEXTRIN ALKYLCOBALOXIME INCLUSION COMPLEXES IN THE SOLID-STATE/

The solid state stability of a series of beta-cyclodextrin/alkylcobalo xime inclusion complexes has been investigated by differential scannin g calorimetery (DSC) and thermogravimetric analysis (TGA). Four distin ct transitions in the TGA scans, corresponding to dehydration (Tc1), d ealkylation (Tc2), breakdown of equatorial oxime ligands (Tc3), and de composition of beta-CD (Tc4) were generally seen. Three distinct trans itions during DSC, corresponding to Tc1 (endotherm), Tc2 (exotherm) an d Tc4 (endotherm), were observed in most cases. In addition, the tempe ratures of dealkylation were higher in beta-cyclodextrin/alkylcobaloxi me complexes than those of the corresponding alkylcobaloximes. The Tc2 changes were related to the substitution groups on the alkylcobaloxim es and paralleled the stability constants of these inclusion complexes . (C) 1997 Elsevier Science B.V.