The Crystal Structure of a New Form of β-Cyclodextrin Water Inclusion Compound and Thermal Properties of β-Cyclodextrin Inclusion Complexes

Abstract

Inclusion complexes of β-cyclodextrin (β-CyD) with water, methanol, ethanol, 1-propanol, p-iodoaniline, p-ethylaniline and 3, 4-xylidine have been studied by differential thermal analysis and differential scanning calorimetry and the results are discussed in relation to their crystal structures. It is found that (1) the difference in the packing mode of host β-CyD is reflected in the different thermal behaviour of the complexes in the temperature region between 25 and 140°C (Fig.1), (2) there are different forms of 8-CyDwater complex, namely from I and II in Table 1, (3) the form I shows a strong endothermic peak at 46°C, whereas the form II and other β-CyD inclusion complexes exhibit a few small peaks. X-Ray structure analyses applied to the two forms of β-CyDwater complexes elucidate that the form I is the same structure as determined by Lindner et al., whereas the form II shows a new structure and the structural difference between the form I and JI is found mainly at the distribution of disordered water molecules in the host β-CyD cavity as shown in Table 3 and Fig.6.