Crystal structure of a new cyclomaltoheptaose hydrate: beta-cyclodextrin.7.5H2O.

The crystallographic study of a partially hydrated form of cyclomaltoheptaose (beta-cyclodextrin, betaCD) is reported. C(42)H(70)O(35).7.5H(2)O; space group P2(1) with unit cell constants a=15.1667(5), b=10.1850(3), c=20.9694(7)A, beta=110.993(2) degrees ; final discrepancy index R=0.0760 for the 6181 observed reflections and 784 refined parameters. One water molecule is included in the cavity and distributed over two partially occupied positions, the other 6.5 waters distributed over eight positions are located as space-filler between the macrocycles. The crystal structure belongs to the cage-type, like that observed in Form I (betaCD.12H(2)O; Lindner, K; Saenger, W. Carbohydr. Res. 1982, 99, 103-115) and Form II (betaCD.11H(2)O; Betzel, C., et al. J. Am. Chem. Soc., 1984, 106, 7545-7567).