The Structure of the Cyclodextrin Complex. VII. The Crystal Structure of the α-Cyclodextrin–DMSO–Methanol(1 : 1 : 2) Dihydrate Complex A Simultaneous Inclusion of DMSO and Methanol

Abstract

Abstract The crystal structure of the α-cyclodextrin(α-CDx)–DMSO–methanol (1 : 1 : 2) dihydrate complex was determined by the X-ray method. The crystal is monoclinic, and the space group is P21 with Z=2. The cell dimensions are a=9.505(1), b=14.150(1), c=19.738(2) Å, and β=102.88(1)°. The structure was solved by an inspection of a Patterson map and by a trial-and-error method, and was refined by the block-diagonal least-squares method to the final R-value of 0.083 for 3732 reflections. The α-CDx ring is nearly hexagonal, with diagonal distances of 8.40–8.53 Å between the glycosidic oxygen atoms. The α-CDx molecules are arranged to form molecular layers perpendicular to the ac plane. The DMSO molecule is located on the secondary hydroxyl side in the α-CDx cavity, forming two hydrogen bonds with the adjacent α-CDx molecules. One methanol molecule is found on the primary hydroxyl side in the cavity, while the other is located outside the cavity. Two water molecules are distributed in the space between α-CDx molecules.