CRYSTAL-STRUCTURE OF 6-0-[(R)-2-HYDROXYPROPYL]CYCLOMALTOHEPTAOSE AND 6-0-[(S)-2-HYDROXYPROPYL]CYCLOMALTOHEPTAOSE

Crystal structures of 6-O-[(R)-2-hydroxypropyl]- and 6-O-[(S)-2-hydrox ypropyl)-cyclomaltoheptaose were determined by X-ray analysis. In both structures, the 2-hydroxypropyl group is inserted into the macrocycli c cavity of the next molecule related by the two-fold screw axis, and a helically extended polymeric structure is formed by repetition of th e intermolecular inclusion. The hydroxyl group of the substituent grou p penetrates through the macrocyclic ring from the secondary hydroxyl side and is linked to an HO-6 group by a hydrogen bond. Comparison of intermolecular contacts of the substituent group indicates that the (S )-2-hydroxypropyl group is better fitted to the cavity than the (R)-2- hydroxypropyl group.