Molecular and crystal structures of two 1,6-anhydro-β-maltotriose derivatives

Abstract

Crystal structures of two 1,6-anhydro-β-maltotriose derivatives, 1,6-anhydro-β-maltotriose nonaacetate and 6″-bromo-6″-deoxy-1,6-anhydro-β-maltotriose octaacetate, have been determined. Both structures are isomorphous and belong to the orthorhombic system, space group of P2 12 12 1, with cell dimensions of a = 15.659(3) A ̊ , b = 20.587(6) A ̊ , c = 13.023(2) A ̊ and a = 15.402(7) A ̊ , b = 19.737(8) A ̊ , c = 13.481(5) A ̊ , respectively. Each molecule has three α-(1 → 4)-linked glucose units, and two of them have a typical 4 C 1 chair conformation, while the glucose unit with the 1,6-anhydro bridge has a 1 C 4 chair-envelope intermediate conformation. In spite of introducing the 1,6-anhydro bridge and acetyl groups, the conformations of the glycosidic linkages in these molecules are almost the same as those of other α-(1 → 4)-linked oligosaccharides. Crystal structures are stabilized by hydrophobic interactions and by a weak intermolecular hydrogen bond of C-H ··· O.