CRYSTAL-STRUCTURES OF METHYL 6-O-N-ALKANOYL-BETA-D-GLUCOPYRANOSIDES

The crystal structures of methyl 6-O-n-octanoyl-beta-D-glucopyranoside 1 and methyl 6-O-n-decanoyl-beta-D-glucopyranoside 2, which are types of glycosurfactants, were determined by X-ray analysis. Anhydrous crystals were obtained from a diethyl ether-acetone solution. The crystals are monoclinic, and the space group is P2(1) with Z = 2. The cell dimensions are as follows: 1, a = 7.760(1), b = 7.373(1), c = 15.514(1)Angstrom, beta = 102.91(1)degrees; 2, a = 7.724(1), b = 7.351(1), c = 16.957(2)Angstrom, beta = 94.81(1)degrees. The glucopyranoside moieties are in a C-4(1) chair conformation and the conformation of the alkyl chain is the all-trans type. The molecules are arranged parallel to the a-e plane in a bilayer structure where alkyl chains are interdigitated. The sugar moieties are stacked to form a hydrophilic zone elongated parallel to the ab plane and arranged with a packing structure similar to that of methyl beta-D-glucopyranoside in spite of a substituted long alkyl chain. Hydrogen bondings of sugar moieties are found only between the bilayers.