THE CRYSTAL-STRUCTURE OF A 1-1 COMPLEX OF N-OCTYL ALPHA-D-GLUCOPYRANOSIDE AND BETA-D-GLUCOPYRANOSIDE AT 123-K

The 1:1 complex of n-octyl alpha- and beta-D-glucopyranoside, (C14H28O6)2, is triclinic, P1, with a = 5.021(1) [5.058(1)], b = 7.984(2) [7.996(3)], c = 20.848(3) [20.987(4)] angstrom, alpha = 79.06(2) [78.95(2)], beta = 81.99(1) [83.36(2)], gamma = 71.30(2) [72.57(2)], Z = 1, V = 774.47 [787.30] angstrom3 at 123 [293] K. The crystal structure is composed of ordered layers of each isomer, with hydrogen bonding across the alpha,beta bilayer and interdigitizing alkyl chains. The molecular packing is therefore the same as that observed in the crystal structures of other mesogenic n-alkyl O- or S-pyranosides, except for the presence of the two isomers. The molecules differ in the orientation of the primary alcohol groups, being g/g in the a isomer and g/t in the beta isomer. Otherwise the ring and alkyl chain conformations and dimensions are almost identical.