Solid-state structure of methyl 2,4,6-tri-O-acetyl-3-O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-β-D-galactopyranoside and methyl 3,4,6-tri-O-acetyl-2-O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-β-D-galactopyranoside

Comprehensive structural analyses of methyl 2,4,6-tri-O-acetyl-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-beta-D-galactopyranoside (1) and methyl 3,4,6-tri-O-acetyl-2-O-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-B-D-galactopyranoside (2) have been performed. The analyses combined experimental and theoretical methods: single-crystal and powder X-ray diffraction and C-13 CP/MAS NMR spectroscopy served as experimental techniques, whereas the grid search of the conformers of disaccharides implemented by genetic algorithm was chosen as the theoretical method. One of the calculated conformers of 1 fits the experimental structure very well. Although the two best conformations of 2 are of similar energy, their structures are significantly different. Probably therefore 2 cannot form any crystallographic forms and is amorphous. (C) 2012 Elsevier B.V. All rights reserved.