Molecular structures of glycal-based bolaamphiphiles: analysis of crystal packing and hydrogen-bond networks.
The crystal structures for the glycal bolaamphiphiles, 1,12-bis-(2,3-alpha-D-erythro-hex-2-enopyranosyloxy)-dodecane (1) and 1,12-bis-(2,3-alpha-D-threo-hex-2-enopyranosyloxy)-dodecane (2), were determined by single-crystal X-ray analysis. The structure for 1 showed that the alpha:alpha and alpha:beta diastereomers co-crystallized, with occupancy factors determining an isomeric ratio of 69:31. The pyranose rings for both structures are oriented away from each other and adopt a conventional glycal geometry. The head groups are nearly gauche to the hydrophobic chain, which adopts an all-trans zigzag conformation. Bolaamphiphile 1 packs in anti-parallel layers, while bolaamphiphile 2 displays a parallel arrangement of layers. Both structures display a three-dimensional hydrogen-bonding network involving the hydroxylic substituents on the head groups. The high similarity in large-scale solid state structures between 1 and glucosamide bolaamphiphile 3, and 2 and galactosamide bolaamphiphile 4 suggest a strong dependence on head group stereochemistry, and that only a few, key intermolecular interactions between head groups are necessary in controlling the ultimate structure observed. The solid state results may have implications for understanding the intermolecular forces directing nanoscale self-assembly in solution.
Tice
Nathan C
NC
Biomass Chemistry Laboratories, Forest Products Center, University of Tennessee, Knoxville, TN 37996-4570, United States.
Parkin
Sean
S
Bozell
Joseph J
JJ
D000473:Alkanes; D003460:Crystallization; D018360:Crystallography, X-Ray; D006027:Glycosides / Q000737:chemistry*; D006860:Hydrogen Bonding; D047028:Macrocyclic Compounds; D015394:Molecular Structure; D013501:Surface-Active Agents / Q000737:chemistry*
D000473:Alkanes; D006027:Glycosides; D047028:Macrocyclic Compounds; D013501:Surface-Active Agents; C007548:n-dodecane