title: A reevaluation of the epimeric and anomeric relationship of glucosides and galactosides in thermotropic liquid crystal self-assemblies.
abstract: Anomers and epimers α- and β-gluco and -galactosides are expected to behave differently. However, recent results on a series of Guerbet glycosides have indicated similar liquid crystal clearing temperatures for pure β-glucosides and the corresponding α-galactosides. This observation has led to speculation on similarities in the self-assembly interactions between the two systems, attributed to the trans-configuration of the 4-OH group and the hydrophobic aglycon. Previous simulations on related bilayers systems support this hypothesis, by relating this clearing transition temperature to intralayer (sugar-sugar) hydrogen bonding. In order to confirm the hypothesis, the comparison was expanded to include the cis-configurated pair, that is, α-gluco/β-galactoside. A set of α-configurated Guerbet glucosides as well as octyl α-galactoside were prepared and their thermotropic phase behavior studied. The data obtained enabled a complete comparison of the isomers of interest. While the results in general are in line with a pairing of the stereo-isomers according to the indicated cis/trans-configuration, differences within the pairs can be explained based on the direction of hydrogen bonds from a simple modeling study.
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia. rauzah@um.edu.my
authors.forename: Rauzah
authors.initials: R
authors.lastname: Hashim
authors.forename: Seyed M
authors.initials: SM
authors.lastname: Mirzadeh
authors.forename: Thorsten
authors.initials: T
authors.lastname: Heidelberg
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Minamikawa
authors.forename: Tanaka
authors.initials: T
authors.lastname: Yoshiaki
authors.forename: Akhiko
authors.initials: A
authors.lastname: Sugimura
mesh_terms: D002236:Carbohydrate Conformation; D003460:Crystallization; D005697:Galactosides / Q000138:chemical synthesis / Q000737:chemistry*; D005960:Glucosides / Q000138:chemical synthesis / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D008958:Models, Molecular; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D005697:Galactosides; D005960:Glucosides