title: Switching from altro-alpha-cyclodextrin dimer to pseudo[1]rotaxane dimer through tumbling.
abstract: An alkyl altro-alpha-CD dimer was converted to the pseudo[1]rotaxane dimer through tumbling of the altropyranose unit of altro-alpha-CD in D(2)O. The tumbling of the altropyranose unit was found to be a rotational vibration with 1.18 x 10(-3) s(-1) at 293 K. The activation free energy (DeltaG(double dagger)(288K)) for the conformational change from an alkyl altro-alpha-CD dimer to pseudo[1]rotaxane dimer was 88.0 kJ mol(-1), which corresponds to the breakage of the hydrogen bond network for the tumbling of an altropyranose unit.
authors.affiliation: Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Atsuhisa
authors.initials: A
authors.lastname: Miyawaki
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takashima
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Akira
authors.initials: A
authors.lastname: Harada
mesh_terms: D019281:Dimerization; D015394:Molecular Structure; D043862:Rotaxanes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D047391:alpha-Cyclodextrins / Q000737:chemistry*
chemical_list: D043862:Rotaxanes; D047391:alpha-Cyclodextrins; C032613:alpha-cyclodextrin