title: Structure and stability of columnar cyclomaltohexaose (alpha-cyclodextrin) hydrate.
abstract: Rapid recrystallization of cyclomaltohexaose (alpha-cyclodextrin, alpha-CD) from aqueous solution resulted in formation of the columnar crystal structure of alpha-CD containing only water as the guest molecule. Complementary water vapor sorption and wide-angle X-ray diffractometry (WAXD) experiments were performed on the alpha-CD columnar structure to elucidate the crystal structure present at varying sorption levels. Equilibrium isothermal water vapor sorption experiments at 40 degrees C revealed that the alpha-CD columnar structure is unstable above a water activity of approximately 0.67. This was confirmed by WAXD diffractograms collected over time, which further revealed that alpha-CD columnar structure undergoes a phase transformation to the cage structure after approximately 0.25 h at 40 degrees C and a water activity of 1.0.
authors.affiliation: Fiber and Polymer Science Program, Campus Box 8301, North Carolina State University, Raleigh, NC 27695-8301, USA.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Hunt
authors.forename: Cristian C
authors.initials: CC
authors.lastname: Rusa
authors.forename: Alan E
authors.initials: AE
authors.lastname: Tonelli
authors.forename: C Maurice
authors.initials: CM
authors.lastname: Balik
mesh_terms: D002236:Carbohydrate Conformation; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D014867:Water / Q000737:chemistry; D047391:alpha-Cyclodextrins / Q000737:chemistry*
chemical_list: D047391:alpha-Cyclodextrins; D014867:Water