title: pH dependent in-out isomerism of an amino-beta-cyclodextrin derivative.
abstract: An amino derivative of beta-cyclodextrin [6-(6-aminehexanamide)-6-deoxy)-beta-cyclodextrin (6-betaCD)] was synthesized, and the formation of an intramolecular inclusion complex was studied by NMR techniques. The deprotonation/protonation of the amino group stimulates an in/out movement of the pendant group toward/from the cyclodextrin cavity, the protonated species lying outside the hydrophobic cyclodextrin cavity but the unprotonated one residing inside and outside the cavity. The protonation of the amino group is a fast exchange rate NMR time-scale process, but the chain movement is a slow one. The equilibrium constants of both processes were determined from 1H NMR experiments and the kinetic constants for the slow process were determined from exchange spectroscopy (EXSY) experiments.
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain.
authors.forename: Mercedes Alvarez
authors.initials: MA
authors.lastname: Alcalde
authors.forename: Cristina
authors.initials: C
authors.lastname: Gancedo
authors.forename: Aida
authors.initials: A
authors.lastname: Jover
authors.forename: Jorge
authors.initials: J
authors.lastname: Carrazana
authors.forename: Victor H
authors.initials: VH
authors.lastname: Soto
authors.forename: Francisco
authors.initials: F
authors.lastname: Meijide
authors.forename: José Vazquez
authors.initials: JV
authors.lastname: Tato