title: Diffusion of a highly charged supramolecular assembly: direct observation of ion association in water.
abstract: The diffusion coefficient of the self-assembled supramolecular cluster [Ga4L6]12- depends on the cationic counterions in solution. Diffusion coefficients were determined using the pulsed-gradient spin-echo 1H NMR method and fit using nonlinear least-squares refinement. Saturation studies revealed a small number of ion-association sites on the exterior of the assembly and the direct observation of ion association in water. The addition of excess alkali-metal cations displaces the ion-associated hydrophobic tetra-alkyl-ammonium cations. Comparisons between tetraethyl- and tetra-propyl-ammonium show a preference for ion association with the more hydrophobic cation.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Pluth
authors.forename: Bryan E F
authors.initials: BE
authors.lastname: Tiedemann
authors.forename: Herman
authors.initials: H
authors.lastname: van Halbeek
authors.forename: Rudi
authors.initials: R
authors.lastname: Nunlist
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Raymond