Diffusion of a highly charged supramolecular assembly: direct observation of ion association in water.
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.
Pluth
Michael D
MD
Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Tiedemann
Bryan E F
BE
van Halbeek
Herman
H
Nunlist
Rudi
R
Raymond
Kenneth N
KN