WATER-SURFACTANT CONTACT STUDIED BY F-19-H-1 HETERONUCLEAR OVERHAUSEREFFECT SPECTROSCOPY

Intermolecular F-19-H-1 cross-relaxation is measured using heteronucle ar Overhauser effect MMR spectroscopy (HOESY) in the micellar solution of cesium pentadecafluorooctanoate. The results are analyzed in terms of a weak H-1-F-19 cross-relaxation between the water protons and the fluorines in the fluoroalkyl chain and a strong F-19-F-19 cross-relax ation within the fluoroalkyl chain. The water-surfactant cross-relaxat ion indicates a water approach to the first CF2 segment in the order o f 2.0 Angstrom and a short (much less than ns) water residence time. E vidence of fluorine hydration further inside the micelle is presented. (C) 1998 Academic Press.