Solute-Solvent Contact by Intermolecular Cross Relaxation : I. The Nature of the Water-Hydrophobic Interface

• Intermolecular cross-relaxation rates between solute and solvent were measured by {H-1} F-19 nuclear magnetic resonance experiments in aqueous molecular solutions of ammonium perfluoro-octanoate and sodium trifluoroacetate. The experiments performed at three different magnetic fields provide frequency-dependent cross-relaxation rates which demonstrate clearly the lack of extreme narrowing for nuclear spin relaxation by diffusionally modulated intermolecular interactions. Supplemented by suitable intramolecular cross-relaxation, longitudinal relaxation, and self-diffusion data, the obtained cross-relaxation rates are evaluated within the framework of recent relaxation models and provide information about the hydrophobic hydration. In particular, water dynamics around the trifluoromethyl group in ammonium perfluoro-octanoate are more retarded than that in the smaller trifluoroacetate

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

Nyckelord

molecular-dynamics simulation

overhauser effect measurements

nuclear-spin relaxation

pair correlation-functions

low ionic-strength

nmr relaxation

magnetic-resonance

carboxylic-acids

translational diffusion

electronic relaxation

Physical chemistry

Fysikalisk kemi

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