DIVALENT PARAMAGNETIC COUNTERIONS SITE BINDING IN POLYELECTROLYTE SOLUTIONS - ANALYSIS OF THE FREQUENCY-DEPENDENCE OF THE WATER PROTONS MAGNETIC-RELAXATION AND THE CHARACTERISTIC PARAMETERS OF SITE BINDING

Chemical shift and relaxation time measurements on the water protons in polyelectrolyte solutions containing divalent paramagnetic counterions have shown the existence of three types of counterions: - site bound with loss of water molecules and partial or complete release of the electrostriction in the first hydration sphere, - atmospherically trapped with no change in hydration, - free. The overall stoichiometry of the two former is in agreement with Manning's fraction of condensed counterions. A complete analysis of the frequency dependent contribution of site bound counterions to the water protons relaxation times leads us to interesting conclusions on the modifications of the first hydration shell and on the life time of site binding. © 1979.