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Condensation of Co ++ ions on chondroitin sulfate from transport coefficients and proton NMR measurements in aqueous solutions
Author(s) -
Tivant P.,
Turq P.,
Chemla M.,
Magdelenat H.,
Spegt P.,
Weill G.
Publication year - 1979
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1979.360180803
Subject(s) - counterion , chemistry , counterion condensation , aqueous solution , ion , polyelectrolyte , proton , diffusion , inorganic chemistry , analytical chemistry (journal) , chemical physics , polymer , thermodynamics , organic chemistry , physics , quantum mechanics
The “condensed” counterions which characterize high‐charge‐density polyelectrolyte solutions can be analyzed into two subpopulations: (1) site‐bound counterions and (2) atmospherically entrapped counterions. The distinction is achieved experimentally by combining the data from self‐diffusion coefficient or electrical mobility measurements, which give the amount of “condensed” ions, and those from nmr, chemical shift measurements, which indicate the amount of site‐bound ions. In the case of a solution of chondroitin sulfate with excess Co ++ counterions, it can be estimated that 20% of the structural charge of the polyion is neutralized by site‐bound, dehydrated, condensed counterions, while a further 30% is neutralized by atmospherically entrapped, hydrated counterions.