Cs-133 NMR spectroscopic investigation of the interaction of Cs-133(+) with monovalent cations in aqueous solution

Cs-133 NMR spectroscopy was used to study the interaction of Cs-133(+) Wi t h monovalent cations in aqueous solution. The interaction between Cs-133(+) and the cations causes a repulsive polarization in the electron environmen t of Cs-133(+), which is detected by a change in its resonance frequency. T he resulting Cs-133 chemical shift seemed to be dependent on the activities and the single-ion enthalpies and entropies of hydration of the cations. T he hydration cospheres of an ion are the barriers through which Cs-133(+). Must pass in order to come into contact with the cation. These hydration co sphere barriers can be related to the single-ion enthalpy and entropy of hy dration of the cation. The experiments revealed that Cs-133(+) is not nearl y as sensitive a probe as Xe-129, presumably due to its more tightly bound hydration cospheres. However, Cs-133 NMR was moderately successful in predi cting trends in the chemical shift behavior induced by the cations studied.