Nuclear magnetic resonance studies of aqueous and related systems.

In recent years magnetic resonance methods have been used to shed fresh light on the problems associated with ionic solvation and interactions between ions in solution. This thesis concerns the application of the Nuclear Magnetic Resonance solvent shift technique to both aqueous and non-aqueous electrolyte solutions. Two methods of determining a set of self consistent 'absolute' ion shifts for aqueous solutions are described, and an attempt is made to establish how such shifts vary with changes in solution temperature. The resulting shifts for simple ions are discussed in terms of a model that considers the competitive nature of hydrogen bonding to the pure water and bonding between the water and the ion. The shifts of the quaternary ammonium and related ions are discussed in terms of a model based on enclathration of the solute. For these latter ions a possible explanation for anomalous n.m.r. salt shifts, previously reported by Hertz and Spalthoff, is given. Salt and ion shifts measured in the related solvents, methanol, ethanol and ethylene diol are compared and contrasted with the aqueous results. Evidence for solvent-shared ion-pairs in methanolic solution is given. A report of a preliminary investigation concerning the determination of absolute ion shifts for solutions of electrolytes in liquid ammonia is given. Problems connected with n.m.r. salt shift referencing, that are inherently associated with investigations of type undertaken, are discussed. The use of a suitably chosen internal reference is suggested. In this context, the use of the proton resonances of a quaternary ammonium cation such as (CH3)4N+has proved to be satisfactory for the aqueous solutions.