The proposed research involves the development of a novel competitive association method for determining association constants for very weak molecular complexes from measured solute solubility and chromatographic partition coefficients in binary solvent mixtures. Research efforts will be focused in five areas. First, a systematic study will be made of the solubility and spectroscopic properties of carbazole, phenoxazine and phenothiazine dissolved in a large number of binary solvent mixtures. Second, the competitive association model will be extended to include ternary solvent systems in order to assess the effect that a third inert cosolvent has on the calculated association parameters. Third, gas-liquid chromatographic methods and partition coefficients will be used to test the applications and limitations of the derived competitive association model. Fourth, the basic thermodynamic mixing model will be extended to excess volumes of ternary associated nonelectrolyte solutions. Finally, the basic thermodynamic model will be extended to tautomeric solute molecules.
