SPECTROCHEMICAL INVESTIGATIONS OF PREFERENTIAL SOLVATION - FLUORESCENCE EMISSION BEHAVIOR OF SELECT POLYCYCLIC AROMATIC HYDROCARBON SOLUTE PROBES DISSOLVED IN MIXED-SOLVENTS

A spectrofluorometric method is developed to examine preferential solv ation of a probe molecule dissolved in binary solvent mixtures. The me thod assumes that the solvational sphere around every fluorophore is s olvated by only one type of solvent component and that each solvated f luorophore contributes to the measured emission intensity. Expressions derived from the model are illustrated using observed fluorescence em ission behavior of pyrene, benzo[e]pyrene, benzo[ghi]perylene, and cor onene dissolved in binary n-heptane + 1,4-dioxane, n-heptane + tetrahy drofuran, methanol + acetonitrile, and dibutyl ether + acetonitrile so lvent mixtures, which were measured as part of the present study. Also discussed are deficiencies inherent in several of the spectrofluorome tric probe methods published in the chemical literature.