Preferential Solvation Studied by the Fluorescence Spectrum of Pyrene in Water-Alcohol Binary Mixtures

The local mole fraction of an alcohol such as methanol, ethanol, and 1-propanol was determined on the basis of the polarity variation sensed by pyrene in water-alcohol binary mixtures. The data indicate that alcohol molecules preferentially solvate pyrene in water; the degree of preferential solvation increases with an increase in the extent of the hydrophobic interaction between pyrene and alcohols.