Studies on solvation interaction: Solubility of a betaine dye and a ketocyanine dye in homogeneous and heterogeneous media

Abstract

Solubility of 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl) phenolate, commonly known as Reichardt's betaine dye and a ketocyanine dye has been determined in binary solvent mixtures and in cationic and anionic micellar media. In all the binary mixtures the standard molar free energy of solution, as given by <i>log s</i>₁₂<i> </i>where <i>s</i>₁₂ is the solubility in the binary mixture, cannot be represented by the average of <i>log s </i>values in pure solvents weighted with respect to mole fraction of the components. The deviation from the mole fraction average value, as given by Δ (<i>log s</i>)<i>=log s</i>₁₂<i>-</i>(<i>x</i>₁<i>log s</i>₁<i>+ x</i>₂<i>log s</i>₂)<i>, </i>has been calculated and compared with the similar parameter as obtained from the electronic spectroscopic transition energy. The results have been explained in terms of solute-solvent and solvent-solvent interaction. Study in micellar media provides information regarding the location of the dye in the heterogeneous media.