Determination of the dimerization constant of pinacyanol dye in mixed aqueous-organic solvent media with different hydrophobic character

► Aggregation behavior of PC dye in aqueous-organic solvent mixed media. ► Presence of monomer-dimer equilibrium in all mixed media containing 5% organic solvent. ► Determination of dimerization constant KD of the dye in mixed media. ► Increase in the hydrophobic character of the mixed media favors dye aggregates. ► Importance of hydrophobic interactions in the aggregation of dyes besides the dielectric constant of the media.