Effect of cluster formation of solvent molecules on the preferential solvatation of anthracene in binary alcoholic solutions

The formation of the solvatation shell of anthracene molecule was investigated in binary mixtures of protic alcoholic solvents by solvent-relaxation measurements, anisotropy decay studies and quantum-chemical modeling. Results show significant change of the solvatation shell of anthracene dissolved in binary solutions of methanol, ethanol or n-propanol with n-butanol when the molar fraction of n-butanol in the bulk solution exceeds a critical value. Both the solvent relaxation and anisotropy decay data suggest clusterization process in the solvatation shell of the anthracene probe. Quantum chemical calculation supports formation of energetically preferred heteromolecular (X2(BuOH)2, X = MeOH, EtOH or PrOH) clusters around the solute.