Ultrasonic and DFT study of intermolecular association through hydrogen bonding in aqueous solutions of glycerol

The experimental measurements of density, viscosity and ultrasonic velocity of aqueous glycerol solutions were carried out as functions of concentration (0.1 <= m [mol kg(-1)]<= 1.0) and temperature (303.15 <= T [K]<= 323.15). The isentropic compressibility (beta(s)), acoustic impedance (Z), hydration number (H-n), intermolecular free length (L-f), classical sound absorption (alpha/f(2))(class) and shear relaxation time (tau) were calculated by using the measured data. These parameters have been interpreted in terms of solute-solvent interactions. The quantum chemical calculations were performed to study the hydrogen bonding in interacting complex formed between glycerol and water molecules. Computations have been done by using Density Functional Theory (DFT) method at B3LYP/6-31 + g(d) level of theory to study the equilibrium structure of glycerol, glycerol-water interacting complex and vibrational frequencies. The solution phase study was carried out using Onsager's reaction field model in water solvent. The computed vibrational frequencies are in good agreement with the main features of the experimental spectrum when four water molecules are considered explicitly with glycerol. The interaction energy (E-total), hydrogen bond lengths and dipole moment (mu(m)) of the interacting complex are also presented and discussed with in the light of solute-solvent interactions. (C) 2008 Elsevier B.V. All rights reserved.