Thermodynamic characteristics of alanine-18-crown-6 ether complexes in binary water-acetone solvents

The formation of 18crown6 ether (18C6) complexes with D,Lalanine (Ala) in mixed water acetone solvents with 0.0, 0.08, 0.17, 0.22, and 0.30 mole fractions of acetone (T = 298.15 K) was investigated by means of calorimetry. Thermodynamic characteristics of the reaction of the molecular [Ala18C6] complex formation (?rG°, ?rH°, and T?rS°) were calculated on the basis of calorimetric data. Analysis of solvation contributions of reagents into the enthalpy of the [Ala18C6] formation reaction showed that the changes in the reaction energy when the solvent composition is varied are determined by the changes in the solvate state of 18C6.