THE THERMODYNAMICS OF THE BINDING OF BENZENE TO BETA-CYCLODEXTRIN IN AQUEOUS-SOLUTION

The apparent enthalpies, entropies and Gibbs energies for the binding of benzene to beta-cyclodextrin in aqueous solution have been determined at 291.15, 298.15 and 308.15 K by microcalorimetry. The calorimetric data are consistent with a binding model that assumes formation of both 1:1 and 2:1 (benzene:beta-cyclodextrin) adducts. The apparent change in heat capacity for the 1:1 binding, calculated from the temperature derivative of the enthalpy changes, indicates that the hydrophobic effect is the driving force for formation and stability of this complex.