Theoretical study of the formation of the α-cyclodextrin hexahydrate

The α-ciclodextrin (α-CD) consist of six glucopyranose units. The crystalline form I of α-CD is obtained in the solid state as the hexahydrate structure (α-CD · 6H2O) containing two water molecules inside and four outside the cavity. In this Letter, we report a quantum chemical study of the formation of the α-cyclodextrin hexahydrate using the semiempirical PM3 method and Density Functional Theory (BLYP/6-31G(d,p) calculation). Distinct chemical processes are considered for the calculation of the thermodynamic properties. We found a good agreement with experimental data for entropy, enthalpy and Gibbs free energy, which add support to the theoretical approach we used.