Calculation of mobility and entropy of the binding of molecules by crystals

Abstract

A simple method for evaluating a range of molecular movements in crystals has been developed. This estimate is needed to calculate the entropy of binding, in particular in protein–ligand complexes. The estimate is based on experimental data concerning the enthalpy of sublimation and saturated vapor pressure obtained for 15 organic crystals with melting temperatures of 25–80°С. For this set, we calculated the values of the average range and the corresponding average amplitude of molecular movements in crystals that constituted 0.75 ± 0.14 Å and 0.18 ± 0.03 Å, respectively. The entropy of sublimation calculated based on the average range of molecular movements in crystals was well consistent with the experimental data.