On Enthalpy–Entropy Compensation Characterizing Processes in Aqueous Solution

The phenomenon of enthalpy–entropy compensation emerges as a ubiquitous feature of processes occurring in water, especially those involving biological macromolecules. In writing the present study, the aim was not to review most of the rationalizations proposed so far but to focus on a general theory of hydration, partly developed and applied by one of us. This theory poses a physical condition for the occurrence of enthalpy–entropy compensation: the energetic strength of the solute–water attraction must be weak compared to that of water–water H-bonds. This condition is largely fulfilled in water due to the cooperativity of its three-dimensional H-bonded network.