Work

Solvation thermodynamics revisited

Year: 2026

Type: article

Abstract: Most chemical and biochemical reactions occur in solution; however, many details of the thermodynamics of solvation are not well understood, especially with regard to the role of energy and entropy in the solvation process. Currently, a prevailing view in the field is that the solvation free energy is fully determined by solute-solvent interactions acting through both energetic and entropic contributions. This rests on the claim, presented by Yu and Karplus [J. Chem. Phys. 89, 2366 (1988)], that the solvent-solvent energetic and entropic contributions to the solvation free energy exactly cancel. Here, we show that this result is not correct but rather arises from an erroneous assignment of the solvent-solvent and solute-solvent entropic contributions. Namely, we demonstrate that the solvent-solvent and solute-solvent energetic contributions to the free energy, which have an unambiguous assignment, are not compatible with the Yu-Karplus decomposition of the solvation entropy. This indicates that, contrary to a now commonly held view, rearrangements of the solvent upon introduction of a solute may contribute both energetically and entropically to the solvation free energy.

Source: The Journal of Chemical Physics

DOI: 10.1063/5.0346490

Authors: Ward H. Thompson, Gregory K. Schenter, Christopher J. Mundy, Brian B. Laird

Institutions: University of Kansas, Pacific Northwest National Laboratory, University of Washington

Language: English

Topic: Advanced Physical and Chemical Molecular Interactions

Subfield: Physical and Theoretical Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, U.S. Department of Energy

Awards: G4064337900, Direct Calculation of Activation Energies and Entropies for Chemical Dynamics