Hard fluid model for molecular solvation free energies

Abstract

Articles you may be interested inAffine-response model of molecular solvation of ions: Accurate predictions of asymmetric charging free energies J. Chem. Phys. 137, 124101 (2012); 10.1063/1.4752735Bounding the electrostatic free energies associated with linear continuum models of molecular solvation Different thermodynamic pathways to the solvation free energy of a spherical cavity in a hard sphere fluid The hard fluid model, which approximates packing forces in molecular liquids using hard sphere reference fluids, is applied to the prediction of excess solvation free energies of hard spheres and cavity size distributions in water, carbon tetrachloride, chloroform, n-hexane, n-dodecane, and n-undecyl alcohol. These are found to compare favorably with computer simulation measurements in these liquids, as well as experimental solubilities of rare gases in water, n-hexane, and n-dodecane (extrapolated to zero solute polarizability). The results are used to determine repulsive contributions to solvation free energies of atomic and molecular solutes in water and n-hexane. Attractive solvation free energies, determined from the difference between experimental and repulsive contributions, are found to correlate with solute polarizability, and are compared with dispersion energy estimates. The success of the hard fluid model in describing aqueous solvation suggests that the small size of water molecules, rather than their unique hydrogen bonding structure, plays an important role in hydrophobic hydration.

Understanding the role of hydrogen bonds in water dynamics and protein stability

“…On the other hand, a common opinion [27,28] is that the large free-energy change associated with the hydrophobic effect is due to the small size of the water molecules with respect to the solutes, and that the free-energy change associated with the network reorganization around hydrophobic particles is negligible due to compensation of enthalpy and entropy, although it may account for the large heat capacity change upon hydration. This observation apparently ruled out the Muller model, where the enthalpy-entropy compensation upon hydration was not present.…”

Pressure and temperature-dependent gauche-trans isomerization of 1-bromopropane: Raman measurement and statistical thermodynamic analysis

“…Note that the number density of 1-bromopropane in the liquid state is about 6 mole/nm 3 , and there are typically about 12 molecules in the first solvation shell around each molecule in a single component liquid. 9 Thus, roughly speaking, C a /2 represents the average molar cohesive energy contribution which each molecule in the first solvation shell makes to the overall isomerization free energy in the liquid state. The repulsive solvation free energy of each isomer is defined as the reversible work required to form a cavity sufficiently large to accommodate that isomer in a hard-body fluid representing the liquid of interest.…”

“…3,7,8 In particular, the perturbed hard-body fluid ͑PHF͒ formalism used in this work treats the solution of interest as a repulsive reference fluid with a van der Waals mean field of attractive intermolecular interactions. This approach, which has previously been applied to a variety of molecular solvation, reaction and vibration processes, [7][8][9][10][11][12][13][14][15] is here used to interpret temperature-and pressure-dependent changes in the gauche-trans isomer population ratio in liquid 1-bromopropane ͑see Fig. 1͒, by comparing theoretical predictions with Raman spectroscopic measurements.…”

Solubility of freons in polar and non-polar liquids at 298.15 K

“…Pierotti [22,23] assumed equivalency of partial molar free energy of cavity formation and cavity formation energy (CFE). The cavity formation energy is a substantial part of the total solvation energy for most of the fluid and very important to determine the solubility [26,27]. Pierotti [23] calculated the reversible work required ½Wðr; pÞ to produced cavity in the fluid based on scaled particle theory of Reiss et al [19,20] and compared the same required for macroscopic cavity formation in classical thermodynamics, then he calculated partial molar free energy of cavity formation.…”