Thermodynamic and Structural Evidence for Reduced Hydrogen Bonding among Water Molecules near Small Hydrophobic Solutes.

摘要: The structure of water molecules near a hydrophobic solute remains elusive despite long history scrutiny. Here, we re-examine the subtle issue by combination thermodynamic analysis for Henry's constants several nonpolar gases over broad range temperatures and molecular dynamic simulations in hydration shell using popular semiempirical models liquid water. Both structural data indicate that reduces degree hydrogen bonding among molecules, effect becomes more prominent at high temperatures. Hydrogen-bond formation is slightly hindered due to restriction freedom solvation shell, confinement significant as temperature increases. Reduction extent fully consistent with positive contribution small solution heat capacity. As predicted scaled-particle theory, both simulation results suggest entropy determined primarily cavity water, its magnitude rising size but declining temperature.