Structural and spectroscopic properties of water around small hydrophobic solutes

J Phys Chem B. 2012 Sep 27;116(38):11695-700. doi: 10.1021/jp303213m. Epub 2012 Sep 18.

Abstract

We investigated the structural, dynamical and spectroscopic properties of water molecules around a solvated methane by means of Car-Parrinello molecular dynamics simulations. Despite their mobility, in the first shell, water molecules are dynamically displaced in a clathrate-like cage around the hydrophobic solute. No significant differences in water geometrical parameters, in molecular dipole moments or in hydrogen bonding properties, are observed between in-shell and out-shell molecules, indicating that liquid water can accommodate a small hydrophobic solute without altering its structural properties. The calculated contribution of the first-shell water molecules to the infrared spectra does not show significant differences with respect the bulk signal once the effects of the missing polarization of second-shell molecules has been taken into account. Small fingerprints of the clathrate-like structure appear in the vibrational density of states in the libration and OH stretching regions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Hydrogen Bonding
  • Hydrophobic and Hydrophilic Interactions
  • Methane / chemistry*
  • Models, Molecular
  • Molecular Dynamics Simulation*
  • Molecular Structure
  • Spectrophotometry, Infrared
  • Water / chemistry*

Substances

  • Water
  • Methane