The dewetting transition and the hydrophobic effect.

Area of Science:

• Physical Chemistry
• Computational Biophysics
• Materials Science

Background:

• Understanding water behavior in confined hydrophobic environments is crucial for molecular interactions.
• Hydrophobic interactions play a key role in protein folding and self-assembly.

Purpose of the Study:

• To provide a molecular-level description of water behavior in hydrophobic spaces.
• To investigate the influence of solute size and solute-solvent interactions on water structure.
• To characterize the nature of hydrophobic interactions.

Main Methods:

• Molecular simulations of model solutes with varying surface areas.
• Analysis of solute-water interactions and water structural characteristics in the intersolute region.
• Identification of distinct water states: dry, oscillating, and wet.

Main Results:

• Three distinct water structures (dry, oscillating, wet) identified in hydrophobic spaces.
• A first-order-like phase transition observed between wet and dry states.
• Cavitation is not always preceded by a vapor layer around individual solutes.
• Density waves appear before a fully wet state is achieved.
• Microscopically wet states and interaction landscapes with traps/barriers are indicated for realistic interaction strengths.

Conclusions:

• Hydrophobic interactions are characterized by traps and barriers, not vacuum-induced collapse.
• The behavior of water in hydrophobic spaces is complex and depends on multiple factors.
• Current models of cavitation may need refinement for nanoscopic solutes.