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10:28
Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy
Published on: May 27, 2018
Water structural transformation at molecular hydrophobic interfaces.
Joel G Davis1, Kamil P Gierszal, Ping Wang
1Purdue University, Department of Chemistry, West Lafayette, Indiana 47907, USA.
Nature
|November 23, 2012
Summary
Hydrophobic hydration
Area of Science:
- Water-solute interactions
- Biophysical chemistry
- Chemical physics
Background:
- Hydrophobic hydration is crucial for biological processes like protein folding.
- Historically, hydration shells were modeled as clathrate hydrates.
- Recent studies highlight the significance of length scales in hydrophobic hydration.
Purpose of the Study:
- To investigate the structural and dynamic properties of hydrophobic hydration shells.
- To explore the influence of temperature and chain length on water structure around hydrophobic solutes.
- To map vibrational spectroscopic features of hydration shells using Raman scattering.
Main Methods:
- Combined polarized, isotopic, and temperature-dependent Raman scattering.
- Multivariate curve resolution (Raman-MCR) analysis.
- Study of linear alcohols from methanol to heptanol across 0-100 °C.
Main Results:
- At low temperatures, hydration shells exhibit enhanced tetrahedral water order and fewer weak hydrogen bonds compared to bulk water.
- This ordered structure diminishes with increasing temperature.
- For hydrophobic chains longer than ~1 nm, a more disordered structure with weaker hydrogen bonds emerges at higher temperatures.
Conclusions:
- The findings support the concept of a thermally induced water structural transformation in hydrophobic hydration.
- Observations are consistent with the predicted hydrophobic crossover phenomenon at specific length scales (~1 nm).
- This study provides detailed insights into the temperature-dependent behavior of water structure around hydrophobic molecules.
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