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Thermodynamic hydration shell behavior of glycine
Francesco D'Amico1, Filippo Bencivenga, Gaia Camisasca
1Elettra-Sincrotrone Trieste, Area Science Park, I-34149 Trieste, Italy. francesco.damico@elettra.trieste.it
The Journal of Chemical Physics
|July 5, 2013
Summary
This study investigated glycine aqueous solutions using UV Brillouin and Raman spectroscopy. Results show hydrogen bond strength between water molecules hydrating hydrophobic groups increases at low temperatures.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Solution Chemistry
Background:
- Understanding the behavior of amino acids in aqueous solutions is crucial for biological and chemical processes.
- Hydrogen bonding (HBs) plays a significant role in the structure and dynamics of these solutions.
- Glycine, the simplest amino acid, serves as a model compound for studying hydration effects.
Purpose of the Study:
- To investigate the temperature and concentration dependence of glycine aqueous solutions.
- To elucidate the role of hydrogen bonds (HBs) in the hydration of glycine's hydrophobic groups.
- To compare relaxation dynamics derived from Brillouin spectroscopy with vibrational dephasing lifetimes from Raman spectroscopy.
Main Methods:
- Utilized UV Brillouin and Raman spectroscopy to analyze glycine aqueous solutions.
- Determined average relaxation time (τ) from Brillouin spectra, reflecting HB dynamics.
- Analyzed Raman spectra lineshapes to derive vibrational dephasing lifetimes of atoms involved in HBs.
Main Results:
- Brillouin spectra revealed relaxation times (τ) related to hydrogen bond (HB) formation and breaking mechanisms.
- Comparison of τ with Raman-derived lifetimes allowed tracing thermodynamic behavior of specific HBs.
- Confirmed the significant role of water molecules surrounding hydrophobic groups in glycine hydration.
Conclusions:
- At low temperatures, the hydrogen bond strength between water molecules hydrating glycine's hydrophobic groups is greater than in bulk water or between glycine and water.
- Raman spectroscopy data can be used to track the thermodynamic behavior of specific hydrogen bonds.
- The findings highlight the unique hydration properties of glycine in aqueous solutions.
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