Double Hydrogen Bonding Dimerization Propensity of Aqueous Hydroxy Acids Investigated Using Vibrational Optical...

Area of Science:

• Biochemistry and Spectroscopy
• Molecular Dynamics and Chemical Physics

Background:

• Lactic and malic acids are vital in biological systems and industry.
• Understanding their behavior in aqueous solutions is crucial for various applications.
• Vibrational spectroscopy offers sensitive analysis of molecular structure and interactions.

Purpose of the Study:

• To investigate the conformational behavior and dimerization of l-lactic and l-malic acids in water.
• To assess the propensity for double hydrogen bonding and dimer formation.
• To explore the influence of pH, temperature, and concentration on their molecular dynamics.

Main Methods:

• Utilized Raman spectroscopy and Raman optical activity (ROA) for experimental analysis.
• Performed extensive theoretical calculations for vibrational properties.
• Employed molecular dynamics simulations to model conformational behavior in water.
• Conducted complementary experiments including IR absorption, vibrational circular dichroism, and NMR.

Main Results:

• Estimated low incidence of hydrogen-bonded dimers for lactic acid in water.
• Found dimer concentration comparable to monomers for malic acid in aqueous solutions.
• Validated experimental findings by comparing calculated spectral features of conformers with experimental data.

Conclusions:

• The study highlights the importance of a hybrid approach combining experimental and theoretical methods.
• Relying solely on experimental spectra can be insufficient for accurately studying dimer formation.
• Provides a detailed understanding of lactic and malic acid molecular dynamics in aqueous environments.