Investigating the H‑Bond Network of Pyridine-Water Aqueous Solutions by Raman Spectroscopy and DFT.

Area of Science:

• Physical Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Understanding hydrogen bonding in binary solutions is crucial for various chemical applications.
• Pyridine-water mixtures are model systems for studying interactions in N-heterocyclic solutions.

Purpose of the Study:

• To investigate the effects of pyridine concentration on hydrogen bonding in pyridine-water solutions.
• To elucidate the relationship between intermolecular hydrogen bonds and vibrational spectra.

Main Methods:

• Utilized spontaneous Raman spectroscopy and stimulated Raman scattering.
• Employed Density Functional Theory (DFT) for computational analysis.
• Analyzed spectral shifts and vibrational coupling.

Main Results:

• Observed irregular blue shifts in water's O-H stretching and nonbond vibrations with increasing pyridine mole fraction.
• Noted shifts towards higher wavenumbers for pyridine's ring breathing, triangle, and C-H stretching modes upon dilution.
• Confirmed DFT simulations align well with experimental Raman spectroscopy findings.

Conclusions:

• Intermolecular hydrogen bond variations significantly influence the Raman spectra of pyridine-water solutions.
• Vibrational coupling between different chemical bonds plays a role in spectral changes.
• The study provides a valuable reference for analyzing hydrogen bond networks in N-heterocyclic binary systems.