Structure, molecular dynamics, and interactions in aqueous xylitol solutions

Area of Science:

• Physical Chemistry
• Solution Chemistry
• Dielectric Spectroscopy

Background:

• Understanding solute-solvent interactions is crucial in solution chemistry.
• Xylitol, a sugar alcohol, is widely used in food and pharmaceuticals.
• Dielectric spectroscopy is a powerful tool for probing molecular dynamics in liquids.

Purpose of the Study:

• To investigate the cooperative dynamics and hydration of aqueous xylitol solutions.
• To determine the hydration number of xylitol in water.
• To characterize the dynamics of water molecules and xylitol's hydroxyl groups.

Main Methods:

• Broad-band dielectric spectroscopy was employed.
• Experiments were conducted at 25 °C for xylitol concentrations up to 3.251 M.
• Spectral data were analyzed by assuming a superposition of five relaxation modes.

Main Results:

• An effective xylitol hydration number of 5.66 ± 0.08 was determined.
• Hydrating water molecules exhibit dynamics ~2.6 times slower than bulk water.
• Xylitol's hydroxyl groups contribute to relaxation, with central groups showing slower dynamics than distal ones.
• A relaxation at ~1.5 GHz suggests weak xylitol aggregation.

Conclusions:

• Xylitol significantly influences water dynamics in aqueous solutions.
• The study provides insights into the molecular interactions and structure of xylitol solutions.
• Dielectric spectroscopy effectively elucidates the complex dynamics in these systems.