Hydrogen bonding interactions between a representative pyridinium-based ionic liquid [BuPy][BF4] and water/dimethyl...

Area of Science:

• Physical Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Ionic liquids (ILs) are tunable solvents with unique properties.
• Understanding solvent-IL interactions is crucial for designing new materials.
• Pyridinium-based ILs show promise in various applications.

Purpose of the Study:

• To investigate hydrogen bonding between water/DMSO and 1-butylpyridinium tetrafluoroborate ([BuPy][BF(4)]).
• To elucidate the role of aromatic C-H in IL-solvent interactions.
• To compare interactions in pyridinium-based ILs with imidazolium-based ILs.

Main Methods:

• Infrared (IR) spectroscopy was employed to study hydrogen bonding.
• Density Functional Theory (DFT) calculations were used to model interactions.
• Analysis focused on cation-solvent and anion-solvent interactions.

Main Results:

• Both water and DMSO interact with the [BuPy][BF(4)] cation via its aromatic C-H bonds.
• Hydrogen bond strength with the aromatic C-H is greater in DMSO than in water.
• DMSO forms H-bonds through its S=O group, with methyl groups acting as donors.
• Water forms anion-HOH-anion complexes and also H-bonds with the cation's aromatic C-H.
• Unlike imidazolium ILs, pyridinium ILs allow water to interact with the aromatic C-H.

Conclusions:

• Pyridinium cations exhibit distinct hydrogen bonding patterns with water and DMSO compared to imidazolium cations.
• The aromatic C-H in [BuPy][BF(4)] plays a significant role in solvent interactions.
• These findings offer insights into the solvation behavior of ionic liquids.