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Hydrogen Bonding Interactions between a Representative Pyridinium-Based Ionic Liquid [BuPy][BF 4 ] and Water/Dimethyl Sulfoxide

2010; American Chemical Society; Volume: 114; Issue: 26 Linguagem: Inglês

10.1021/jp103438q

1520-6106

Nannan Wang, Qingguo Zhang, Fu‐Gen Wu, Qingzhong Li, Zhi‐Wu Yu,

Chemical and Physical Properties in Aqueous Solutions

Infrared spectroscopy and density functional theory calculations have been applied to elucidate the hydrogen bonding interactions between water/dimethyl sulfoxide (DMSO) and a representative pyridinium-based ionic liquid, 1-butylpyridinium tetrafluoroborate ([BuPy][BF(4)]). It has been found that both solvents can interact with the BuPy(+) cation through the aromatic C-H. The strength of the H-bonds involving the aromatic C-H in water is similar to that in pure [BuPy][BF(4)], but is much stronger in DMSO. For DMSO, when it forms H-bonds with the BuPy(+) cation through its S=O group, its back-side methyl groups act as electron donors, while the butyl group of the cation acts as an electron acceptor. For water, when it forms the strong anion-HOH-anion complex, it can also form H-bonds with the aromatic C-H on the BuPy(+) cation. This is different from the imidazolium-based ionic liquid, where the strong anion-cation interaction and steric hindrance from the alkyls prevent water molecules from H-bonding with the aromatic C-H other than with the anion.