title: Hydrogen bonding interactions between a representative pyridinium-based ionic liquid [BuPy][BF4] and water/dimethyl sulfoxide.
abstract: 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.
authors.affiliation: Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Nan-Nan
authors.initials: NN
authors.lastname: Wang
authors.forename: Qing-Guo
authors.initials: QG
authors.lastname: Zhang
authors.forename: Fu-Gen
authors.initials: FG
authors.lastname: Wu
authors.forename: Qing-Zhong
authors.initials: QZ
authors.lastname: Li
authors.forename: Zhi-Wu
authors.initials: ZW
authors.lastname: Yu
mesh_terms: D001881:Borates / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011726:Pyridinium Compounds / Q000737:chemistry*; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D001881:Borates; D007093:Imidazoles; D052578:Ionic Liquids; D011726:Pyridinium Compounds; D014867:Water; C518932:n-butylpyridinium tetrafluoroborate; D004121:Dimethyl Sulfoxide