Anomalous conformational change in 1-butyl-3-methylimidazolium tetrafluoroborate-D2O mixtures.
We have investigated the effect of deuterated water on the conformational equilibrium between the gauche and trans conformers of the [bmim] cation in mixtures of water and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]), an ionic liquid, at room temperature. A comparison of the results obtained from solutions made with H(2)O and with D(2)O highlights an anomalous conformational change in the D(2)O solution showing an extended N-shaped behavior. The gauche conformer of the [bmim] cation in D(2)O increased up to x = ~50 (D(2)O mol %); however, it decreased up to higher water concentrations of x = ~85 before again increasing drastically toward x = ~100. We provide spectroscopic evidence that the anomalous conformational dynamics of the [bmim] cation in D(2)O is directly related to the H/D exchange reaction of the C-H group at position 2 of the imidazolium ring.
Department of Applied Chemistry, National Defense Academy, Yokosuka, Kanagawa 239-8686, Japan.
Naohiro
N
Hatano
Mayuko
M
Watanabe
Takahiro
T
Takekiyo
Hiroshi
H
Abe
Yukihiro
Y
Yoshimura
D017666:Deuterium Oxide / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D008968:Molecular Conformation
C419324:1-butyl-3-methylimidazolium tetrafluoroborate; D007093:Imidazoles; D017666:Deuterium Oxide