TY - JOUR
T1 - Rotational and translational dynamics of N -butyl- N -methylpiperidinium trifluoromethanesulfonimide ionic liquids studied by NMR and MD simulations
AU - Han, Kee Sung
AU - Li, Song
AU - Hagaman, Edward W.
AU - Baker, Gary A.
AU - Cummings, Peter
AU - Dai, Sheng
PY - 2012/10/4
Y1 - 2012/10/4
N2 - Translational and rotational dynamics of the room temperature ionic liquid N-butyl-N-methylpiperidinium trifluoromethanesulfonimide, [C 4mpip] [Tf 2N], were investigated by 1H, 19F, and 13C nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulation. 1H NMR and MD results for the temperature-dependent diffusion coefficients, D, spin-lattice relaxation times, T 1, and rotational correlation times, τ c, for each site in the cation of [C 4mpip][Tf 2N] are in good agreement. The T 1 data indicate a long N-CH 3 group rotation time, comparable to the overall molecular reorientation time. Correlation time comparisons between 1-butyl-3-methylimidazolium RTILs with different anions (Cl -, PF 6 -, Tf 2N -) argue against invoking hydrogen bond interactions between the N-CH 3 hydrogens and the electron rich center of the anion as an explanation of the long N-CH 3 rotation times. Correlation time comparisons between piperidinium and pyrrolidinium RTILs with a common anion (Tf 2N -) suggest that correlation times for N-CH 3 rotation are primarily a function of the local structure of the cation.
AB - Translational and rotational dynamics of the room temperature ionic liquid N-butyl-N-methylpiperidinium trifluoromethanesulfonimide, [C 4mpip] [Tf 2N], were investigated by 1H, 19F, and 13C nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulation. 1H NMR and MD results for the temperature-dependent diffusion coefficients, D, spin-lattice relaxation times, T 1, and rotational correlation times, τ c, for each site in the cation of [C 4mpip][Tf 2N] are in good agreement. The T 1 data indicate a long N-CH 3 group rotation time, comparable to the overall molecular reorientation time. Correlation time comparisons between 1-butyl-3-methylimidazolium RTILs with different anions (Cl -, PF 6 -, Tf 2N -) argue against invoking hydrogen bond interactions between the N-CH 3 hydrogens and the electron rich center of the anion as an explanation of the long N-CH 3 rotation times. Correlation time comparisons between piperidinium and pyrrolidinium RTILs with a common anion (Tf 2N -) suggest that correlation times for N-CH 3 rotation are primarily a function of the local structure of the cation.
UR - https://www.scopus.com/pages/publications/84867153763
U2 - 10.1021/jp3069283
DO - 10.1021/jp3069283
M3 - Article
AN - SCOPUS:84867153763
SN - 1932-7447
VL - 116
SP - 20779
EP - 20786
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 39
ER -