Computational insights into the molecular interaction and ion-pair structures of a novel zinc-functionalized ionic liquid, [Emim][Zn(TFSI)₃].
The ion pair structures of a novel CO2 capture material in the form of a metal chelate anion-containing room temperature ionic liquid (IL), 1-ethyl-3-methylimidazolium tri[bis(trifluoromethylsulfonyl)imide]zincate(II), [Emim][Zn(TFSI)3], were elucidated by correlating the infrared spectra generated using density functional theory (DFT) calculations with the experimental spectrum derived from a room temperature infrared spectroscopic measurement. A free volume energy minimization algorithm revealed stable structures where the zinc ion forms an octahedral, homoleptic complex with the ligand bis(trifluoromethylsulfonyl)imide through coordination with the oxygen of the sulfone group, with 1-ethyl-3-methylimidazolium acting as the counterion. The method of analysis was built around 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [Emim][TFSI], involving direct comparison with published data, and extended to the more complex [Emim][Zn(TFSI)3] system. The DFT calculations reproduced the vibrational spectra of [Emim][Zn(TFSI)3] and [Emim][TFSI] using their optimized geometries, with correlation slopes of 0.9996 and 1.0022, respectively. Comparison of the vibrational modes of [Emim][TFSI] and [Emim][Zn(TFSI)3] provided insights into the ion pair structure of, and molecular interactions in the ILs analyzed.
Center for Molecular and Materials Sciences, Sansom Institute, University of South Australia, Adelaide, SA 5000, Australia; CSIRO Energy Flagship, Box 312, Clayton South, VIC 3169, Australia.
Ian Harvey
IH
Arellano
CSIRO Energy Flagship, Box 312, Clayton South, VIC 3169, Australia.
Junhua
J
Huang
Center for Molecular and Materials Sciences, Sansom Institute, University of South Australia, Adelaide, SA 5000, Australia. Electronic address: phillip.pendleton@unisa.edu.au.
Phillip
P
Pendleton
DFT; Infrared spectroscopy; Interaction; Ionic liquid; Structure