Interaction between the pi-system of toluene and the imidazolium ring of ionic liquids: a combined NMR and molecular simulation study.
The solute-solvent interactions and the site-site distances between toluene and ionic liquids (ILs) 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [BMMIm][NTf2] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIm][NTf2] at various molar ratios were determined by NMR experiments (1D NMR, rotating-frame Overhauser effect spectroscopy (ROESY)) and by molecular simulation using an atomistic force field. The difference in behavior of toluene in these ILs has been related to the presence of H-bonding between the C2-H and the anion in [BMIm][NTf2] generating a stronger association (>20 kJ.mol-1) than in the case of [BMMIm][NTf2]. Consequently, toluene cannot cleave this H-bond in [BMIm][NTf2] which remains in large aggregates of ionic pairs. However, toluene penetrates the less strongly bonded network of [BMMIm][NTf2] and interacts with [BMMIm] cations.
Gutel
Thibaut
T
Université de Lyon, Institut de Chimie de Lyon, Equipe Chimie Organométallique de Surface, France.
Santini
Catherine C
CC
Pádua
Agilio A H
AA
Fenet
Bernard
B
Chauvin
Yves
Y
Canongia Lopes
José N
JN
Bayard
Francois
F
Costa Gomes
Margarida F
MF
Pensado
Alfonso
A