In:
The Journal of Chemical Physics, AIP Publishing, Vol. 137, No. 19 ( 2012-11-21)
Kurzfassung:
The rotational correlation times (τ2R) for polar water (D2O) molecule and apolar benzene (C6D6) molecule were determined in ionic liquids (ILs) by means of the 2H (D) NMR spin-lattice relaxation time (T1) measurements. The solvent IL was systematically varied to elucidate the anion and cation effects separately. Five species, bis(trifluoromethylsulfonyl)imide (TFSI−), trifluoromethylsulfonate (TfO−), hexafluorophosphate (PF6−), chloride (Cl−), and formate (HCOO−), were examined for the anion effect against a fixed cation species of 1-butyl-3-methyl-imidazolium (bmim+). Four species, bmim+, N-methyl-N-butylpyrrolidinium (bmpy+), N,N,N-trimethyl-N-propylammonium (N1,1,1,3+), and P,P,P-trihexyl-P-tetradecylphosphonium (P6,6,6,14+), were employed for the cation effect against a fixed anion species of TFSI−. The τ2R ratio of water to benzene, expressed as τW/B, was used as a probe to characterize the strength of Coulombic solute-solvent interaction in ILs beyond the hydrodynamic limit based on the excluded-volume effect. The τW/B value was found to strongly depend on the anion species, and the solute dynamics are sensitive not only to the size but also to the chemical structure of the component anion. The cation effect was rather weak, in contrast. The largest and most hydrophobic P6,6,6,14+ cation was exceptional and a large τW/B was observed, indicating a unique solvation structure in [P6,6,6,14+]-based ILs.
Materialart:
Online-Ressource
ISSN:
0021-9606
,
1089-7690
Sprache:
Englisch
Verlag:
AIP Publishing
Publikationsdatum:
2012
ZDB Id:
3113-6
ZDB Id:
1473050-9
