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Probing the Local Structure of Pure Ionic Liquid Salts with Solid‐ and Liquid‐State NMR
Author(s) -
Gordon Peter G.,
Brouwer Darren H.,
Ripmeester John A.
Publication year - 2010
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200900624
Subject(s) - ionic liquid , solid state nuclear magnetic resonance , chemistry , solid state , local structure , ionic bonding , nuclear magnetic resonance spectroscopy , liquid state , materials science , crystallography , organic chemistry , ion , nuclear magnetic resonance , physics , catalysis
Room‐temperature ionic liquids (RTILs) are gaining increasing interest and are considered part of the green chemistry paradigm due to their negligible vapour pressure and ease of recycling. Evidence of liquid‐state order, observed by IR and Raman spectroscopy, diffraction studies, and simulated by ab initio methods, has been reported in the literature. Here, quadrupolar nuclei are used as NMR probes to extract information about the solid and possible residual order in the liquid state of RTILs. To this end, the anisotropic nature and field dependence of quadrupolar and chemical shift interactions are exploited. Relaxation time measurements and a search for residual second‐order quadrupolar coupling were employed to investigate the molecular motions present in the liquid state and infer what kind of order is present. The results obtained indicate that on a timescale of ∼10 −8 sec or longer, RTILs behave as isotropic liquids without residual order.