Probing the Local Structure of Pure Ionic Liquid Salts with Solid‐ and Liquid‐State NMR |
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Authors: | Peter G. Gordon Darren H. Brouwer Dr. John A. Ripmeester Dr. |
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Affiliation: | 1. National Research Council, Steacie Institute for Molecular Sciences, 100 Sussex Ave., Ottawa, ON, K1A 0R6 (Canada), Fax: (+1)?613‐998‐7833;2. Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6 (Canada) |
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Abstract: | 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. |
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Keywords: | chemical shifts computational chemistry ionic liquids NMR spectroscopy solid‐state structures |
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