The nuclear Overhauser enhancement (NOE) is a powerful tool of NMR spectroscopy extensively used to gain structural information in ionic liquids (ILs). A general model for the distance dependence of intermolecular NOE in ILs was recently proposed showing that NOE spots beyond the first solvation shell and accounts for long-range effects. This conclusion prompted for a deep rethinking of the NOE data interpretation in ILs. In this paper we present an extensive and quantitative study of N-propyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR<inf>13</inf>TFSI), the homologue with bis(fluorosulfonyl)imide (PYR<inf>13</inf>FSI), and their mixtures with LiTFSI based on <sup>1</sup>H-<sup>19</sup>F and <sup>1</sup>H-<sup>7</sup>LiNOE correlation experiments (HOESY). The former is mainly tuned on long-range interactions, the latter on short-range ones, due to the small and large Larmor frequency differences of the involved nuclei. The collected data are discussed in two different way: long-range <sup>1</sup>H-<sup>19</sup>FNOEs spot on the polar/apolar domains within the ILs, whereas short-range (e.g. regarding the first coordination shell) <sup>1</sup>H-<sup>7</sup>LiNOEs describe the contacts between first neighbors, with interesting correlation with the distances' statistics derived by crystallographic data of related systems.
Castiglione, F., Appetecchi, G., Passerini, S., Panzeri, W., Indelicato, S., Mele, A. (2015). Multiple points of view of heteronuclear NOE: Long range vs short range contacts in pyrrolidinium based ionic liquids in the presence of Li salts. JOURNAL OF MOLECULAR LIQUIDS, 210, 215-222 [10.1016/j.molliq.2015.05.036].
Multiple points of view of heteronuclear NOE: Long range vs short range contacts in pyrrolidinium based ionic liquids in the presence of Li salts
INDELICATO, Serena;
2015-01-01
Abstract
The nuclear Overhauser enhancement (NOE) is a powerful tool of NMR spectroscopy extensively used to gain structural information in ionic liquids (ILs). A general model for the distance dependence of intermolecular NOE in ILs was recently proposed showing that NOE spots beyond the first solvation shell and accounts for long-range effects. This conclusion prompted for a deep rethinking of the NOE data interpretation in ILs. In this paper we present an extensive and quantitative study of N-propyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYRFile | Dimensione | Formato | |
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