| Full text | |
| Author(s): |
Bernardino, Kalil
;
Ribeiro, Mauro C. C.
Total Authors: 2
|
| Document type: | Journal article |
| Source: | VIBRATIONAL SPECTROSCOPY; v. 120, p. 9-pg., 2022-05-01. |
| Abstract | |
The strong cation-anion interaction in the protic ionic liquid 1-ethylimidazolium nitrate, [C(2)im][NO3], is revealed in different regions of the infrared spectrum (IR). The IR band related to the anion asymmetric stretching mode nu(as)(NO3) splits due to degeneracy lifting, the symmetry forbidden symmetric stretching mode nu(s)(NO3) acquires significant IR activity, and the cation v(N-H) stretching mode produces a broad band characteristic of strong hydrogen bond (H-bond). At high temperatures (up to 120 ?C), these spectral features remain in the IR spectrum, indicating the strong cation-anion interaction. The size of the nu(as)(NO3) splitting, the relative strength of nu(s)(NO3), and the intermolecular H-bond stretching mode nu(N-H center dot center dot center dot O) seen in the far-IR range are all accounted for in a quantum chemistry calculation of an ionic pair. The complex spectral pattern in the high-frequency range of the IR spectrum, where N-H and C-H stretching modes occur in overlapping bands, can be explained using a simple model coupling the nu(N-H) and nu(N-H center dot center dot center dot O) modes. The parameters of the model, including the dependence of the nu(N-H) frequency on the N center dot center dot center dot O distance of the H-bond, are also derived from the ionic pair calculation. The IR spectrum thus gives experimental evidence that using an ionic pair to explore the H-bond influence on the electronic structure of [C(2)im][NO3] is reasonable. (AU) | |
| FAPESP's process: | 17/12063-8 - Non-equilibrium molecular dynamics of ionic liquids |
| Grantee: | Kalil Bernardino |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| FAPESP's process: | 16/21070-5 - Vibrational spectroscopy with spatial resolution |
| Grantee: | Mauro Carlos Costa Ribeiro |
| Support Opportunities: | Research Projects - Thematic Grants |