Journal article
Stepwise Conformational Disorder in an Ionic Plastic Crystal
The journal of physical chemistry. B, v 129(18), pp 4465-4472
25 Apr 2025
PMID: 40279544
Abstract
Structural changes associated with the phase transitions of choline bis(trifluoromethanesulfonyl)imide, [Chol][NTf2], were revealed using Raman spectroscopy in situ with differential scanning calorimetry (DSC) measurements. Raman bands probed along the calorimetric measurements identifying the gauche or anti conformers of [Chol] and the transoid or cisoid conformers of [NTf2]. The gauche conformer of [Chol] and the transoid conformer of [NTf2] are present in the low-temperature crystal. The disorder in the plastic crystal phase of [Chol][NTf2] is linked to the conformational flexibility acquired by [Chol], while [NTf2] preserves the same conformation as in the low-temperature crystal. The decoupling in the conformational dynamics between [Chol] and [NTf2] in the plastic crystal is found from Raman spectra obtained during heating or cooling DSC measurements. Such separate conformational dynamics persist along the second solid–solid transition seen in the DSC heating curve, with [NTf2] gaining conformational flexibility only after melting. The low-frequency range was probed by Raman and inelastic neutron scattering (INS) spectroscopies. Owing to the intense quasi-elastic scattering tail in the Raman spectra resulting from fast relaxations, the plastic crystal’s low-frequency Raman spectra resemble liquid phase spectra. Based on infrared spectra in the high-frequency range related to the ν(OH) stretching mode, the cation–cation hydrogen bond structural motif, which is alleged to exist in the liquid phase yet absent in the low-temperature crystal, is found to be present already in the plastic crystal phase of [Chol][NTf2].
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Details
- Title
- Stepwise Conformational Disorder in an Ionic Plastic Crystal
- Creators
- Letícia A. Souza - Universidade de São PauloThamires A. Lima - Drexel University, Chemical and Biological EngineeringVitor H. Paschoal - Wrocław University of Science and TechnologyLuke L. Daemen - Oak Ridge National LaboratoryY. Z - University of MichiganAbner M. Sampaio - Universidade de São PauloMauro C. C. Ribeiro - Universidade de São Paulo
- Publication Details
- The journal of physical chemistry. B, v 129(18), pp 4465-4472
- Publisher
- American Chemical Society
- Number of pages
- 8
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:001477157500001
- Scopus ID
- 2-s2.0-105003753063
- Other Identifier
- 991022049009404721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Chemistry, Physical