Dynamical heterogeneities in ionic liquids as revealed from deuteron NMR
| Autor: | Alexander G. Stepanov, Dietmar Paschek, Andreas Appelhagen, Viviane Overbeck, Anne-Marie Bonsa, Alexander E. Khudozhitkov, Ralf Ludwig, Peter Stange, Daniil I. Kolokolov |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Relaxation (NMR) Metals and Alloys Ionic bonding 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Catalysis 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Viscosity chemistry.chemical_compound chemistry Solid-state nuclear magnetic resonance Chemical physics Phase (matter) Ionic liquid Materials Chemistry Ceramics and Composites 0210 nano-technology Anisotropy Spectroscopy |
| Zdroj: | Chemical Communications. 54:3098-3101 |
| ISSN: | 1364-548X 1359-7345 |
| DOI: | 10.1039/c7cc09440j |
| Popis: | The heterogeneity in dynamics has important consequences for understanding the viscosity, diffusion, ionic mobility, and the rates of chemical reactions in technology relevant systems such as polymers, metallic glasses, aqueous solutions, and inorganic materials. Herein, we study the spatial and dynamic heterogeneities in ionic liquids by means of solid state NMR spectroscopy. In the 2H spectra of the protic ionic liquid [TEA][OTf] we observe anisotropic and isotropic signals at the same time. The spectra measured below the melting temperature at 306 K could be simulated by a superposition of the solid and liquid line shapes, which provided the transition enthalpies between the rigid and mobile fractions. Consequently, we measured the spin-lattice relaxation times T1 for the anisotropic and the isotropic signals for the temperature range between 203 and 436 K. Both dispersion curves could be fitted to models including rotational correlation times, activation barriers and rate constants. This approach allowed determining the rotational correlation times for the N-D molecular vector of the [TEA]+ cation in differently mobile environments. The mobility is only slightly different, as indicated by small differences in activation energies for these processes. The NMR correlation times for the highly mobile phase are linearly related to measured viscosities, which supports the applicability of the Stokes-Einstein-Debye relation. |
| Databáze: | OpenAIRE |
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