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Temperature depende...
Temperature dependence of 1H NMR chemical shifts and diffusivity of confined ethylammonium nitrate ionic liquid
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- Gnezdilov, Oleg I. (författare)
- Kazan Federal University, 420008 Kazan, Russia
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- Antzutkin, Oleg N. (författare)
- Luleå tekniska universitet,Kemiteknik,Department of Physics, Warwick University, Coventry CV4 7AL, UK
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- Gimatdinov, Rustam (författare)
- Kazan State Medical University, 420012 Kazan, Russia
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- Filippov, Andrei, PhD, 1957- (författare)
- Luleå tekniska universitet,Kemiteknik,Kazan State Medical University, 420012 Kazan, Russia
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(creator_code:org_t)
- Elsevier, 2020
- 2020
- Engelska.
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Ingår i: Magnetic Resonance Imaging. - : Elsevier. - 0730-725X .- 1873-5894. ; 74, s. 84-89
- Relaterad länk:
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https://doi.org/10.1...
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https://doi.org/10.1...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Some ionic liquids (ILs) change their dynamic properties when placed in a confinement between polar surfaces (Filippov et al., Phys. Chem. Chem. Phys. 2018, 20, 6316). The diffusivities of ions and NMR relaxation times in these ILs also reversibly change under a strong static magnetic field. The mechanisms of these phenomena are not clear, but it has been suggested that they involve modified hydrogen-bonding networks formed in these ILs in the presence of polar surfaces. To obtain a better understanding of these effects, we performed temperature-dependent measurements of chemical shifts and diffusion coefficients for ethylammonium nitrate (EAN) IL in the bulk phase (IB) and confined in layers with a thickness of ~4 μm between quartz plates unexposed (I phase) and exposed (IMF phase) to a static magnetic field of 9.4 T. It was shown that the NMR chemical shift of NH3 protons of EAN in the I phase is strongly shifted upfield, ~0.0145 ppm/K, which is due to weakening of the hydrogen-bonding network of the confined EAN. Exposure to the magnetic field leads to restitution of the hydrogen-bonding (H-bonding network). The temperature dependences of diffusion coefficients follow the order D(I) > D(IB) > D(IMF) and can be described by a Vogel-Fulcher-Tammann approach with variation of the pre-exponential factor, which is determined by the strength of the H-bonding network. Confinement of EAN between plates (IB → I) is an endothermic process, while processes occurring in a magnetic field, I → IMF and IMF → I, are exothermic and endothermic, respectively.
Ämnesord
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Nyckelord
- Diffusion
- Ion dynamics
- Phase transformations
- Restricted diffusion
- Magnetic field
- Chemistry of Interfaces
- Gränsytors kemi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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