KFU. Card publication. Temperature dependence of 1H NMR chemical shifts and diffusivity of confined ethylammonium nitrate ionic liquid

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TEMPERATURE DEPENDENCE OF 1H NMR CHEMICAL SHIFTS AND DIFFUSIVITY OF CONFINED ETHYLAMMONIUM NITRATE IONIC LIQUID

Form of presentation

Articles in international journals and collections

Year of publication

2020

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Authors, employees of KFU

Gnezdilov Oleg Ivanovich, author

Filippov Andrey Vasilevich, author

Bibliographic description in the original language

Gnezdilov O.I, Antzutkin O.N, Gimatdinov R, Temperature dependence of 1H NMR chemical shifts and diffusivity of confined ethylammonium nitrate ionic liquid//Magnetic Resonance Imaging. - 2020. - Vol.74, Is.. - P.84-89.

Annotation

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 hydrogenbonding network of the confined EAN. Exposure to the magnetic field leads to restitution of the hydrogenbonding (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.

Keywords

ionic liquids, dynamic properties, diffusivities of ions, NMR relaxation, ethylammonium nitrate, Confinement of EAN, chemical shift, diffusion coefficients

The name of the journal

Magnetic Resonance Imaging

URL

https://doi.org/10.1016/j.mri.2020.09.012

Please use this ID to quote from or refer to the card

https://repository.kpfu.ru/eng/?p_id=240312&p_lang=2

Full metadata record

Field DC	Value	Language
dc.contributor.author	Gnezdilov Oleg Ivanovich	ru_RU
dc.contributor.author	Filippov Andrey Vasilevich	ru_RU
dc.date.accessioned	2020-01-01T00:00:00Z	ru_RU
dc.date.available	2020-01-01T00:00:00Z	ru_RU
dc.date.issued	2020	ru_RU
dc.identifier.citation	Gnezdilov O.I, Antzutkin O.N, Gimatdinov R, Temperature dependence of 1H NMR chemical shifts and diffusivity of confined ethylammonium nitrate ionic liquid//Magnetic Resonance Imaging. - 2020. - Vol.74, Is.. - P.84-89.	ru_RU
dc.identifier.uri	https://repository.kpfu.ru/eng/?p_id=240312&p_lang=2	ru_RU
dc.description.abstract	Magnetic Resonance Imaging	ru_RU
dc.description.abstract	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 hydrogenbonding network of the confined EAN. Exposure to the magnetic field leads to restitution of the hydrogenbonding (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.	ru_RU
dc.language.iso	ru	ru_RU
dc.subject	ionic liquids	ru_RU
dc.subject	dynamic properties	ru_RU
dc.subject	diffusivities of ions	ru_RU
dc.subject	NMR relaxation	ru_RU
dc.subject	ethylammonium nitrate	ru_RU
dc.subject	Confinement of EAN	ru_RU
dc.subject	chemical shift	ru_RU
dc.subject	diffusion coefficients	ru_RU
dc.title	Temperature dependence of 1H NMR chemical shifts and diffusivity of confined ethylammonium nitrate ionic liquid	ru_RU
dc.type	Articles in international journals and collections	ru_RU