Molecular mobility in several imidazolium-based ionic liquids according to data of 1 H and 13 C NMR relaxation

Vladimir V Matveev; Denis A Markelov; Alexandr V Ievlev; Ekaterina A Brui; Konstantin V Tyutyukin; Erkki Lähderanta

doi:10.1002/mrc.4681

Molecular mobility in several imidazolium-based ionic liquids according to data of ¹ H and ¹³ C NMR relaxation

Magn Reson Chem. 2018 Feb;56(2):140-143. doi: 10.1002/mrc.4681. Epub 2017 Dec 3.

Authors

Vladimir V Matveev¹, Denis A Markelov¹, Alexandr V Ievlev^{1

2}, Ekaterina A Brui^{1

3}, Konstantin V Tyutyukin¹, Erkki Lähderanta²

Affiliations

¹ Physical Faculty, Saint Petersburg State University, 7/9 Universitetskaya nab, Saint Petersburg, 199034, Russia.
² Laboratory of Physics, Lappeenranta University of Technology, Box 20, 53851, Lappeenranta, Finland.
³ Engineering and Physical Faculty, Saint Petersburg National Research University of Information Technologies, Mechanics and Optics, Kronverkskiy pr. 49, Saint Petersburg, 197101, Russia.

PMID: 29127740
DOI: 10.1002/mrc.4681

Abstract

Temperature dependences are compared for ¹ H and ¹³ C NMR 1/T₁ curves relaxation rates in three imidazolium-based ionic liquids (ILs), namely, in [bmim]PF₆ , [bmim]BF₄ , and [emim]CH₃ COO. ¹³ C curves show alike behavior for all three ILs and follow a well-known Bloembergen-Pound-Purcell (BPP) equation. On the contrary, an essential part of ¹ H curves differ strongly from corresponding ¹³ C ones and also have different shapes for different ILs. For the first time, we have detected the specific, two-maximum shape of ¹ H relaxation curve for hydrogen atom of C(2)H group of the [emim]CH₃ COO. Assuming that this maximum reflects the correlated rotation of several adjoining ion pairs, we have tried to destroy this rotation by addition of glycerol to the [emim]CH₃ COO. The second, high-temperature maximum has disappeared in the [emim]CH₃ COO-glycerol mixture, and this fact confirms our assumption. Copyright © 2017 John Wiley & Sons, Ltd.

Keywords: NMR relaxation; emimOAc; glycerol; ionic liquids; temperature dependence.

Publication types

Research Support, Non-U.S. Gov't