Influence of the Electric Charge of Spin Probes on Their Diffusion in Room-Temperature Ionic Liquids

B Y Mladenova Kattnig; N A Chumakova; D R Kattnig; I A Grigor'ev; G Grampp; A I Kokorin

doi:10.1021/acs.jpcb.1c02493

Influence of the Electric Charge of Spin Probes on Their Diffusion in Room-Temperature Ionic Liquids

J Phys Chem B. 2021 Aug 19;125(32):9235-9243. doi: 10.1021/acs.jpcb.1c02493. Epub 2021 Aug 11.

Authors

B Y Mladenova Kattnig¹, N A Chumakova^{2

3}, D R Kattnig¹, I A Grigor'ev⁴, G Grampp⁵, A I Kokorin^{2

6}

Affiliations

¹ Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, U.K.
² N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Science, Kosygin St. 4, Moscow 119991, Russia.
³ Chemistry Department, M.V. Lomonosov Moscow State University, Leninskiye Gory, 1/3, Moscow 119991, Russia.
⁴ N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave., 9, Novosibirsk 630090, Russia.
⁵ Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz 8010, Austria.
⁶ Plekhanov Russian University of Economics, Moscow 115093, Russia.

PMID: 34378388
DOI: 10.1021/acs.jpcb.1c02493

Abstract

The rotational and translational diffusion of negatively charged and uncharged spin probes in five imidazolium-based room-temperature ionic liquids (RTILs), 1-ethyl-3-methylimidazolium tetrafluoroborate, emimBF₄, 1-butyl-3-methylimidazolium tetrafluoroborate, bmimBF₄, 1-octyl-3-methylimidazolium tetrafluoroborate, omimBF₄, 1-octyl-3-methylimidazolium hexafluorophosphate, omimPF₆, and 1-octyl-3-methylimidazolium chloride, omimCl, has been studied by means of electron paramagnetic resonance spectroscopy. Detailed analyses of the spin-Hamiltonian parameters and spin exchange interactions have been carried out. The temperature dependences of the line broadening induced by the electronic dipole-dipole interaction and the electron spin exchange coupling are determined. The translational mobility of spin probes is semiquantitatively characterized and successfully explained in the framework of a hypothesis based on the assumption of polar and unpolar domains within the RTILs.