Solvation and Rotational Diffusion of Solutes in Room Temperature Ionic Liquids as Studied by EPR Spectroscopy with Nitroxide Spin Probing Method

We report high-pressure (up to 50 MPa) ESR-spectroscopic investigations on the rotational correlation times of the nitroxide radicals 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL), and 4-amino-2,2,6,6-tetramethylpiperidine 1-oxyl (ATEMPO) in the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (emimBF 4 ), 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF 6 ), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF 4 ), 1-methyl-3-octylimidazolium tetrafluoroborate (omimBF 4 ), and 1-methyl-3-octylimidazolium hexafluorophosphate (omimPF 6 ). The activation volumes (38.5–56.6 Å 3 ) determined from pressure dependent rotational diffusion coefficients agree well with the pressure dependent viscosities of the ionic liquids. Experimentally, the fractional exponent of the generalized Stokes–Einstein–Debye relation is found to be close to one.

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“…Rotational motion of spin probes in imidazolium-based ionic liquids has been reported by Sengupta and Miyake as well. − …”

Section: Introductionmentioning

confidence: 75%

High-Pressure ESR Spectroscopy: On the Rotational Motion of Spin Probes in Pressurized Ionic Liquids

Kattnig

Grampp

2022

J. Phys. Chem. B

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“…The analysis of the temperature behavior of rotational correlation times for PADS, TEMPO, CProxyl – , CProxylH, and cholestane radicals in different RTILs showed that mostly τ rot values were within the range calculated on the basis of Stokes–Einstein–Debye hydrodynamic theory with stick and slip boundary conditions or described by the Gierer–Wirtz theory. There are a few exceptions revealed in the case of small probes in some RTILs containing BF 4 – and PF 6 – anions …”

Section: Introductionmentioning

confidence: 99%

“…There are a few exceptions revealed in the case of small probes in some RTILs containing BF 4 − and PF 6 − anions. 19 A dual probe, a pyrene chromophore covalently linked to an R 6 -radical via an ester bridge, was investigated by UV−vis, fluorescence, and EPR spectroscopy. 16 Molecular solvents of different polarities and RTILs with either imidazolium or pyrrolidinium cations and various anions((CF 3 SO 2 ) 2 N − , BF 4 − , P(C 2 F 5 ) 3 F 3 − , or N(CN) 2 − ) were studied.…”

Section: ■ Introductionmentioning

confidence: 99%

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

et al. 2021

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The rotational and translational diffusion of negatively charged and uncharged spin probes in five imidazolium-based room-temperature ionic liquids (RTILs), 1-ethyl-3methylimidazolium tetrafluoroborate, emimBF 4 , 1-butyl-3-methylimidazolium tetrafluoroborate, bmimBF 4 , 1-octyl-3-methylimidazolium tetrafluoroborate, omimBF 4 , 1-octyl-3-methylimidazolium hexafluorophosphate, omimPF 6 , 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.

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PPDN and NTCDA radical anions formation in EMIM-DCA, BMIM-BF4, EMIM-Ac ionic liquid solutions under the steady state UV and Vis light illumination: A combined X-, K-band EPR and DFT study

Ritter

Konkin

Knauer

et al. 2022

Journal of Molecular Liquids

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Solvation and Rotational Diffusion of Solutes in Room Temperature Ionic Liquids as Studied by EPR Spectroscopy with Nitroxide Spin Probing Method

Cited by 4 publications

References 35 publications

High-Pressure ESR Spectroscopy: On the Rotational Motion of Spin Probes in Pressurized Ionic Liquids

High-Pressure ESR Spectroscopy: On the Rotational Motion of Spin Probes in Pressurized Ionic Liquids

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

PPDN and NTCDA radical anions formation in EMIM-DCA, BMIM-BF4, EMIM-Ac ionic liquid solutions under the steady state UV and Vis light illumination: A combined X-, K-band EPR and DFT study

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