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Probing Microenvironment in Ionic Liquids by Time-Resolved EPR of Photoexcited Triplets Full article

Journal The Journal of Physical Chemistry B
ISSN: 1520-6106 , E-ISSN: 1520-5207
Output data Year: 2015, Volume: 119, Number: 42, Pages: 13440-13449 Pages count : 10 DOI: 10.1021/acs.jpcb.5b06792
Tags Ionic liquids; Magnetic resonance; Organic solvents; Paramagnetic resonance; Polarization; Probes; Solvents; Spin dynamics; Spin polarization
Authors Ivanov M.Yu. 1,2 , Veber S.L. 1,2 , Prikhodʹko S.A. 3 , Adonin N.Yu. 3 , Bagryanskaya E.G. 1,2,4 , Fedin M.V. 1,2
Affiliations
1 International Tomography Center SB RAS, 630090, Novosibirsk, Russia
2 Novosibirsk State University, 630090 Novosibirsk, Russia
3 Boreskov Institute of Catalysis SB RAS, 630090 Novosibirsk, Russia
4 N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia

Funding (1)

1 Russian Science Foundation 14-13-00826

Abstract: Unusual physicochemical properties of ionic liquids (ILs) open vistas for a variety of new applications. Herewith, we investigate the influence of microviscosity and nanostructuring of ILs on spin dynamics of the dissolved photoexcited molecules. We use two most common ILs [Bmim]PF6 and [Bmim]BF4 (with its close analogue [C10mim]BF4) as solvents and photoexcited Zn tetraphenylporphyrin (ZnTPP) as a probe. Time-resolved electron paramagnetic resonance (TR EPR) is employed to investigate spectra and kinetics of spin-polarized triplet ZnTPP in the temperature range 100–270 K. TR EPR data clearly indicate the presence of two microenvironments of ZnTPP in frozen ILs at 100–200 K, being manifested in different spectral shapes and different spin relaxation rates. For one of these microenvironments TR EPR data is quite similar to those obtained in common frozen organic solvents (toluene, glycerol, N-methyl-2-pyrrolidone). However, the second one favors the remarkably slow relaxation of spin polarization, being much longer than in the case of common solvents. Additional experiments using continuous wave EPR and stable nitroxide as a probe confirmed the formation of heterogeneities upon freezing of ILs and complemented TR EPR results. Thus, TR EPR of photoexcited triplets can be effectively used for probing heterogeneities and nanostructuring in frozen ILs. In addition, the increase of polarization lifetime in frozen ILs is an interesting finding that might allow investigation of short-lived intermediates inaccessible otherwise
Cite: Ivanov M.Y. , Veber S.L. , Prikhodʹko S.A. , Adonin N.Y. , Bagryanskaya E.G. , Fedin M.V.
Probing Microenvironment in Ionic Liquids by Time-Resolved EPR of Photoexcited Triplets
The Journal of Physical Chemistry B. 2015. V.119. N42. P.13440-13449. DOI: 10.1021/acs.jpcb.5b06792 WOS Scopus РИНЦ ANCAN PMID OpenAlex
Dates:
Submitted: Jul 15, 2015
Published online: Oct 7, 2015
Published print: Oct 22, 2015
Identifiers:
Web of science: WOS:000363916400023
Scopus: 2-s2.0-84945282663
Elibrary: 24966966
Chemical Abstracts: 2015:1588749
Chemical Abstracts (print): 163:553484
PMID: 26421723
OpenAlex: W2474081784
Citing:
DB Citing
Web of science 24
Scopus 24
Elibrary 21
OpenAlex 23
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