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Borovkov VI, Potashov PA, Beregovaya IV, Shchegoleva LN, Molin YN. Primary Radical Cations in Irradiated Poly(isobutylene). J Phys Chem B 2020; 124:7059-7066. [PMID: 32678602 DOI: 10.1021/acs.jpcb.0c03280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using the method of time-resolved magnetic field effect in radiation-induced fluorescence, primary radical cations (RCs) in irradiated poly(isobutylene) (PIB) have been detected for the first time. A comparison of experimental results with the data of quantum chemical calculations suggests that the initial geometry of the ionized fragment of the PIB molecule is close to the geometry of the neutral polymer in the trans-gauche-trans-gauche conformation. The spin density of the RC in this geometry is delocalized over more than 10 polymer units, and the width of the RC's EPR spectrum is about ΔHpp ≈ 1.3 mT. At a temperature of 273 K and lower, the lifetime of the primary RCs with the delocalized spin density exceeds 10 ns. The structural relaxation of the RCs results in the spin density localization on a single C-C bond, which is extended to nearly 0.2 nm, and in the increase in the EPR spectrum width to ΔHpp ≈ 2.4 mT. It looks likely that this intramolecular structural relaxation is coupled strongly with those types of molecular motions that determine the process of dielectric β-relaxation in the polymer.
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Affiliation(s)
- Vsevolod I Borovkov
- Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, 3, Institutskaya str., 630090 Novosibirsk, Russia.,Novosibirsk State University, 2, Pirogova str., Novosibirsk 630090, Russia
| | - Pavel A Potashov
- Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, 3, Institutskaya str., 630090 Novosibirsk, Russia.,Novosibirsk State University, 2, Pirogova str., Novosibirsk 630090, Russia
| | - Irina V Beregovaya
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, 9, Akad. Lavrent'ev Avenue, Novosibirsk 630090, Russia
| | - Lyudmila N Shchegoleva
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, 9, Akad. Lavrent'ev Avenue, Novosibirsk 630090, Russia
| | - Yuri N Molin
- Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, 3, Institutskaya str., 630090 Novosibirsk, Russia
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Melnikov AR, Verkhovlyuk VN, Kalneus EV, Korolev VV, Borovkov VI, Sherin PS, Davydova MP, Vasilevsky SF, Stass DV. Estimation of the Fraction of Spin-Correlated Radical Ion Pairs in Irradiated Alkanes using Magnetosensitive Recombination Luminescence from Exciplexes Generated upon Recombination of a Probe Pair. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/zpch-2016-0819] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
We suggest a convenient probe exciplex system for studies in radiation spin chemistry based on a novel acceptor-substituted diphenylacetylene, 1-(phenylethynyl)-4-(trifluoromethyl)benzene that has a very short fluorescence lifetime (<200 ps) and low quantum yield (0.01) of intrinsic emission, provides efficient electron capture in alkanes and efficient exciplex formation upon recombination in pair with DMA radical cation, while exhibiting a shifted to red exciplex emission band as compared to the parent system DMA – diphenylacetylene. After chemical, luminescent, radiation and spin-chemical characterization of the new system we used the magnitude of magnetic field effect in its exciplex emission band for experimental estimation of the fraction of spin-correlated radical ion pairs under X-irradiation with upper energy cutoff 40 keV in a set of 11 alkanes. For linear and branched alkanes magnetic field effects and the corresponding fractions are approximately 19–20% and 0.28, while for cyclic alkanes they are lower at 16–17% and 0.22, respectively.
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Affiliation(s)
- Anatoly R. Melnikov
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090 Novosibirsk, Russian Federation
- Novosibirsk State University, 2, Pirogova Str., 630090 Novosibirsk, Russian Federation
| | - Vladimir N. Verkhovlyuk
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090 Novosibirsk, Russian Federation
| | - Evgeny V. Kalneus
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090 Novosibirsk, Russian Federation
| | - Valeri V. Korolev
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090 Novosibirsk, Russian Federation
| | - Vsevolod I. Borovkov
- Novosibirsk State University, 2, Pirogova Str., 630090 Novosibirsk, Russian Federation
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090, Russian Federation
| | - Peter S. Sherin
- Novosibirsk State University, 2, Pirogova Str., 630090 Novosibirsk, Russian Federation
- International Tomography Center SB RAS, 3a, Institutskaya Str., 630090 Novosibirsk, Russian Federation
| | - Maria P. Davydova
- Novosibirsk State University, 2, Pirogova Str., 630090 Novosibirsk, Russian Federation
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090, Russian Federation
| | - Sergei F. Vasilevsky
- Novosibirsk State University, 2, Pirogova Str., 630090 Novosibirsk, Russian Federation
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090, Russian Federation
| | - Dmitri V. Stass
- Novosibirsk State University, 2, Pirogova Str., 630090 Novosibirsk, Russian Federation
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 3, Institutskaya Str., 630090, Russian Federation
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Melnikov AR, Kalneus EV, Korolev VV, Dranov IG, Kruppa AI, Stass DV. Highly efficient exciplex formation via radical ion pair recombination in X-irradiated alkane solutions for luminophores with short fluorescence lifetimes. Photochem Photobiol Sci 2014; 13:1169-79. [DOI: 10.1039/c3pp50432h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
X-irradiation of an alkane solution of N,N-dimethylaniline and diphenylacetylene (τf = 8 ps) produces an exciplex and yields a magnetic field effect of 20% in the exciplex emission band.
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Affiliation(s)
- Anatoly R. Melnikov
- Institute of Chemical Kinetics and Combustion SB RAS
- 630090 Novosibirsk, Russian Federation
- Novosibirsk State University
- 630090 Novosibirsk, Russian Federation
| | - Evgeny V. Kalneus
- Institute of Chemical Kinetics and Combustion SB RAS
- 630090 Novosibirsk, Russian Federation
| | - Valeri V. Korolev
- Institute of Chemical Kinetics and Combustion SB RAS
- 630090 Novosibirsk, Russian Federation
| | - Igor G. Dranov
- Institute of Chemical Kinetics and Combustion SB RAS
- 630090 Novosibirsk, Russian Federation
| | - Alexander I. Kruppa
- Institute of Chemical Kinetics and Combustion SB RAS
- 630090 Novosibirsk, Russian Federation
| | - Dmitri V. Stass
- Institute of Chemical Kinetics and Combustion SB RAS
- 630090 Novosibirsk, Russian Federation
- Novosibirsk State University
- 630090 Novosibirsk, Russian Federation
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Shkrob IA, Sauer MC, Trifunac AD. Radiation chemistry of organic liquids: Saturated hydrocarbons. RADIATION CHEMISTRY - PRESENT STATUS AND FUTURE TRENDS 2001. [DOI: 10.1016/s0167-6881(01)80011-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Morozov V, Gorelik E, Lukzen N, Sagdeev R, Anishchik S. Manifestation of ion-molecular charge transfer in the kinetics of microwave field effect on recombination fluorescence. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)00698-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Anishchik S, Borovkov V, Ivannikov V, Shebolaev I, Chernousov Y, Lukzen N, Anisimov O, Molin Y. Microwave field effects on the time dependence of recombination fluorescence from non-polar solutions. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00021-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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