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Ivanov MY, Veber SL, Prikhod’ko SA, Adonin NY, Bagryanskaya EG, Fedin MV. Probing Microenvironment in Ionic Liquids by Time-Resolved EPR of Photoexcited Triplets. J Phys Chem B 2015; 119:13440-9. [DOI: 10.1021/acs.jpcb.5b06792] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Yu. Ivanov
- International
Tomography Center SB RAS, 630090, Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - S. L. Veber
- International
Tomography Center SB RAS, 630090, Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - S. A. Prikhod’ko
- Boreskov Institute of Catalysis SB RAS, 630090 Novosibirsk, Russia
| | - N. Yu. Adonin
- Boreskov Institute of Catalysis SB RAS, 630090 Novosibirsk, Russia
| | - E. G. Bagryanskaya
- International
Tomography Center SB RAS, 630090, Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
- N. N. Vorozhtsov
Novosibirsk Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - M. V. Fedin
- International
Tomography Center SB RAS, 630090, Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
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Time-Resolved Electron Paramagnetic Resonance Spectroscopy. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2013. [DOI: 10.1016/b978-0-12-407754-6.00001-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Goez M. Elucidating organic reaction mechanisms using photo-CIDNP spectroscopy. Top Curr Chem (Cham) 2012; 338:1-32. [PMID: 22911487 DOI: 10.1007/128_2012_348] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
CIDNP (chemically induced dynamic nuclear polarization) arises in radical pairs or biradicals but is detected in the diamagnetic reaction products. Hence, it can be used not only to identify and characterize both types of species but also to establish the pathways connecting precursors, paramagnetic intermediates and products, and to employ the polarizations as labels to individual nuclei. Recent applications of CIDNP to elucidate the mechanisms of photochemical reactions are reviewed, which illustrate all these facets.
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Affiliation(s)
- Martin Goez
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120, Halle/Saale, Germany,
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Caregnato P, Jarocha LE, Esinhart HS, Lebedeva NV, Tarasov VF, Forbes MDE. Electrostatic control of spin exchange between mobile spin-correlated radical pairs created in micellar solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5304-5309. [PMID: 21476533 DOI: 10.1021/la2005997] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A series of photoinduced H-atom abstraction reactions between anthraquinone-2,6,-disulfonate, disodium salt (AQDS) and differently charged micellar substrates is presented. After a 248 nm excimer laser flash, the first excited triplet state of AQDS is rapidly formed and then quenched by abstraction of a hydrogen atom from the alkyl chain of the micelle surfactant, leading to a spin-correlated radical pair (SCRP). The SCRP is detected 500 ns after the laser flash using time-resolved (direct detection) electron paramagnetic resonance (TREPR) spectroscopy at X-band (9.5 GHz). By changing the charge on the surfactant headgroup from negative (sodium dodecyl sulfate, SDS) to positive (dodecyltrimethylammonium chloride, DTAC), TREPR spectra with different degrees of antiphase structure (APS) in their line shape were observed. The first derivative-like APS line shape is the signature of an SCRP experiencing an electron spin exchange interaction between the radical centers, which was clearly observable in DTAC micelles and absent in SDS micellar solutions. Solutions with surfactant concentrations well below the critical micelle concentration (cmc) or solutions where micellar formation had been disrupted (1:1 v/v CH(3)CN/H(2)O) also showed no APS line shapes in their TREPR spectra. These results support the conclusion that electrostatic forces between the sensitizer (AQDS) charge and the substrate (surfactant) headgroup charge are responsible for the observed effects. The results represent a new example of electrostatic control of a spin exchange interaction in mobile radical pairs.
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Affiliation(s)
- Paula Caregnato
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de la Plata, C.C. 16, suc. 4, (1900) La Plata, Argentina
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Penwell SB, Wright JC. Multiresonant Coherent Multidimensional Spectroscopy of the Vibrationally Induced Decarboxylation of AOT: Deuterium Oxide Reverse Micelles. J Phys Chem B 2011; 115:5564-73. [DOI: 10.1021/jp111386y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Samuel B. Penwell
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - John C. Wright
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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Hunyadi Murph SE, Serkiz SM, Fox EB, Colon-Mercado H, Sexton L, Siegfried M. Synthesis, Functionalization, Characterization, and Application of Controlled Shape Nanoparticles in Energy Production. ACS SYMPOSIUM SERIES 2011. [DOI: 10.1021/bk-2011-1064.ch008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Simona E. Hunyadi Murph
- National and Homeland Security, Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808
| | - Steven M. Serkiz
- National and Homeland Security, Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808
| | - Elise B. Fox
- National and Homeland Security, Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808
| | - Hector Colon-Mercado
- National and Homeland Security, Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808
| | - Lindsay Sexton
- National and Homeland Security, Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808
| | - Matthew Siegfried
- National and Homeland Security, Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808
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Miura T, Kageyama A, Torii S, Murai H. Photoreactions and Molecular Dynamics of Radical Pairs in a Reversed Micelle Studied by Time-Resolved Measurements of EPR and Magnetic Field Effect. J Phys Chem B 2010; 114:14550-8. [DOI: 10.1021/jp102300z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomoaki Miura
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Atsushi Kageyama
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Sakiko Torii
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Hisao Murai
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
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Krumkacheva OA, Gorelik VR, Bagryanskaya EG, Lebedeva NV, Forbes MDE. Supramolecular photochemistry in beta-cyclodextrin hosts: a TREPR, NMR, and CIDNP investigation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8971-8980. [PMID: 20192161 DOI: 10.1021/la904788t] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A systematic investigation of the photochemistry and ensuing radical chemistry of three guest ketones encapsulated in randomly methylated beta-cyclodextrin (beta-CD) hosts is reported. Dibenzyl ketone (DBK), deoxybenzoin (DOB), and benzophenone (BP) triplet states are rapidly formed after photolysis at 308 nm. Time-resolved electron paramagnetic resonance (TREPR) spectroscopy, steady-state NMR spectroscopy, and time-resolved chemically induced nuclear polarization (TR-CIDNP) experiments were performed on the ketone/CD complexes and on the ketones in free solution for comparison. The major reactivity pathways available from these excited states are either Norrish I alpha-cleavage or H-atom abstraction from the interior of the CD capsule or the solvent. The DOB triplet state undergoes both reactions, whereas the DBK triplet shows exclusively alpha-cleavage and the BP triplet shows exclusively H-atom abstraction. Radical pairs are observed in beta-CDs by TREPR, consisting of either DOB or BP ketyl radicals with sugar radicals from the CD interior. The TREPR spectra acquired in CDs are substantially broadened due to strong spin exchange. The electron spin polarization mechanism is mostly due to S-T(0) radical pair mechanism (RPM) in solution but changes to S-T(-) RPM in the CDs due to the large exchange interaction. The TR-CIDNP results confirm the reactivity patterns of all three ketones, and DOB shows strong nuclear spin polarization from a novel rearrangement product resulting from the alpha-cleavage reaction.
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Ohara K, Hashimoto Y, Hamada C, Nagaoka SI. Time-resolved EPR investigation on the photoreactions of vitamin K with antioxidant vitamins in micelle systems. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Lebedeva NV, Gorelik EV, Prowatzke AM, Forbes MDE. Model systems for poly(acrylic acid) main-chain radicals based on the Kemp's triacid framework. J Phys Chem B 2008; 112:7574-80. [PMID: 18517241 DOI: 10.1021/jp712098j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Kemp's triacid (KTA) and cyclohexane tricarboxylic acid (CTA) are small-molecule model systems for acrylic acid polymers, having the same functionalities and stereoregularities as isotactic poly(methacrylic acid) (PMAA) and poly(acrylic acid) (PAA), respectively. As part of an ongoing investigation of radicals produced by photolysis of acrylic polymers, the photochemistry and free radicals from the model systems have been studied using time-resolved EPR spectroscopy as a function of temperature and pH. Radicals are created by direct photolysis of the acids at 248 nm or by sensitized photo-oxidation using quinone triplet states at 308 nm. The two methods of radical production lead to different chemically induced electron spin polarization (CIDEP) patterns in the ensuing radicals, which are simulated and discussed. Well-resolved spectra are obtained at all temperatures for the model system radicals, which are determined to be in the slow motion condition. DFT calculations of the model system radicals are presented and discussed in support of the experimental data.
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Affiliation(s)
- Natalia V Lebedeva
- Caudill Laboratories, CB # 3290, Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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