1
|
|
2
|
Ivanov KL, Sadovsky VM, Lukzen NN. Theoretical description of spin-selective reactions of radical pairs diffusing in spherical 2D and 3D microreactors. J Chem Phys 2015; 143:084110. [PMID: 26328821 DOI: 10.1063/1.4928648] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we treat spin-selective recombination of a geminate radical pair (RP) in a spherical "microreactor," i.e., of a RP confined in a micelle, vesicle, or liposome. We consider the microreactor model proposed earlier, in which one of the radicals is located at the center of the micelle and the other one undergoes three-dimensional diffusion inside the micelle. In addition, we suggest a two-dimensional model, in which one of the radicals is located at the "pole" of the sphere, while the other one diffuses on the spherical surface. For this model, we have obtained a general analytical expression for the RP recombination yield in terms of the free Green function of two-dimensional diffusion motion. In turn, this Green function is expressed via the Legendre functions and thus takes account of diffusion over a restricted spherical surface and its curvature. The obtained expression allows one to calculate the RP recombination efficiency at an arbitrary magnetic field strength. We performed a comparison of the two models taking the same geometric parameters (i.e., the microreactor radius and the closest approach distance of the radicals), chemical reactivity, magnetic interactions in the RP and diffusion coefficient. Significant difference between the predictions of the two models is found, which is thus originating solely from the dimensionality effect: for different dimensionality of space, the statistics of diffusional contacts of radicals becomes different altering the reaction yield. We have calculated the magnetic field dependence of the RP reaction yield and chemically induced dynamic nuclear polarization of the reaction products at different sizes of the microreactor, exchange interaction, and spin relaxation rates. Interestingly, due to the intricate interplay of diffusional contacts of reactants and spin dynamics, the dependence of the reaction yield on the microreactor radius is non-monotonous. Our results are of importance for (i) interpreting experimental data for magnetic field effects on RP recombination in confined space and (ii) for describing kinetics of chemical reactions, which occur predominantly on the surfaces of biomembranes, i.e., lipid peroxidation reactions.
Collapse
Affiliation(s)
- Konstantin L Ivanov
- International Tomography Center, Siberian Branch, Russian Academy of Sciences, Institutskaya St. 3a, Novosibirsk 630090, Russia
| | - Vladimir M Sadovsky
- Institute of Computational Modeling, Siberian Branch, Russian Academy of Sciences, Akademgorodok 50/44, Krasnoyarsk 660036, Russia
| | - Nikita N Lukzen
- International Tomography Center, Siberian Branch, Russian Academy of Sciences, Institutskaya St. 3a, Novosibirsk 630090, Russia
| |
Collapse
|
3
|
Zarea M, Ratner MA, Wasielewski MR. Spin polarization transfer by the radical pair mechanism. J Chem Phys 2015; 143:054101. [DOI: 10.1063/1.4927589] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mehdi Zarea
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Mark A. Ratner
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Michael R. Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| |
Collapse
|
4
|
Yonemura H, Forbes MDE. Electron Spin Exchange in Linked Phenothiazine-Viologen Charge Transfer Complexes Incorporated in "Through-Ring" (Rotaxane) α-Cyclodextrins. Photochem Photobiol 2015; 91:672-7. [PMID: 25682983 DOI: 10.1111/php.12436] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/05/2015] [Indexed: 12/23/2022]
Abstract
A series of covalently bound phenothiazine (PHZ) donor and methylviologen (V) acceptor compounds with polymethylene chain spacers (C8 , C10 , C12 ) were incorporated in a "through-ring" (rotaxane) fashion to α-cyclodextrin (α-CD) hosts such that the alkyl chains were fully extended, with the donor and acceptor on opposite sides of the α-CD cylinder. Photoexcitation of the PHZ unit induces electron transfer from the PHZ first excited triplet state to the V moiety, forming a biradicaloid charge-separated state. Time-resolved electron paramagnetic resonance (TREPR) spectroscopy at the X-band and Q-band microwave frequencies was used to investigate the spin exchange interaction, J, in these biradicaloids. Simulation of the spectra using a "static" model for spin-correlated radical pairs allows extraction of the J values, which are negative in sign and have absolute values range from 2 to 1000 Gauss. Comparison of the PHZn V (n = 8, 10, 12) spectra to those obtained using phenyl ether spacers indicates that π-bonds may assist the electronic coupling. The results are discussed in terms of through-bond vs through-space electronic coupling mechanisms.
Collapse
Affiliation(s)
- Hiroaki Yonemura
- Faculty of Engineering, Department of Applied Chemistry, Kyushu University, Higashi-ku, Fukuoka, Japan
| | | |
Collapse
|
5
|
Zarea M, Carmieli R, Ratner MA, Wasielewski MR. Spin Dynamics of Radical Pairs with Restricted Geometries and Strong Exchange Coupling: The Role of Hyperfine Coupling. J Phys Chem A 2014; 118:4249-55. [DOI: 10.1021/jp5039283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Mehdi Zarea
- Department of Chemistry and Argonne−Northwestern
Solar Energy Research
(ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Raanan Carmieli
- Department of Chemistry and Argonne−Northwestern
Solar Energy Research
(ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Mark A. Ratner
- Department of Chemistry and Argonne−Northwestern
Solar Energy Research
(ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Michael R. Wasielewski
- Department of Chemistry and Argonne−Northwestern
Solar Energy Research
(ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| |
Collapse
|
6
|
Tarasov VF, Jarocha LE, Avdievich NI, Forbes MDE. TREPR spectra of micelle-confined spin correlated radical pairs: I. Molecular motion and simulations. Photochem Photobiol Sci 2014; 13:439-53. [DOI: 10.1039/c3pp50328c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
7
|
Tarasov VF, Jarocha LE, Forbes MDE. TREPR spectra of micelle-confined spin correlated radical pairs: II. Spectral decomposition and asymmetric line shapes. Photochem Photobiol Sci 2014; 13:454-63. [DOI: 10.1039/c3pp50329a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
8
|
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]
|
9
|
Peric M, Bales BL, Peric M. Electron paramagnetic resonance line shifts and line shape changes due to heisenberg spin exchange and dipole-dipole interactions of nitroxide free radicals in liquids 8. Further experimental and theoretical efforts to separate the effects of the two interactions. J Phys Chem A 2012; 116:2855-66. [PMID: 22288424 DOI: 10.1021/jp210057x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The work in part 6 of this series (J. Phys. Chem. A 2009, 113, 4930), addressing the task of separating the effects of Heisenberg spin exchange (HSE) and dipole-dipole interactions (DD) on electron paramagnetic resonance (EPR) spectra of nitroxide spin probes in solution, is extended experimentally and theoretically. Comprehensive measurements of perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDT) in squalane, a viscous alkane, paying special attention to lower temperatures and lower concentrations, were carried out in an attempt to focus on DD, the lesser understood of the two interactions. Theoretically, the analysis has been extended to include the recent comprehensive treatment by Salikhov (Appl. Magn. Reson. 2010, 38, 237). In dilute solutions, both interactions (1) introduce a dispersion component, (2) broaden the lines, and (3) shift the lines. DD introduces a dispersion component proportional to the concentration and of opposite sign to that of HSE. Equations relating the EPR spectral parameters to the rate constants due to HSE and DD have been derived. By employing nonlinear least-squares fitting of theoretical spectra to a simple analytical function and the proposed equations, the contributions of the two interactions to items 1-3 may be quantified and compared with the same parameters obtained by fitting experimental spectra. This comparison supports the theory in its broad predictions; however, at low temperatures, the DD contribution to the experimental dispersion amplitude does not increase linearly with concentration. We are unable to deduce whether this discrepancy is due to inadequate analysis of the experimental data or an incomplete theory. A new key aspect of the more comprehensive theory is that there is enough information in the experimental spectra to find items 1-3 due to both interactions; however, in principle, appeal must be made to a model of molecular diffusion to separate the two. The permanent diffusion model is used to illustrate the separation in this work. In practice, because the effects of DD are dominated by HSE, negligible error is incurred by using the model-independent extreme DD limit of the spectral density functions, which means that DD and HSE may be separated without appealing to a particular model.
Collapse
Affiliation(s)
- Mirna Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, California 91330, USA.
| | | | | |
Collapse
|
10
|
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.
Collapse
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
| | | | | | | | | | | |
Collapse
|
11
|
Sul’timova NB, Levin PP, Chaikovskaya ON. Laser photolysis study of the transient products of 4-carboxybenzophenone-sensitized photolysis of chlorophenoxyacetic acid-based herbicides in aqueous micellar solutions. HIGH ENERGY CHEMISTRY 2010. [DOI: 10.1134/s0018143910050073] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
12
|
Lebedeva NV, Tarasov VF, Resendiz MJE, Garcia-Garibay MA, White RC, Forbes MDE. The Missing Link Between Molecular Triplets and Spin-Polarized Free Radicals: Room Temperature Triplet States of Nanocrystalline Radical Pairs. J Am Chem Soc 2009; 132:82-4. [DOI: 10.1021/ja909521u] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Natalia V. Lebedeva
- Caudill Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599-3290, Semenov Institute of Chemical Physics, Kosygin St. 4, Moscow 119991, Russia, and Department of Chemistry, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095
| | - Valery F. Tarasov
- Caudill Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599-3290, Semenov Institute of Chemical Physics, Kosygin St. 4, Moscow 119991, Russia, and Department of Chemistry, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095
| | - Marino J. E. Resendiz
- Caudill Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599-3290, Semenov Institute of Chemical Physics, Kosygin St. 4, Moscow 119991, Russia, and Department of Chemistry, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095
| | - Miguel A. Garcia-Garibay
- Caudill Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599-3290, Semenov Institute of Chemical Physics, Kosygin St. 4, Moscow 119991, Russia, and Department of Chemistry, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095
| | - Ryan C. White
- Caudill Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599-3290, Semenov Institute of Chemical Physics, Kosygin St. 4, Moscow 119991, Russia, and Department of Chemistry, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095
| | - Malcolm D. E. Forbes
- Caudill Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599-3290, Semenov Institute of Chemical Physics, Kosygin St. 4, Moscow 119991, Russia, and Department of Chemistry, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095
| |
Collapse
|
13
|
Mi Q, Ratner MA, Wasielewski MR. Time-Resolved EPR Spectra of Spin-Correlated Radical Pairs: Spectral and Kinetic Modulation Resulting from Electron−Nuclear Hyperfine Interactions. J Phys Chem A 2009; 114:162-71. [DOI: 10.1021/jp907476q] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qixi Mi
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Mark A. Ratner
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Michael R. Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113
| |
Collapse
|
14
|
Gorelik VR, Tarasov VF, Shakirov SR, Bagryanskaya EG. Effect of nitroxide radicals on chemically induced dynamic electron polarization of spin-correlated radical pairs in aqueous micellar solutions of sodium dodecyl sulfate. Russ Chem Bull 2008. [DOI: 10.1007/s11172-008-0184-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
15
|
Bagryanskaya EG, Sagdeev RZ. Dynamic and stimulated nuclear polarisation in photochemical radical reactions. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc2000v069n11abeh000599] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
16
|
White RC, Gorelik V, Bagryanskaya EG, Forbes MDE. Photoredox chemistry of AOT: electron transfer and hydrogen abstraction in microemulsions involving the surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:4183-91. [PMID: 17343399 DOI: 10.1021/la063322a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Time-resolved magnetic resonance experiments (TREPR and CIDNP) are used to investigate previously unobserved redox chemistry of the surfactant dioctyl sulfosuccinate ester (AOT) using the photoexcited triplet state of anthraquinone 2,6-disulfonate (3AQDS*). Several different free radicals resulting from two independent oxidation pathways (electron transfer and hydrogen abstraction) are observed. These include the radical ions of AQDS and sulfite from electron-transfer processes, carbon-centered radicals from H-atom abstraction reactions, and an additional carbon-centered radical formed by electron transfer from the AOT sulfonate head group followed by the loss of SO3. The radicals exhibit intense chemically induced dynamic electron spin polarization (CIDEP) in their TREPR spectra. The intensity ratios of the observed TREPR signals for each radical depend on the water pool size and temperature, which in turn affect the predominant CIDEP mechanism. All signal carriers are accounted for by simulation, and CIDNP results provide strong supporting evidence for the assignments.
Collapse
Affiliation(s)
- Ryan C White
- Caudill Laboratories, CB#3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | | | | | | |
Collapse
|
17
|
Vasserman AM, Zakharova YA, Otdel’nova MV, Aliev II, Motyakin MV. The effect of organic additives on the local dynamics of polyelectrolyte-surfactant complexes. COLLOID JOURNAL 2006. [DOI: 10.1134/s1061933x06060020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
18
|
Tarasov VF, White RC, Forbes MDE. Photo-oxidation of diglycine in confined media Relaxation of longitudinal magnetization in spin correlated radical pairs. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2006; 63:776-83. [PMID: 16458046 DOI: 10.1016/j.saa.2005.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Revised: 09/23/2005] [Accepted: 10/01/2005] [Indexed: 05/06/2023]
Abstract
Time-resolved electron paramagnetic resonance spectra (X-band) of correlated radical pairs created in AOT reverse micelles are presented and simulated using the microreactor model. They are discussed in terms of the two-site model with a particular emphasis on longitudinal relaxation mechanisms. The geminate radical pair is created by photo-oxidation of dyglicine by the excited triplet states of an anthraquinone salt. The strong chemically induced electron spin polarization observed is due to three mechanisms: TM, RPM, and SCRPM. Relative contributions from these mechanisms depend on the water pool volume and the time of observation. There are three types of longitudinal relaxation in radical pairs. The first is relaxation of the RPM induced longitudinal magnetization in spin correlated radical pairs. The second is the longitudinal relaxation in radical pairs which are not correlated (with a zero value of the double quantum coherence). In such pairs, the generation of longitudinal magnetization due to RPM is impossible, and the spin-selective recombination of the pairs is ineffective. Under all experimental conditions, the first type of relaxation is slower than the second type. For both, the physical mechanism leading to relaxation is modulation of the Heisenberg electron spin exchange interaction. This is an internal relaxation process. The third relaxation type occurs in radical pairs due to ordinary longitudinal relaxation in non-interacting radicals. Normally, relaxation of the third type is the slowest of the three. This explains time and micelle size dependence of the relative contribution of RPM into TREPR spectra. It seems reasonable to suggest that the creation of the initial spin state populations is partially adiabatic.
Collapse
Affiliation(s)
- Valery F Tarasov
- Semenov Institute of Chemical Physics RAS, Moscow 199999, Russia
| | | | | |
Collapse
|
19
|
Forbes MDE, Dukes KE, Avdievich NI, Harbron EJ, DeSimone JM. Flexible Biradicals in Liquid and Supercritical Carbon Dioxide: The Exchange Interaction, the Chain Dynamics, and a Comparison with Conventional Solvents. J Phys Chem A 2006; 110:1767-74. [PMID: 16451006 DOI: 10.1021/jp053183q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
X-band time-resolved electron paramagnetic resonance (TREPR) spectra of three flexible biradicals of varying chain length and structure were obtained in liquid and supercritical carbon dioxide (CO2) solutions and compared to conventional solvents. For C16 acyl-alkyl biradical 1a, an average spin exchange interaction between the radical centers, J(avg), was obtained by spectral simulation using a simple model for spin-correlated radical pairs (SCRPs) and a small amount of T2 relaxation from a previously established J modulation mechanism. A large solvent effect on J(avg) was observed for the first time, varying by almost 1 order of magnitude from CO2 (J(avg) = -120 +/- 10 MHz) to heavy mineral oil (-11 +/- 3 MHz) for 1a. For C15 bis(alkyl) biradical 1b, spectra obtained under supercritical conditions are only slightly different from those detected in liquid CO2 but differ from spectra taken in benzene. For C10 acyl-alkyl biradical 2a, more emissive spin polarization due to S-T- mixing is observed in CO2 than in benzene. These results are discussed in terms of solvent properties such as dielectric constant, viscosity, and specific interactions. Both chain dynamics and changes to the equilibrium distribution of end-to-end distances can alter J(avg) and the observed ratio of S-T0 to S-T- mixing; however, faster chain dynamics is concluded to be the most likely cause of the observed effects in these systems.
Collapse
Affiliation(s)
- Malcolm D E Forbes
- Department of Chemistry, CB No. 3290, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
| | | | | | | | | |
Collapse
|
20
|
Levin PP, Sul'timova NB, Chaikovskaya ON. Kinetics of fast reactions of triplet states and radicals under photolysis of 4,4′-dimethylbenzophenone in the presence of 4-halophenols in micellar solutions of sodium dodecyl sulfate in magnetic field. Russ Chem Bull 2005. [DOI: 10.1007/s11172-005-0423-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
21
|
Modeling of recombination kinetics of radical pairs in magnetic field. Comparison with experimental dependences on the frequency of encounters in biradicals. Russ Chem Bull 2005. [DOI: 10.1007/s11172-005-0370-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
22
|
White RC, Tarasov VF, Forbes MDE. Photooxidation of diglycine in confined media. Application of the microreactor model for spin-correlated radical pairs in reverse micelles and water-in-oil microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2721-2727. [PMID: 15779940 DOI: 10.1021/la047382x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Time-resolved electron paramagnetic resonance spectra (X-band) of correlated radical pairs created in AOT reverse micelles and microemulsions are presented, simulated, and discussed using the microreactor model. The radicals are formed inside the water pool using photooxidation of diglycine by the excited triplet states of two different anthraquinone sulfonate salts. Water pool size and temperature effects on the spectra are reported, and the simulations allow for extraction of the diffusion coefficient in the interior, which monotonically increases with water pool size. The data directly correlate with the diffusional properties of correlated radical pairs in regular aqueous micelle solutions studied previously by similar methods. Competition between H-atom abstraction and electron transfer is observed with anthraquinone sulfonate, but electron transfer is the only reaction pathway observed when anthraquinone disulfonate triplet state is the sensitizing species.
Collapse
Affiliation(s)
- Ryan C White
- Venable and Kenan Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | | | | |
Collapse
|
23
|
Chaney EE, Forbes MDE. Dynamics of Spin-Correlated Radical Pairs in Non-Ionic Surfactant Solutions. J Phys Chem B 2003. [DOI: 10.1021/jp026601p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Erin E. Chaney
- Venable and Kenan Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Malcolm D. E. Forbes
- Venable and Kenan Laboratories, Department of Chemistry, CB #3290, University of North Carolina, Chapel Hill, North Carolina 27599
| |
Collapse
|
24
|
Tarasov VF, Chemerisov SD, Trifunac AD. H-Atom Electron-Spin Polarization in Irradiated Water and Ice Confined in the Nanopores of Vycor Glass. J Phys Chem B 2003. [DOI: 10.1021/jp021438j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Valery F. Tarasov
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | | | | |
Collapse
|
25
|
Tsentalovich YP, Forbes MDE, Morozova OB, Plotnikov IA, McCaffrey VP, Yurkovskaya AV. Spin and Molecular Dynamics in Acyl-Containing Biradicals: Time-Resolved Electron Paramagnetic Resonance and Laser Flash Photolysis Study. J Phys Chem A 2002. [DOI: 10.1021/jp020098z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuri P. Tsentalovich
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, and Venable and Kenan Laboratories, Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Malcolm D. E. Forbes
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, and Venable and Kenan Laboratories, Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Olga B. Morozova
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, and Venable and Kenan Laboratories, Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Igor A. Plotnikov
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, and Venable and Kenan Laboratories, Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Vanessa P. McCaffrey
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, and Venable and Kenan Laboratories, Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Alexandra V. Yurkovskaya
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, and Venable and Kenan Laboratories, Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599
| |
Collapse
|
26
|
TSENTALOVICH YURIP, FORBES MALCOLMDE. Spin relaxation in acyl radicals measured using spin correlated radical pair (SCRP) polarization in flexible biradicals. Mol Phys 2002. [DOI: 10.1080/00268970110112354] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
27
|
Akiyama K, Tero-Kubota S. One- and Two-Dimensional EPR Studies on the Radical Pair Generated by the Photoreduction of 9,10-Anthraquinone-1,5-disulfonate in Aerosol OT Reverse Micelles. J Phys Chem B 2002. [DOI: 10.1021/jp0155157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kimio Akiyama
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Shozo Tero-Kubota
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| |
Collapse
|
28
|
Dubinski AA, Perekhodtsev GD, Poluektov OG, Rajh T, Thurnauer MC. Analytical Treatment of EPR Spectra of Weakly Coupled Spin-Correlated Radical Pairs in Disordered Solids: Application to the Charge-Separated State in TiO2 Nanoparticles. J Phys Chem B 2002. [DOI: 10.1021/jp013276h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
29
|
Lebedeva NV, Bagryanskaya EG, Gorelik VR, Koptyug IV, Sagdeev RZ. Temperature and Salt Addition Effect on the Micellized Radical Pairs Recombination Studied by Stimulated Nuclear Polarization. J Phys Chem A 2001. [DOI: 10.1021/jp004481k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N. V. Lebedeva
- International Tomography Center, SB RAS, Novosibirsk, Russia
| | | | - V. R. Gorelik
- International Tomography Center, SB RAS, Novosibirsk, Russia
| | - I. V. Koptyug
- International Tomography Center, SB RAS, Novosibirsk, Russia
| | - R. Z. Sagdeev
- International Tomography Center, SB RAS, Novosibirsk, Russia
| |
Collapse
|