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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]
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Shushin AI. Effect of state-selective reactive decay on the evolution of quantum systems. J Chem Phys 2010; 133:044505. [DOI: 10.1063/1.3461133] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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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.
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Affiliation(s)
- Valery F Tarasov
- Semenov Institute of Chemical Physics RAS, Moscow 199999, Russia
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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.
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Affiliation(s)
- Malcolm D E Forbes
- Department of Chemistry, CB No. 3290, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Spin-chemical approach to photochemistry: reaction control by spin quantum operation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2003. [DOI: 10.1016/s1389-5567(02)00038-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Shushin AI. The Green’s function for multistate Schrödinger-type equation. Magnetic-field effects in radical pair recombination in the presence of interaction potential. J Chem Phys 2002. [DOI: 10.1063/1.1475762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Neufeld AA, Doktorov AB, Pedersen JB. Green’s function calculation of electron spin polarization. V. Quasi-equilibrium and fast mixing approximations for micellar radical pairs. J Chem Phys 2001. [DOI: 10.1063/1.1385556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Batchelor SN, Shushin AI. Time-Resolved EPR Study of Reactive Radical Motion in Cotton: Effects of Confinement. J Phys Chem B 2001. [DOI: 10.1021/jp003383w] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S. N. Batchelor
- Unilever Research Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, Great Britain
| | - A. I. Shushin
- Institute of Chemical Physics, Academy of Sciences, Institute of Chemical Physics, Academy of Sciences, 117977, GSP-1, Kosygin str. 4, Moscow, Russia
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Barzykin AV, Seki K, Tachiya M. Kinetics of diffusion-assisted reactions in microheterogeneous systems. Adv Colloid Interface Sci 2001; 89-90:47-140. [PMID: 11215811 DOI: 10.1016/s0001-8686(00)00053-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
This review is focused on the basic theory of diffusion-assisted reactions in microheterogeneous systems, from porous solids to self-organized colloids and biomolecules. Rich kinetic behaviors observed experimentally are explained in a unified fashion using simple concepts of competing distance and time scales of the reaction and the embedding structure. We mainly consider pseudo-first-order reactions, such as luminescence quenching, described by the Smoluchowski type of equation for the reactant pair distribution function with a sink term defined by the reaction mechanism. Microheterogeneity can affect the microscopic rate constant. It also enters the evolution equation through various spatial constraints leading to complicated boundary conditions and, possibly, to the reduction of dimensionality of the diffusion space. The reaction coordinate and diffusive motion along this coordinate are understood in a general way, depending on the problem at hand. Thus, the evolution operator can describe translational and rotational diffusion of molecules in a usual sense, it can be a discrete random walk operator when dealing with hopping of adsorbates in solids, or it can correspond to conformational fluctuations in proteins. Mathematical formulation is universal but physical consequences can be different. Understanding the principal features of reaction kinetics in microheterogeneous systems enables one to extract important structural and dynamical information about the host environments by analyzing suitably designed experiments, it helps building effective strategies for computer simulations, and ultimately opens possibilities for designing systems with controllable reactivity properties.
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Affiliation(s)
- A V Barzykin
- National Institute of Materials and Chemical Research, Tsukuba, Ibaraki, Japan.
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Tarasov VF, Forbes MD. Time resolved electron spin resonance of spin correlated micelle confined radical pairs: shape of the anti-phase structure. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000; 56A:245-263. [PMID: 10727143 DOI: 10.1016/s1386-1425(99)00236-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A new approach to the theory of the EPR of spin correlated radical pairs (SCRP) is formulated. It is based on spectral exchange methods as applied to the two-site model and takes into account explicitly both the motion of one quantum (transverse magnetization) and two quantum coherences (polarizations) of SCRPs. This innovation allows for the interpretation of anti phase structure (APS) spectral shape asymmetry and for the transformation of the initially created ST0RPM polarization into the APS spectral pattern. The results of this method as applied to micellized spin correlated radical pairs have been compared with the exact numerical solution of the corresponding stochastic Liouville equation and is commented on.
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Affiliation(s)
- V F Tarasov
- Institute of Chemical Physics of the Russian Academy of Sciences, Moscow
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Fukuju T, Yashiro H, Maeda K, Murai H. Real-time observation of the singlet–triplet dephasing effect on the spin dynamics of the spin-correlated radical pair formed in the photolysis of tetraphenylhydrazine in a micelle. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00320-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Time-resolved ESR in a spin-correlated radical pair with large hyperfine coupling constant at 31P. Micellar size effects and the role of flip-flop transitions. Chem Phys 1998. [DOI: 10.1016/s0301-0104(97)00330-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Manifestation of spin exchange relaxation in microwave field induced magnetic field effects on recombination of confined radical pairs. Chem Phys Lett 1998. [DOI: 10.1016/s0009-2614(97)01268-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fukuju T, Yashiro H, Maeda K, Murai H, Azumi T. Singlet-Born SCRP Observed in the Photolysis of Tetraphenylhydrazine in an SDS Micelle: Time Dependence of the Population of the Spin States. J Phys Chem A 1997. [DOI: 10.1021/jp971620y] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tadahiro Fukuju
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
| | - Haruhiko Yashiro
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
| | - Kiminori Maeda
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
| | - Hisao Murai
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
| | - Tohru Azumi
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
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Pedersen JB, Jørgensen JS. High-Field Supercage Model for Radical Pair Reactions in Micelles. J Phys Chem A 1997. [DOI: 10.1021/jp962011d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Tarasov V, Yashiro H, Maeda K, Azumi T, Shkrob I. Spin-correlated radical pairs in micellar systems: mechanism of CIDEP and the micelle size dependence. Chem Phys 1996. [DOI: 10.1016/s0301-0104(96)00145-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Forbes MDE, Schulz GR, Avdievich NI. Unusual Dynamics of Micellized Radical Pairs Generated from Photochemically Active Amphiphiles. J Am Chem Soc 1996. [DOI: 10.1021/ja960102i] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Malcolm D. E. Forbes
- Venable and Kenan Laboratories Department of Chemistry, CB No. 3290 University of North Carolina Chapel Hill, North Carolina 27599
| | - Gregory R. Schulz
- Venable and Kenan Laboratories Department of Chemistry, CB No. 3290 University of North Carolina Chapel Hill, North Carolina 27599
| | - Nikolai I. Avdievich
- Venable and Kenan Laboratories Department of Chemistry, CB No. 3290 University of North Carolina Chapel Hill, North Carolina 27599
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The ST_-relaxation mechanism of magnetic field effects on radical pair recombination. Intraradical relaxation versus ST_-relaxation transitions. Chem Phys Lett 1996. [DOI: 10.1016/0009-2614(96)00834-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Forbes MDE, Avdievich NI, Ball JD, Schulz GR. Chain Dynamics Cause the Disappearance of Spin-Correlated Radical Pair Polarization in Flexible Biradicals. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960245r] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Malcolm D. E. Forbes
- Venable and Kenan Laboratories, Department of Chemistry, CB 3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Nikolai I. Avdievich
- Venable and Kenan Laboratories, Department of Chemistry, CB 3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Jonathan D. Ball
- Venable and Kenan Laboratories, Department of Chemistry, CB 3290, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Gregory R. Schulz
- Venable and Kenan Laboratories, Department of Chemistry, CB 3290, University of North Carolina, Chapel Hill, North Carolina 27599
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Avdievich NI, Forbes MDE. Strong Modulation of the Exchange Interaction in a Spin-Polarized, Aryl Ether-Linked 1,14-Biradical. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp9531422] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nikolai I. Avdievich
- 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
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Shushin A. On the antiphase structure of the ESR spectra of spin-correlated radical pairs. Dependence on dimensionality. Chem Phys Lett 1995. [DOI: 10.1016/0009-2614(95)00994-f] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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