Magnetic field effects on the catalytic oxidation of 2,6-di-tert-butylphenol by CoSMDPT:  Deuterium and oxygen-17 magnetic isotope effects

Perito, Richard P.; Corden, Barry B.

doi:10.1021/ja00219a022

Cited by 10 publications

(4 citation statements)

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“…At higher fields, the rate of product formation decreases and goes below the control rate at 7 T. A radical pair mechanism is proposed in which the magnetic field-dependent (partially) rate-determining step is regeneration of the active Co(II) catalyst and production of the phenolic radical in a spin-correlated step (Figure 6). 74 This is a landmark result in magnetic field effect studies of catalytic reactions. The reaction has only one product, so a distinct singlet and triplet reaction product manifold does not exist.…”

Section: K Radical Pair Recombination In Biological Systemsmentioning

confidence: 94%

“…Magnetic Field Effects in Catalytic Reactions A remarkable magnetic field dependence has been observed for the cobalt and manganese catalyzed oxidation of 2,6-di-tert-butylphenol (Figure 5). 73, 74 The rate of quinone product formation exhibits a biphasic increase to a maximum 50% enhancement at 100 mT (relative to the control rate at 0 T). At higher fields, the rate of product formation decreases and goes below the control rate at 7 T. A radical pair mechanism is proposed in which the magnetic field-dependent (partially) rate-determining step is regeneration of the active Co(II) catalyst and production of the phenolic radical in a spin-correlated step (Figure 6).…”

Section: K Radical Pair Recombination In Biological Systemsmentioning

confidence: 99%

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Magnetic Field Effects in Biology: A Survey of Possible Mechanisms with Emphasis on Radical-Pair Recombination

Grissom¹

1995

Chem. Rev.

379

272

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Section: K Radical Pair Recombination In Biological Systemsmentioning

confidence: 94%

Section: K Radical Pair Recombination In Biological Systemsmentioning

confidence: 99%

Magnetic Field Effects in Biology: A Survey of Possible Mechanisms with Emphasis on Radical-Pair Recombination

Grissom¹

1995

Chem. Rev.

379

272

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“…In contrast, other biological effects are well documented [Anderson, 1993]. For example, magnetic ®elds are known to increase mRNA transcription [Goodman et al, 1993], alter the ion potential of plasma membranes [Luben, 1991], change intracellular concentrations of cyclic adenosine monophosphate [Schimmelpfeng et al, 1995], change the rates of chemical reactions [Perito and Corden, 1988], and change hormone levels [Kato et al, 1993;Reiter, 1995]. Because these cellular processes contribute to normal cell behavior and interactions, magnetic ®elds have the potential of disrupting development.…”

Section: Introductionmentioning

confidence: 99%

Growth and developmental stability ofDrosophila melanogaster in low frequency magnetic fields

Graham

Fletcher

Tigue

et al. 2000

Bioelectromagnetics

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Magnetic fields (60 Hz) of 1.5 and 80 microT caused a significant reduction in the weight of Drosophila melanogaster. Moreover, fruit flies in an 80 microT field showed lower developmental stability than either those in a 0 or 1.5 microT field. Developmental instability was measured by fluctuating asymmetry and frequency of phenodeviants. More of the flies in the 80 microT field had fused abdominal segments, and they were more asymmetrical for wing vein R(4+5). The flies in the 1.5 microT field actually showed greater developmental stability than the control flies. Fewer of them had fused abdominal segments, and they were more symmetrical for wing vein R(4+5). Thus, at low field strengths, flies are more developmentally stable than control flies, even though they weigh less.

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“…Magnetic field effects on the photophysics and photochemistry of metal complexes (29.30) and on the outer sphere electron transfer reactions involving metal complexes (31,32) show that weak magnetic fields ( < I T) can perturb only the spin multiplicity of the RP, whereas strong magnetic fields (> 1 T) can also affect the electronic energy levels of the polyatomic molecules. Corden and coworkers (33,34) identified the RP containing Co" as being responsible for the observed magnetic field effects on the catalytic oxidation of 2,6-disubstituted phenols and discussed the role of electron spin angular momentum by examining both low spin and high spin cobalt(I1) complexes as catalysts.…”

Section: Introductionmentioning

confidence: 99%

The Origin of Magnetic Field Dependent Recombination in Alkylcobalamin Radical Pairs

Natarajan

Grissom

1996

Photochem & Photobiology

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Magnetic field effect studies of alkylcobalamin photolysis provide evidence for the formation of a reactive radical pair that is born in the singlet spin state. The radical pair recombination process that is responsible for the magnetic field dependence of the continuous-wave (CW) quantum yield is limited to the diffusive radical pair. Although the geminate radical pair of adenosylcob(III)alamin also undergoes magnetic field dependent recombination (A.M. Chagovetz and C. B. Grissom, J. Am. Chem. soc. 115, 12152-12157, 1993), this process does not account for the magnetic field dependence of the CW quantum yield that is only observed in viscous solvents. Glycerol and ethylene glycol increase the microviscosity of the solution and thereby increase the lifetime of the spin-correlated diffusive radical pair. This enables magnetic field dependent recombination among spin-correlated diffusive radical pairs in the solvent cage. Magnetic field dependent recombination is not observed in the presence of nonviscosigenic alcohols such as isopropanol, thereby indicating the importance of the increased microviscosity of the medium. Paramagnetic radical scavengers that trap alkyl radicals that escape the solvent cage do not diminish the magnetic field effect on the CW quantum yield, thereby ruling out radical pair recombination among randomly diffusing radical pairs, as well as excluding the involvement of solvent-derived radicals. Magnetic field dependent recombination among alkylcobalamin radical pairs has been simulated by a semi-classical model of radical pair dynamics and recombination. These calculations support the existence of a singlet radical pair precursor.

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Magnetic field effects on the catalytic oxidation of 2,6-di-tert-butylphenol by CoSMDPT: Deuterium and oxygen-17 magnetic isotope effects

Cited by 10 publications

References 0 publications

Magnetic Field Effects in Biology: A Survey of Possible Mechanisms with Emphasis on Radical-Pair Recombination

Magnetic Field Effects in Biology: A Survey of Possible Mechanisms with Emphasis on Radical-Pair Recombination

Growth and developmental stability ofDrosophila melanogaster in low frequency magnetic fields

The Origin of Magnetic Field Dependent Recombination in Alkylcobalamin Radical Pairs

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