Analysis of Polarized Epr Spectra

Hore, P. J.

doi:10.1016/b978-0-444-88050-5.50017-3

Cited by 79 publications

(99 citation statements)

References 63 publications

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“…Provided subsequent forward electron transfer is blocked, the recombination of the primary radical pair responds to magnetic fields in excess of Ϸ1 mT. In unblocked reaction centers, spin correlation can be transferred along the electron transport chain from the primary to the secondary radical pair (34)(35)(36), whose lifetime is also magnetically sensitive (37)(38)(39). Similar effects occur in plant photosystems.…”

mentioning

confidence: 61%

Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

483

449

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Migratory birds travel vast distances each year, finding their way by various means, including a remarkable ability to perceive the Earth's magnetic field. Although it has been known for 40 years that birds possess a magnetic compass, avian magnetoreception is poorly understood at all levels from the primary biophysical detection events, signal transduction pathways and neurophysiology, to the processing of information in the brain. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. Here, we present a physical chemist's perspective on the ''radical pair mechanism'' of compass magnetoreception in birds. We outline the essential chemical requirements for detecting the direction of an Earth-strength Ϸ50 T magnetic field and comment on the likelihood that these might be satisfied in a biologically plausible receptor. Our survey concludes with a discussion of cryptochrome, the photoactive protein that has been put forward as the magnetoreceptor molecule.

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mentioning

confidence: 61%

Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

483

449

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“…On the other hand, for a strongly coupled TRP the RP phase should remain unchanged at L ‖ B and L ⊥ B orientations, which is the case. 25 Therefore, we assign the observed narrow signal to the TRP, which is formed as a result of photoexcited ET in H 2 P-Cu(I)(phen) 2 -C 60 rotaxane.…”

Section: Resultsmentioning

confidence: 88%

Photoexcited State Properties of H₂-Porphyrin/C₆₀-Based Rotaxanes as Studied by Time-Resolved Electron Paramagnetic Resonance Spectroscopy

et al. 2011

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Light-driven intramolecular electron transfer (ET) and energy transfer (EnT) processes in two rotaxanes, the first containing two free base porphyrins and C60 fullerene moieties incorporated around a Cu(I)bisphenanthroline core ((H2P)2-Cu(I)(phen)2-C60) and a second rotaxane lacking the fullerene moiety ((H2P)2-Cu(I)(phen)2) were studied by X-band (9.5 GHz) time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The experiments were performed in a frozen toluene and ethanol, and different phases of the nematic liquid crystal (E-7). It is demonstrated that the ET and EnT processes in the (H2P)2-Cu(I)(phen)2-C60 rotaxane in different media result in formation of the same charge separated state, namely (H2P)2•+-Cu(I)(phen)2•−-C60, while photoexcitation of the (H2P)2-Cu(I)(phen)2 rotaxane does not induce noticeable transfer processes in these matrices. The results are discussed in terms of the high conformational mobility of the rotaxanes, which enables changes in the molecular topography and resultant modification of the rates and routes of photoinduced processes occurring in these systems. The parameters of the transfer processes are compared with those obtained in our previous study of (ZnP)2-Cu(I)(phen)2-C60 and (ZnP)2-Cu(I)(phen) rotaxanes under the same experimental conditions.

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“…19,22,32 In the following calculations, the system is approximated by a pair of spin-spin coupled electrons A and B (representing A 1 -and P 700 + , respectively) and a spin-1 / 2 nucleus, N, which is coupled via an axial hyperfine interaction a to electron A. The electronic spin-spin coupling consists of a traceless axial dipolar tensor D with z-component D zz and isotropic exchange interaction J.…”

Section: Theory 321 Model For Endor On Radical Pairsmentioning

confidence: 99%

Pulsed ENDOR Studies of Short-Lived Spin-Correlated Radical Pairs in Photosynthetic Reaction Centers

2002

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Time-resolved electron-nuclear double resonance (TR-ENDOR) performed on the spin-correlated radical pair P 700 + A 1 -in frozen solution samples of PSI shows a superposition of the ENDOR lines expected for the individual radicals P 700 + and A 1 -. Presented here are TR-ENDOR spectra taken over a range of EPR field positions. The spectra are unusual because they show both absorptive and emissive contributions and a strong dependence on the field. The nature of the spectra is explored using the theory of spin-correlated radical pairs. It is found that the electron spin polarization in the radical pair is responsible for the absorptive/ emissive nature of the TR-ENDOR spectra and that the mixed electronic eigenstates give rise to transitions in addition to those usually found in ENDOR. Computer simulations based on a model containing two coupled electrons and a single spin-1 / 2 nucleus are able to reproduce the spectra and their field dependence. It is also shown that TR-ENDOR spectra from a spin-correlated radical pair are sensitive to the relative signs of the hyperfine couplings.

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Analysis of Polarized Epr Spectra

Cited by 79 publications

References 63 publications

Chemical magnetoreception in birds: The radical pair mechanism

Chemical magnetoreception in birds: The radical pair mechanism

Photoexcited State Properties of H₂-Porphyrin/C₆₀-Based Rotaxanes as Studied by Time-Resolved Electron Paramagnetic Resonance Spectroscopy

Pulsed ENDOR Studies of Short-Lived Spin-Correlated Radical Pairs in Photosynthetic Reaction Centers

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Analysis of Polarized Epr Spectra

Cited by 79 publications

References 63 publications

Chemical magnetoreception in birds: The radical pair mechanism

Chemical magnetoreception in birds: The radical pair mechanism

Photoexcited State Properties of H2-Porphyrin/C60-Based Rotaxanes as Studied by Time-Resolved Electron Paramagnetic Resonance Spectroscopy

Pulsed ENDOR Studies of Short-Lived Spin-Correlated Radical Pairs in Photosynthetic Reaction Centers

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Photoexcited State Properties of H₂-Porphyrin/C₆₀-Based Rotaxanes as Studied by Time-Resolved Electron Paramagnetic Resonance Spectroscopy