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Photochemistry of a butylene linked porphyrin quinone donor-acceptor system studied by time-resolved and steady-state EPR spectroscopy

Kay, CWM; Kurreck, H; Batchelor, SN; Tian, P; Schlupmann, J; Mobius, K; (1995) Photochemistry of a butylene linked porphyrin quinone donor-acceptor system studied by time-resolved and steady-state EPR spectroscopy. APPL MAGN RESON , 9 (4) 459 - 480.

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Abstract

Radicals generated photochemically from a covalently linked porphyrin-quinone donor-acceptor system dissolved in reversed micelles and isotropic solution have been studied by steady-state and time-resolved EPR spectroscopy. In these systems photoinduced intramolecular as well as intermolecular electron transfer processes occur which result in the formation of semiquinone radical anions and porphyrin radical cations. Disproportionation of the semiquinone leads to the formation of porphyrin-hydroquinone (and porphyrin-quinone). The porphyrin-hydroquinone is itself photoactive and reacts through the photoexcited triplet state of the porphyrin. Reduction of the porphyrin to the dihydro form - probably via hydrogen abstraction by the photoexcited porphyrin from the hydroquinone - appears to be the dominant reaction. Once formed the dihydroporphyrin undergoes further similar photochemistry. Emissively polarized spectra are observed from these systems in steady-state EPR experiments. Time-resolved EPR indicates that this polarization is essentially due to the radical tripler pair mechanism.

Type: Article
Title: Photochemistry of a butylene linked porphyrin quinone donor-acceptor system studied by time-resolved and steady-state EPR spectroscopy
Keywords: DYNAMIC ELECTRON POLARIZATION, TRIPLET PAIR MECHANISM, SPIN-RESONANCE, FREE-RADICALS, PARAMAGNETIC-RESONANCE, MODEL SYSTEMS, CYTOCHROME-C, CIDEP, PHOTOSYNTHESIS, EXCHANGE
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: http://discovery.ucl.ac.uk/id/eprint/71635
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