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Intersystem Crossing versus Electron Transfer in Porphyrin-Based Donor−Bridge−Acceptor Systems: Influence of a Paramagnetic Species

Pettersson, Karin and Kilså, Kristine and Mårtensson, Jerker and Albinsson, Bo (2004) Intersystem Crossing versus Electron Transfer in Porphyrin-Based Donor−Bridge−Acceptor Systems: Influence of a Paramagnetic Species. Journal of the American Chemical Society, 126 (21). pp. 6710-6719. ISSN 0002-7863. doi:10.1021/ja0370488.

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We have investigated how the spin state of an acceptor influences the photophysical processes in a donor−bridge−acceptor (D−B−A) system. The system of choice has zinc porphyrin as the electron donor and high- or low-spin iron(III) porphyrin as the acceptor. The spin state of the acceptor porphyrin is switched simply by coordinating imidazole ligands to the metal center. The D−A center−center distance is 26 Å, and the bridging chromophore varies from π-conjugated to a σ-bonded system. The presence of a high-spin iron(III) porphyrin in such systems has previously been shown to significantly enhance intersystem crossing in the remote zinc porphyrin donor, whereas no significant electron transfer to the iron porphyrin acceptor was observed, even though the thermodynamics would allow for photoinduced electron transfer. Here, we demonstrate that by switching the acceptor to a low-spin state, the dominating photophysical process is drastically changed; the low-spin system shows long-range electron transfer on the picosecond time-scale, and intersystem crossing occurs at its “normal” rate.

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Additional Information:© 2004 American Chemical Society. Received 3 July 2003. Published online 11 May 2004. Published in print 1 June 2004. This work was supported by grants from the Swedish Research Council, the Knut and Alice Wallenberg Foundation, and the Hasselblad Foundation. We thank Dr. Angel J. Di Bilio for skillful assistance with recording of the EPR spectra.
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Swedish Research CouncilUNSPECIFIED
Hasselblad FoundationUNSPECIFIED
Knut and Alice Wallenberg FoundationUNSPECIFIED
Issue or Number:21
Record Number:CaltechAUTHORS:20170516-072218088
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Official Citation:Intersystem Crossing versus Electron Transfer in Porphyrin-Based Donor−Bridge−Acceptor Systems:  Influence of a Paramagnetic Species Karin Pettersson, Kristine Kilså, Jerker Mårtensson, and Bo Albinsson Journal of the American Chemical Society 2004 126 (21), 6710-6719 DOI: 10.1021/ja0370488
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77480
Deposited By: Ruth Sustaita
Deposited On:16 May 2017 19:36
Last Modified:15 Nov 2021 17:31

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