Intersystem Crossing versus Electron Transfer in Porphyrin-Based Donor−Bridge−Acceptor Systems: Influence of a Paramagnetic Species
Abstract
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.
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.Attached Files
Supplemental Material - ja0370488si20030703_095608.pdf
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Additional details
- Eprint ID
- 77480
- Resolver ID
- CaltechAUTHORS:20170516-072218088
- Swedish Research Council
- Hasselblad Foundation
- Knut and Alice Wallenberg Foundation
- Created
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2017-05-16Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field