Origin of the S* excited state feature of carotenoids in light-harvesting complex 1 from purple photosynthetic bacteria

Niedzwiedzki, Dariusz M., Swainsbury, David J.K., Martin, Elizabeth C., Hunter, C. Neil and Blankenship, Robert E. (2017) Origin of the S* excited state feature of carotenoids in light-harvesting complex 1 from purple photosynthetic bacteria. Journal of Physical Chemistry B, 121 (32). pp. 7571-7585. ISSN 1520-6106

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Abstract

This spectroscopic study investigates the origin of the transient feature of the S* excited state of carotenoids bound in LH1 complexes from purple bacteria. The studies were performed on two RC-LH1 complexes from Rba. sphaeroides strains that bound carotenoids with different carbon−carbon double bond conjugation N, neurosporene (N = 9) and spirilloxanthin (N = 13). The S* transient spectral feature, originally associated with an elusive and optically silent excited state of spirilloxanthin in the LH1 complex, may be successfully explained and mimicked without involving any unknown electronic state. The spectral and temporal characteristics of the S* feature suggest that it is associated with triplet−triplet annihilation of carotenoid triplets formed after direct excitation of the molecule via a singlet fission mechanism. Depending on pigment homogeneity and carotenoid assembly in the LH1 complex, the spectro-temporal component associated with triplet−triplet annihilation may simply resolve a pure T-S spectrum of a carotenoid. In some cases (like spirilloxanthin), the T-S feature will also be accompanied by a carotenoid Stark spectrum and/or residual transient absorption of minor carotenoid species bound into LH1 antenna complex.

Item Type: Article
Additional Information: Funding Information: Spectroscopic studies were supported by the Photosynthetic Antenna Research Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC 0001035. D.J.K.S., E.C.M., and C.N.H. were supported by a grant from the Biotechnology and Biological Sciences Research Council, UK (BB/M000265/1). C.N.H. acknowledges support from the European Research Council (Advanced Award 338895). Publisher Copyright: © 2017 American Chemical Society.
Uncontrolled Keywords: physical and theoretical chemistry,surfaces, coatings and films,materials chemistry ,/dk/atira/pure/subjectarea/asjc/1600/1606
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 17 Aug 2022 12:31
Last Modified: 01 Oct 2022 07:42
URI: https://ueaeprints.uea.ac.uk/id/eprint/87365
DOI: 10.1021/acs.jpcb.7b04251

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