Singlet fission mediates carotenoid-to-bacteriochlorophyll energy transfer in purple photosynthetic bacteria

Abstract

Photosynthesis, the foundation of most life, begins when sunlight is captured by (bacterio)chlorophyll ((B)Chl) and carotenoid (Crt) pigments. These molecules are arranged so that captured energy migrates rapidly to reaction centres, where it is stored as a charge separation. The complementary absorption of Crt and (B)Chl pigments, and rapid energy transfer between them, underpins solar harvesting. Here we report a Crt-to-BChl energy transfer mechanism mediated by singlet fission, in which a high-energy singlet exciton (with spin quantum number S = 0) is converted into two low-energy triplet (S = 1) excitons. In purple photosynthetic bacteria, the Crt S2 singlet exciton splits into Crt and BChl triplet excitons on adjacent sites. Once formed, the triplets transfer cooperatively to BChl and onwards to reaction centres. Energy is transferred from a singlet Crt state, via the spin-protected long-lived triplet pair, to a singlet BChl state. Thus, this singlet fission-mediated mechanism augments solar energy harvesting for photosynthesis.

Metadata

Item Type:	Article
Authors/Creators:	Wang, S. https://orcid.org/0000-0002-1671-218X Sutherland, G.A. https://orcid.org/0000-0002-6319-4637 Pidgeon, J.P. https://orcid.org/0000-0002-1509-5343 Šmitran, M. https://orcid.org/0009-0005-7824-9628 Swainsbury, D.J.K. https://orcid.org/0000-0002-0754-0363 Martin, E.C. Vasilev, C. Hitchcock, A. https://orcid.org/0000-0001-6572-434X Gillard, D.J. https://orcid.org/0000-0002-0001-4918 Kumar Venkatraman, R. Chekulaev, D. Tartakovskii, A.I. https://orcid.org/0000-0002-4169-5510 Hunter, C.N. https://orcid.org/0000-0003-2533-9783 Clark, J. https://orcid.org/0000-0001-9664-967X
Copyright, Publisher and Additional Information:	© The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons. org/licenses/by/4.0/.
Keywords:	Energy transfer; Excited states; Light harvesting
Dates:	Submitted: 2 December 2024 Accepted: 20 May 2026 Published (online): 23 June 2026 Published: 23 June 2026
Institution:	The University of Sheffield
Academic Units:	The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematical and Physical Sciences The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Electronic and Electrical Engineering (Sheffield)
Funding Information:	Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/S002103/1 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/S030751/1 Engineering and Physical Sciences Research Council EP/R042802/1 Engineering and Physical Sciences Research Council EP/L022613/1 EUROPEAN COMMISSION - HORIZON 2020 854126 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL / EPSRC EP/T012455/1 EUROPEAN COMMISSION - HORIZON 2020 881603 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/V007696/1 BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL BB/V006630/1 Engineering and Physical Sciences Research Council 2929545
Date Deposited:	14 Jul 2026 10:51
Last Modified:	14 Jul 2026 10:51
Status:	Published online
Publisher:	Springer Science and Business Media LLC
Refereed:	Yes
Identification Number:	10.1038/s41557-026-02186-7
Related URLs:	PubMed URL Dataset
Sustainable Development Goals:
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:243084