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Song Y, Schubert A, Maret E, Burdick RK, Dunietz BD, Geva E, Ogilvie JP. Vibronic structure of photosynthetic pigments probed by polarized two-dimensional electronic spectroscopy and ab initio calculations. Chem Sci 2019; 10:8143-8153. [PMID: 31857881 PMCID: PMC6836992 DOI: 10.1039/c9sc02329a] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/02/2019] [Indexed: 12/29/2022] Open
Abstract
Using polarized 2D spectroscopy and state-of-the-art TDDFT calculations to uncover the vibronic structure of primary photosynthetic pigments and its effect on ultrafast photoexcited dynamics.
Bacteriochlorophyll a (Bchl a) and chlorophyll a (Chl a) play important roles as light absorbers in photosynthetic antennae and participate in the initial charge-separation steps in photosynthetic reaction centers. Despite decades of study, questions remain about the interplay of electronic and vibrational states within the Q-band and its effect on the photoexcited dynamics. Here we report results of polarized two-dimensional electronic spectroscopic measurements, performed on penta-coordinated Bchl a and Chl a and their interpretation based on state-of-the-art time-dependent density functional theory calculations and vibrational mode analysis for spectral shapes. We find that the Q-band of Bchl a is comprised of two independent bands, that are assigned following the Gouterman model to Qx and Qy states with orthogonal transition dipole moments. However, we measure the angle to be ∼75°, a finding that is confirmed by ab initio calculations. The internal conversion rate constant from Qx to Qy is found to be 11 ps–1. Unlike Bchl a, the Q-band of Chl a contains three distinct peaks with different polarizations. Ab initio calculations trace these features back to a spectral overlap between two electronic transitions and their vibrational replicas. The smaller energy gap and the mixing of vibronic states result in faster internal conversion rate constants of 38–50 ps–1. We analyze the spectra of penta-coordinated Bchl a and Chl a to highlight the interplay between low-lying vibronic states and their relationship to photoinduced relaxation. Our findings shed new light on the photoexcited dynamics in photosynthetic systems where these chromophores are primary pigments.
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Affiliation(s)
- Yin Song
- Department of Physics , University of Michigan , 450 Church St , Ann Arbor , MI 48109 , USA .
| | - Alexander Schubert
- Department of Chemistry , University of Michigan , 930 N University Ave , Ann Arbor , MI 48109 , USA.,Department of Chemistry and Biochemistry , Kent State University , 1175 Risman Drive , Kent , OH 44242 , USA
| | - Elizabeth Maret
- Applied Physics Program , University of Michigan , 450 Church St , Ann Arbor , MI 48109 , USA
| | - Ryan K Burdick
- Department of Chemistry , University of Michigan , 930 N University Ave , Ann Arbor , MI 48109 , USA
| | - Barry D Dunietz
- Department of Chemistry and Biochemistry , Kent State University , 1175 Risman Drive , Kent , OH 44242 , USA
| | - Eitan Geva
- Department of Chemistry , University of Michigan , 930 N University Ave , Ann Arbor , MI 48109 , USA
| | - Jennifer P Ogilvie
- Department of Physics , University of Michigan , 450 Church St , Ann Arbor , MI 48109 , USA .
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Kosumi D, Nakagawa K, Sakai S, Nagaoka Y, Maruta S, Sugisaki M, Dewa T, Nango M, Hashimoto H. Ultrafast intramolecular relaxation dynamics of Mg- and Zn-bacteriochlorophyll a. J Chem Phys 2014; 139:034311. [PMID: 23883031 DOI: 10.1063/1.4813526] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ultrafast excited-state dynamics of the photosynthetic pigment (Mg-)bacteriochlorophyll a and its Zn-substituted form were investigated by steady-state absorption∕fluorescence and femtosecond pump-probe spectroscopic measurements. The obtained steady-state absorption and fluorescence spectra of bacteriochlorophyll a in solution showed that the central metal compound significantly affects the energy of the Qx state, but has almost no effect on the Qy state. Photo-induced absorption spectra were recorded upon excitation of Mg- and Zn-bacteriochlorophyll a into either their Qx or Qy state. By comparing the kinetic traces of transient absorption, ground-state beaching, and stimulated emission after excitation to the Qx or Qy state, we showed that the Qx state was substantially incorporated in the ultrafast excited-state dynamics of bacteriochlorophyll a. Based on these observations, the lifetime of the Qx state was determined to be 50 and 70 fs for Mg- and Zn-bacteriochlorophyll a, respectively, indicating that the lifetime was influenced by the central metal atom due to the change of the energy gap between the Qx and Qy states.
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Affiliation(s)
- Daisuke Kosumi
- The Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Osaka 558-8585, Japan.
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Jung G, Ma Y, Prall BS, Fleming GR. Ultrafast Fluorescence Depolarisation in the Yellow Fluorescent Protein due to Its Dimerisation. Chemphyschem 2005; 6:1628-32. [PMID: 16025560 DOI: 10.1002/cphc.200400653] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transient absorption spectroscopy with sub-100 fs time resolution was performed to investigate the oligomerisation behaviour of eYFP in solution. A single time constant tau(AD)=2.2+/-0.15 ps is sufficient to describe the time-resolved anisotropy decay up to at least 200 ps. The close contact of two protein barrels is deduced as the exclusive aggregation state in solution. From the final anisotropy r(infinity)=0.28+/-0.02, the underlying quaternary structure can be traced back to the somewhat distorted structure of the dimers of wt-GFP. The use of autofluorescent proteins as rulers in Förster resonance energy transfer (FRET) measurements may demand polarisation-sensitive detection of the fluorescence with high time resolution.
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Affiliation(s)
- Gregor Jung
- Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-1460, USA.
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Andersson J, Puntoriero F, Serroni S, Yartsev A, Pascher T, Polivka T, Campagna S, Sundström V. New paradigm of transition metal polypyridine complex photochemistry. Faraday Discuss 2004; 127:295-305. [PMID: 15471351 DOI: 10.1039/b316160a] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using polarization sensitive ultrafast transient absorption spectroscopy we have studied energy transfer and excited state relaxation pathways in a tetranuclear transition metal [(osmium)(ruthenium)3] polypyridine complex. Contrary to the generally accepted picture of transition metal complex photochemistry we find that ultrafast energy transfer (< or =60 fs) occurs from the excited singlet MLCT state of the peripheral Ru-chromophores to the central Os-core, in efficient competition with intersystem crossing. Energy transfer between relaxed triplet MLCT states is more than an order of magnitude slower (600 fs).
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Affiliation(s)
- Johan Andersson
- Department of Chemical Physics, Lund University, S-221 00 Lund, Sweden
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Affiliation(s)
- Pär Kjellberg
- Department of Chemical Physics, Lund University, P.O. Box 124, S-22100 Lund, Sweden
| | - Zhi He
- Department of Chemical Physics, Lund University, P.O. Box 124, S-22100 Lund, Sweden
| | - Tõnu Pullerits
- Department of Chemical Physics, Lund University, P.O. Box 124, S-22100 Lund, Sweden
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Brüggemann B, Herek JL, Sundström V, Pullerits T, May V. Microscopic Theory of Exciton Annihilation: Application to the LH2 Antenna System. J Phys Chem B 2001. [DOI: 10.1021/jp012072y] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ben Brüggemann
- Institute of Physics, Humboldt-University at Berlin, Hausvogteiplatz 5−7, 10117 Berlin, Germany, and Department of Chemical Physics, Chemical Center, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Jennifer L. Herek
- Institute of Physics, Humboldt-University at Berlin, Hausvogteiplatz 5−7, 10117 Berlin, Germany, and Department of Chemical Physics, Chemical Center, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Villy Sundström
- Institute of Physics, Humboldt-University at Berlin, Hausvogteiplatz 5−7, 10117 Berlin, Germany, and Department of Chemical Physics, Chemical Center, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Tõnu Pullerits
- Institute of Physics, Humboldt-University at Berlin, Hausvogteiplatz 5−7, 10117 Berlin, Germany, and Department of Chemical Physics, Chemical Center, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Volkhard May
- Institute of Physics, Humboldt-University at Berlin, Hausvogteiplatz 5−7, 10117 Berlin, Germany, and Department of Chemical Physics, Chemical Center, Lund University, P.O. Box 124, 221 00 Lund, Sweden
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