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Beck WF. Intramolecular charge transfer and the function of vibronic excitons in photosynthetic light harvesting. PHOTOSYNTHESIS RESEARCH 2024:10.1007/s11120-024-01095-5. [PMID: 38656684 DOI: 10.1007/s11120-024-01095-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 03/15/2024] [Indexed: 04/26/2024]
Abstract
A widely discussed explanation for the prevalence of pairs or clusters of closely spaced electronic chromophores in photosynthetic light-harvesting proteins is the presence of ultrafast and highly directional excitation energy transfer pathways mediated by vibronic excitons, the delocalized optical excitations derived from mixing of the electronic and vibrational states of the chromophores. We discuss herein the hypothesis that internal conversion processes between exciton states on the <100 fs timescale are possible when the excitonic potential energy surfaces are controlled by the vibrational modes that induce charge transfer character in a strongly coupled system of chromophores. We discuss two examples, the peridinin-chlorophyll protein from marine dinoflagellates and the intact phycobilisome from cyanobacteria, in which the intramolecular charge-transfer (ICT) character arising from out-of-plane distortion of the conjugation of carotenoid or bilin chromophores also results in localization of the initially delocalized optical excitation on the vibrational timescale. Tuning of the ground state conformations of the chromophores to manipulate their ICT character provides a natural photoregulatory mechanism, which would control the overall quantum yield of excitation energy transfer by turning on and off the delocalized character of the optical excitations.
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Affiliation(s)
- Warren F Beck
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA.
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2
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Tumbarello F, Marcolin G, Fresch E, Hofmann E, Carbonera D, Collini E. The Energy Transfer Yield between Carotenoids and Chlorophylls in Peridinin Chlorophyll a Protein Is Robust against Mutations. Int J Mol Sci 2022; 23:5067. [PMID: 35563456 PMCID: PMC9099807 DOI: 10.3390/ijms23095067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 12/12/2022] Open
Abstract
The energy transfer (ET) from carotenoids (Cars) to chlorophylls (Chls) in photosynthetic complexes occurs with almost unitary efficiency thanks to the synergistic action of multiple finely tuned channels whose photophysics and dynamics are not fully elucidated yet. We investigated the energy flow from the Car peridinin (Per) to Chl a in the peridinin chlorophyll a protein (PCP) from marine algae Amphidinium carterae by using two-dimensional electronic spectroscopy (2DES) with a 10 fs temporal resolution. Recently debated hypotheses regarding the S2-to-S1 relaxation of the Car via a conical intersection and the involvement of possible intermediate states in the ET were examined. The comparison with an N89L mutant carrying the Per donor in a lower-polarity environment helped us unveil relevant details on the mechanisms through which excitation was transferred: the ET yield was conserved even when a mutation perturbed the optimization of the system thanks to the coexistence of multiple channels exploited during the process.
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Affiliation(s)
- Francesco Tumbarello
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (F.T.); (G.M.); (E.F.); (D.C.)
| | - Giampaolo Marcolin
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (F.T.); (G.M.); (E.F.); (D.C.)
| | - Elisa Fresch
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (F.T.); (G.M.); (E.F.); (D.C.)
| | - Eckhard Hofmann
- Faculty of Biology and Biotechnology, Ruhr-University Bochum, D-44780 Bochum, Germany;
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (F.T.); (G.M.); (E.F.); (D.C.)
| | - Elisabetta Collini
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (F.T.); (G.M.); (E.F.); (D.C.)
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3
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Dimitriev OP. Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems. Chem Rev 2022; 122:8487-8593. [PMID: 35298145 DOI: 10.1021/acs.chemrev.1c00648] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.
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Affiliation(s)
- Oleg P Dimitriev
- V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, pr. Nauki 41, Kyiv 03028, Ukraine
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4
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Jakučionis M, Gaižiu Nas I, Šulskus J, Abramavičius D. Simulation of Ab Initio Optical Absorption Spectrum of β-Carotene with Fully Resolved S0 and S2 Vibrational Normal Modes. J Phys Chem A 2022; 126:180-189. [PMID: 34985272 DOI: 10.1021/acs.jpca.1c06115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic absorption spectrum of β-carotene (β-Car) is studied using quantum chemistry and quantum dynamics simulations. Vibrational normal modes were computed in optimized geometries of the electronic ground state S0 and the optically bright excited S2 state using the time-dependent density functional theory. By expressing the S2-state normal modes in terms of the ground-state modes, we find that no one-to-one correspondence between the ground- and excited-state vibrational modes exists. Using the ab initio results, we simulated the β-Car absorption spectrum with all 282 vibrational modes in a model solvent at 300 K using the time-dependent Dirac-Frenkel variational principle and are able to qualitatively reproduce the full absorption line shape. By comparing the 282-mode model with the prominent 2-mode model, widely used to interpret carotenoid experiments, we find that the full 282-mode model better describes the high-frequency progression of carotenoid absorption spectra; hence, vibrational modes become highly mixed during the S0 → S2 optical excitation. The obtained results suggest that electronic energy dissipation is mediated by numerous vibrational modes.
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Affiliation(s)
- Mantas Jakučionis
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
| | - Ignas Gaižiu Nas
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
| | - Juozas Šulskus
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
| | - Darius Abramavičius
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
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5
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Investigating carotenoid photophysics in photosynthesis with 2D electronic spectroscopy. TRENDS IN CHEMISTRY 2021. [DOI: 10.1016/j.trechm.2021.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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6
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Regarding expressions of the oscillatory patterns in the 2D spectra of a displaced oscillator model. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111142] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Fry HC, Solomon LA, Diroll BT, Liu Y, Gosztola DJ, Cohn HM. Morphological Control of Chromophore Spin State in Zinc Porphyrin–Peptide Assemblies. J Am Chem Soc 2019; 142:233-241. [DOI: 10.1021/jacs.9b09935] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- H. Christopher Fry
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois60439, United States
| | - Lee A. Solomon
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois60439, United States
| | - Benjamin T. Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois60439, United States
| | - Yuzi Liu
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois60439, United States
| | - David J. Gosztola
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois60439, United States
| | - Hannah M. Cohn
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois60439, United States
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8
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Bubilaitis V, Hauer J, Abramavicius D. Simulations of pump probe spectra of a molecular complex at high excitation intensity. Chem Phys 2019. [DOI: 10.1016/j.chemphys.2019.110458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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9
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Toa ZSD, deGolian MH, Jumper CC, Hiller RG, Scholes GD. Consistent Model of Ultrafast Energy Transfer in Peridinin Chlorophyll-a Protein Using Two-Dimensional Electronic Spectroscopy and Förster Theory. J Phys Chem B 2019; 123:6410-6420. [DOI: 10.1021/acs.jpcb.9b04324] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zi S. D. Toa
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08540, United States
| | - Mary H. deGolian
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08540, United States
| | - Chanelle C. Jumper
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08540, United States
| | - Roger G. Hiller
- Department of Biology, Faculty of Science and Engineering, Macquarie University, Sydney NSW 2109, Australia
| | - Gregory D. Scholes
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08540, United States
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10
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Madrid-Úsuga D, Susa CE, Reina JH. Room temperature quantum coherence vs. electron transfer in a rhodanine derivative chromophore. Phys Chem Chem Phys 2019; 21:12640-12648. [PMID: 31155625 DOI: 10.1039/c9cp01398a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding electron transfer in organic molecules is of great interest in quantum materials for light harvesting, energy conversion and integration of molecules into solar cells. This, however, poses the challenge of designing specific optimal molecular structure for which the processes of ultrafast quantum coherence and electron transport are not so well understood. In this work, we investigate subpicosecond time scale quantum dynamics and electron transfer in an efficient electron acceptor rhodanine chromophoric complex. We consider an open quantum system approach to model the complex-solvent interaction, and compute the crossover from weak to strong dissipation on the reduced system dynamics for both a polar (methanol) and a non polar solvent (toluene). We show that the electron transfer rates are enhanced in the strong chromophore-solvent coupling regime, being the highest transfer rates those found at room temperature. Even though the computed dynamics are highly non-Markovian, and they may exhibit a quantum character up to hundreds of femtoseconds, we show that quantum coherence does not necessarily optimise the electron transfer in the chromophore.
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Affiliation(s)
- Duvalier Madrid-Úsuga
- Centre for Bioinformatics and Photonics (CIBioFi), Universidad del Valle, Calle 13 No. 100-00, Edificio E20 No. 1069, 760032 Cali, Colombia. and Departamento de Física, Universidad del Valle, 760032 Cali, Colombia
| | - Cristian E Susa
- Centre for Bioinformatics and Photonics (CIBioFi), Universidad del Valle, Calle 13 No. 100-00, Edificio E20 No. 1069, 760032 Cali, Colombia. and Departamento de Física y Electrónica, Universidad de Córdoba, 230002 Montería, Colombia.
| | - John H Reina
- Centre for Bioinformatics and Photonics (CIBioFi), Universidad del Valle, Calle 13 No. 100-00, Edificio E20 No. 1069, 760032 Cali, Colombia. and Departamento de Física, Universidad del Valle, 760032 Cali, Colombia
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11
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Rather SR, Scholes GD. From Fundamental Theories to Quantum Coherences in Electron Transfer. J Am Chem Soc 2019; 141:708-722. [PMID: 30412671 DOI: 10.1021/jacs.8b09059] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Photoinduced electron transfer (ET) is a cornerstone of energy transduction from light to chemistry. The past decade has seen tremendous advances in the possible role of quantum coherent effects in the light-initiated energy and ET processes in chemical, biological, and materials systems. The prevalence of such coherence effects holds a promise to increase the efficiency and robustness of transport even in the face of energetic or structural disorder. A primary motive of this Perspective is to work out how to think about "coherence" in ET reactions. We will discuss how the interplay of basic parameters governing ET reactions-like electronic coupling, interactions with the environment, and intramolecular high-frequency quantum vibrations-impact coherences. This includes revisiting the insights from the seminal work on the theory of ET and time-resolved measurements on coherent dynamics to explore the role of coherences in ET reactions. We conclude by suggesting that in addition to optical spectroscopies, validating the functional role of coherences would require simultaneous mapping of correlated electron motion and atomically resolved nuclear structure.
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Affiliation(s)
- Shahnawaz R. Rather
- Frick Chemistry Laboratory , Princeton University , Princeton , New Jersey 08544 , United States
| | - Gregory D Scholes
- Frick Chemistry Laboratory , Princeton University , Princeton , New Jersey 08544 , United States
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Guberman-Pfeffer MJ, Gascón JA. Carotenoid-Chlorophyll Interactions in a Photosynthetic Antenna Protein: A Supramolecular QM/MM Approach. Molecules 2018; 23:molecules23102589. [PMID: 30308965 PMCID: PMC6222738 DOI: 10.3390/molecules23102589] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 11/16/2022] Open
Abstract
Multichromophoric interactions control the initial events of energy capture and transfer in the light harvesting peridinin-chlorophyll a protein (PCP) from marine algae dinoflagellates. Due to the van der Waals association of the carotenoid peridinin (Per) with chlorophyll a in a unique 4:1 stoichiometric ratio, supramolecular quantum mechanical/molecular mechanical (QM/MM) calculations are essential to accurately describe structure, spectroscopy, and electronic coupling. We show that, by enabling inter-chromophore electronic coupling, substantial effects arise in the nature of the transition dipole moment and the absorption spectrum. We further hypothesize that inter-protein domain Per-Per interactions are not negligible, and are needed to explain the experimental reconstruction features of the spectrum in wild-type PCP.
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Affiliation(s)
| | - José A Gascón
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA.
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13
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Rathbone HW, Davis JA, Michie KA, Goodchild SC, Robertson NO, Curmi PMG. Coherent phenomena in photosynthetic light harvesting: part two-observations in biological systems. Biophys Rev 2018; 10:1443-1463. [PMID: 30242555 PMCID: PMC6233342 DOI: 10.1007/s12551-018-0456-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 09/06/2018] [Indexed: 10/28/2022] Open
Abstract
Considerable debate surrounds the question of whether or not quantum mechanics plays a significant, non-trivial role in photosynthetic light harvesting. Many have proposed that quantum superpositions and/or quantum transport phenomena may be responsible for the efficiency and robustness of energy transport present in biological systems. The critical experimental observations comprise the observation of coherent oscillations or "quantum beats" via femtosecond laser spectroscopy, which have been observed in many different light harvesting systems. Part Two of this review aims to provide an overview of experimental observations of energy transfer in the most studied light harvesting systems. Length scales, derived from crystallographic studies, are combined with energy and time scales of the beats observed via spectroscopy. A consensus is emerging that most long-lived (hundreds of femtoseconds) coherent phenomena are of vibrational or vibronic origin, where the latter may result in coherent excitation transport within a protein complex. In contrast, energy transport between proteins is likely to be incoherent in nature. The question of whether evolution has selected for these non-trivial quantum phenomena may be an unanswerable question, as dense packings of chromophores will lead to strong coupling and hence non-trivial quantum phenomena. As such, one cannot discern whether evolution has optimised light harvesting systems for high chromophore density or for the ensuing quantum effects as these are inextricably linked and cannot be switched off.
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Affiliation(s)
- Harry W Rathbone
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Jeffery A Davis
- Centre for Quantum and Optical Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia
| | - Katharine A Michie
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Sophia C Goodchild
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Neil O Robertson
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Paul M G Curmi
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia.
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14
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Roscioli JD, Ghosh S, LaFountain AM, Frank HA, Beck WF. Structural Tuning of Quantum Decoherence and Coherent Energy Transfer in Photosynthetic Light Harvesting. J Phys Chem Lett 2018; 9:5071-5077. [PMID: 30118229 DOI: 10.1021/acs.jpclett.8b01919] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Photosynthetic organisms capture energy from solar photons by constructing light-harvesting proteins containing arrays of electronic chromophores. Collective excitations (excitons) arise when energy transfer between chromophores is coherent, or wavelike, in character. Here we demonstrate experimentally that coherent energy transfer to the lowest-energy excitons is principally controlled in a light-harvesting protein by the temporal persistence of quantum coherence rather than by the strength of vibronic coupling. In the peridinin-chlorophyll protein from marine dinoflagellates, broad-band two-dimensional electronic spectroscopy reveals that replacing the native chlorophyll a acceptor chromophores with chlorophyll b slows energy transfer from the carotenoid peridinin to chlorophyll despite narrowing the donor-acceptor energy gap. The formyl substituent on the chlorophyll b macrocycle hastens decoherence by sensing the surrounding electrostatic noise. These findings demonstrate how quantum coherence enhances the efficiency of energy transfer despite being very short lived in light-harvesting proteins at physiological temperatures.
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Affiliation(s)
- Jerome D Roscioli
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Soumen Ghosh
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Amy M LaFountain
- Department of Chemistry , University of Connecticut , Hartford , Connecticut 06103 , United States
| | - Harry A Frank
- Department of Chemistry , University of Connecticut , Hartford , Connecticut 06103 , United States
| | - Warren F Beck
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
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15
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Abstract
The subtle details of the mechanism of energy flow from carotenoids to chlorophylls in biological light-harvesting complexes are still not fully understood, especially in the ultrafast regime. Here we focus on the antenna complex peridinin–chlorophyll a–protein (PCP), known for its remarkable efficiency of excitation energy transfer from carotenoids—peridinins—to chlorophylls. PCP solutions are studied by means of 2D electronic spectroscopy in different experimental conditions. Together with a global kinetic analysis and multiscale quantum chemical calculations, these data allow us to comprehensively address the contribution of the potential pathways of energy flow in PCP. These data support dominant energy transfer from peridinin S2 to chlorophyll Qy state via an ultrafast coherent mechanism. The coherent superposition of the two states is functional to drive population to the final acceptor state, adding an important piece of information in the quest for connections between coherent phenomena and biological functions. Energy transfer from carotenoids to chlorophylls in light-harvesting is still not fully understood, especially in the ultrafast regime. Here, the authors investigate the coherent dynamics of this process in peridinin-chlorophyll a-protein complex via 2D electronic spectroscopy and quantum chemical calculations.
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Jumper CC, van Stokkum IHM, Mirkovic T, Scholes GD. Vibronic Wavepackets and Energy Transfer in Cryptophyte Light-Harvesting Complexes. J Phys Chem B 2018; 122:6328-6340. [PMID: 29847127 DOI: 10.1021/acs.jpcb.8b02629] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Determining the key features of high-efficiency photosynthetic energy transfer remains an ongoing task. Recently, there has been evidence for the role of vibronic coherence in linking donor and acceptor states to redistribute oscillator strength for enhanced energy transfer. To gain further insights into the interplay between vibronic wavepackets and energy-transfer dynamics, we systematically compare four structurally related phycobiliproteins from cryptophyte algae by broad-band pump-probe spectroscopy and extend a parametric model based on global analysis to include vibrational wavepacket characterization. The four phycobiliproteins isolated from cryptophyte algae are two "open" structures and two "closed" structures. The closed structures exhibit strong exciton coupling in the central dimer. The dominant energy-transfer pathway occurs on the subpicosecond timescale across the largest energy gap in each of the proteins, from central to peripheral chromophores. All proteins exhibit a strong 1585 cm-1 coherent oscillation whose relative amplitude, a measure of vibronic intensity borrowing from resonance between donor and acceptor states, scales with both energy-transfer rates and damping rates. Central exciton splitting may aid in bringing the vibronically linked donor and acceptor states into better resonance resulting in the observed doubled rate in the closed structures. Several excited-state vibrational wavepackets persist on timescales relevant to energy transfer, highlighting the importance of further investigation of the interplay between electronic coupling and nuclear degrees of freedom in studies on high-efficiency photosynthesis.
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Affiliation(s)
- Chanelle C Jumper
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada.,Department of Chemistry , Princeton University , Washington Road , Princeton , New Jersey 08544 , United States
| | - Ivo H M van Stokkum
- LaserLaB, Department of Physics and Astronomy , Vrije Universiteit Amsterdam , De Boelelaan 1081 , 1081 HV Amsterdam , The Netherlands
| | - Tihana Mirkovic
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada
| | - Gregory D Scholes
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada.,Department of Chemistry , Princeton University , Washington Road , Princeton , New Jersey 08544 , United States
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West RG, Bína D, Fuciman M, Kuznetsova V, Litvín R, Polívka T. Ultrafast multi-pulse transient absorption spectroscopy of fucoxanthin chlorophyll a protein from Phaeodactylum tricornutum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:357-365. [DOI: 10.1016/j.bbabio.2018.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 02/16/2018] [Accepted: 02/24/2018] [Indexed: 11/16/2022]
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18
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Guberman-Pfeffer MJ, Greco JA, Birge RR, Frank HA, Gascón JA. Light Harvesting by Equally Contributing Mechanisms in a Photosynthetic Antenna Protein. J Phys Chem Lett 2018; 9:563-568. [PMID: 29337581 DOI: 10.1021/acs.jpclett.7b03211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report supramolecular quantum mechanics/molecular mechanics simulations on the peridinin-chlorophyll a protein (PCP) complex from the causative algal species of red tides. These calculations reproduce for the first time quantitatively the distinct peridinin absorptions, identify multichromophoric molecular excitations, and elucidate the mechanisms regulating the strongly allowed S0 (11Ag-) → S2 (11Bu+) absorptions of the bound peridinins that span a 58 nm spectral range in the region of maximal solar irradiance. We discovered that protein binding site-imposed conformations, local electrostatics, and electronic coupling contribute equally to the spectral inhomogeneity. Electronic coupling causes coherent excitations among the densely packed pigments. Complementary pairing of tuning mechanisms is the result of a competition between pigment-pigment and pigment-environment interactions. We found that the aqueous solvent works in concert with the charge distribution of PCP to produce a strong correlation between peridinin spectral bathochromism and the local dielectric environment.
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Affiliation(s)
| | - Jordan A Greco
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States
| | - Robert R Birge
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States
| | - Harry A Frank
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States
| | - José A Gascón
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States
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