scholarly journals Photosynthetic light harvesting: excitons and coherence

2014 ◽  
Vol 11 (92) ◽  
pp. 20130901 ◽  
Author(s):  
Francesca Fassioli ◽  
Rayomond Dinshaw ◽  
Paul C. Arpin ◽  
Gregory D. Scholes
Keyword(s):  
Energy Transfer ◽  
Excited States ◽  
Quantum Coherence ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Excited Electronic State ◽  
Electronic Excitations ◽  
Open Questions ◽  
Pigment Protein Complexes ◽  
Electronically Excited

Photosynthesis begins with light harvesting, where specialized pigment–protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.

scholarly journals A photosynthetic antenna complex foregoes unity carotenoid-to-bacteriochlorophyll energy transfer efficiency to ensure photoprotection

2020 ◽  
Vol 117 (12) ◽  
pp. 6502-6508 ◽  
Author(s):  
Dariusz M. Niedzwiedzki ◽  
David J. K. Swainsbury ◽  
Daniel P. Canniffe ◽  
C. Neil Hunter ◽  
Andrew Hitchcock
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Light Harvesting Complexes ◽  
Antenna Complex ◽  
Pigment Protein Complexes

Carotenoids play a number of important roles in photosynthesis, primarily providing light-harvesting and photoprotective energy dissipation functions within pigment–protein complexes. The carbon–carbon double bond (C=C) conjugation length of carotenoids (N), generally between 9 and 15, determines the carotenoid-to-(bacterio)chlorophyll [(B)Chl] energy transfer efficiency. Here we purified and spectroscopically characterized light-harvesting complex 2 (LH2) fromRhodobacter sphaeroidescontaining theN= 7 carotenoid zeta (ζ)-carotene, not previously incorporated within a natural antenna complex. Transient absorption and time-resolved fluorescence show that, relative to the lifetime of the S1state of ζ-carotene in solvent, the lifetime decreases ∼250-fold when ζ-carotene is incorporated within LH2, due to transfer of excitation energy to the B800 and B850 BChlsa. These measurements show that energy transfer proceeds with an efficiency of ∼100%, primarily via the S1→ Qxroute because the S1→ S0fluorescence emission of ζ-carotene overlaps almost perfectly with the Qxabsorption band of the BChls. However, transient absorption measurements performed on microsecond timescales reveal that, unlike the nativeN≥ 9 carotenoids normally utilized in light-harvesting complexes, ζ-carotene does not quench excited triplet states of BChla, likely due to elevation of the ζ-carotene triplet energy state above that of BChla. These findings provide insights into the coevolution of photosynthetic pigments and pigment–protein complexes. We propose that theN≥ 9 carotenoids found in light-harvesting antenna complexes represent a vital compromise that retains an acceptable level of energy transfer from carotenoids to (B)Chls while allowing acquisition of a new, essential function, namely, photoprotective quenching of harmful (B)Chl triplets.

scholarly journals Excitation energy transfer between monomolecular layers of light harvesting LH2 and LH1-reaction centre complexes printed on a glass substrate

Lab on a Chip ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 2529-2538
Author(s):  
Xia Huang ◽  
Cvetelin Vasilev ◽  
C. Neil Hunter
Keyword(s):  
Energy Transfer ◽  
Glass Substrate ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Excitation Energy Transfer ◽  
Artificial Light ◽  
Reaction Centre ◽  
Bacterial Pigment ◽  
Pigment Protein Complexes ◽  
Monomolecular Layers

Remarkably stable artificial light-harvesting arrays capable of harvesting and trapping solar energy were fabricated using purified bacterial pigment–protein complexes.

Light harvesting in oxygenic photosynthesis: Structural biology meets spectroscopy

Science ◽  
2020 ◽  
Vol 369 (6506) ◽  
pp. eaay2058 ◽  
Author(s):  
Roberta Croce ◽  
Herbert van Amerongen
Keyword(s):  
Light Harvesting ◽  
Protein Complexes ◽  
Excitation Energy Transfer ◽  
Oxygenic Photosynthesis ◽  
Main Process ◽  
Electronic Excitations ◽  
Pigment Protein Complexes ◽  
In Series ◽  
Life On Earth

Oxygenic photosynthesis is the main process that drives life on earth. It starts with the harvesting of solar photons that, after transformation into electronic excitations, lead to charge separation in the reaction centers of photosystems I and II (PSI and PSII). These photosystems are large, modular pigment-protein complexes that work in series to fuel the formation of carbohydrates, concomitantly producing molecular oxygen. Recent advances in cryo–electron microscopy have enabled the determination of PSI and PSII structures in complex with light-harvesting components called “supercomplexes” from different organisms at near-atomic resolution. Here, we review the structural and spectroscopic aspects of PSI and PSII from plants and algae that directly relate to their light-harvesting properties, with special attention paid to the pathways and efficiency of excitation energy transfer and the regulatory aspects.

scholarly journals Energy transfer in spectrally inhomogeneous light-harvesting pigment-protein complexes of purple bacteria

1995 ◽  
Vol 69 (6) ◽  
pp. 2211-2225 ◽  
Author(s):  
S. Hess ◽  
E. Akesson ◽  
R.J. Cogdell ◽  
T. Pullerits ◽  
V. Sundström
Keyword(s):  
Energy Transfer ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Purple Bacteria ◽  
Pigment Protein Complexes

scholarly journals Theoretical Electronic and Rovibrational Studies for Anions of Interest to the DIBs

2013 ◽  
Vol 9 (S297) ◽  
pp. 344-348 ◽  
Author(s):  
R. C. Fortenberry
Keyword(s):  
Excited State ◽  
Excited States ◽  
State Of The Art ◽  
Spectroscopic Constants ◽  
Coupled Cluster ◽  
Electronic Excitations ◽  
Electronically Excited States ◽  
Coupled Cluster Theory ◽  
Electronically Excited ◽  
Enolate Anion

AbstractThe dipole-bound excited state of the methylene nitrile anion (CH2CN−) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN− and the similar methylene enolate anion, CH2CHO−. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist in the detection of these anions in the ISM, work has also been directed towards predicting vibrational frequencies and spectroscopic constants for these anions through the use of quartic force fields (QFFs). Theoretical rovibrational work on anions has thus far included studies of CH2CN−, C3H−, and is currently ongoing for similar systems.

scholarly journals Structure of the stress-related LHCSR1 complex determined by an integrated computational strategy

2021 ◽  
Author(s):  
Ingrid Guarnetti Prandi ◽  
Vladislav Sláma ◽  
Cristina Pecorilla ◽  
Lorenzo Cupellini ◽  
Benedetta Mennucci
Keyword(s):  
Structural Model ◽  
Light Harvesting ◽  
Structural Information ◽  
Protein Complexes ◽  
Complex Stress ◽  
Main Function ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Pigment Protein Complexes ◽  
Computational Strategy

Light-harvesting complexes (LHCs) are pigment-protein complexes whose main function is to capture sunlight and transfer the energy to reaction centers of photosystems. In response to varying light conditions, LH complexes also play photoregulation and photoprotection roles. In algae and mosses, a sub-family of LHCs, Light-Harvesting complex stress related (LHCSR), is responsible for photoprotective quenching. Despite their functional and evolutionary importance, no direct structural information on LHCSRs is available that can explain their unique properties. In this work we propose a structural model of LHCSR1 from the moss P. Patens, obtained through an integrated computational strategy that combines homology modeling, molecular dynamics, and multiscale quantum chemical calculations. The model is validated by reproducing the spectral properties of LHCSR1. Our model reveals the structural specificity of LHCSR1, as compared with the CP29 LH complex, and poses the basis for understanding photoprotective quenching in mosses.

Theoretical Studies of Collision-induced Energy Transfer in Electronically Excited States

1990 ◽  
Vol 94 (11) ◽  
pp. 1253-1262 ◽  
Author(s):  
M. H. Alexander ◽  
A. Berning ◽  
A. Degli Esposti ◽  
A. Joerg ◽  
A. Kliesch ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excited States ◽  
Theoretical Studies ◽  
Electronically Excited States ◽  
Electronically Excited
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