Strategies to enhance the excitation energy-transfer efficiency in a light-harvesting system using the intra-molecular charge transfer character of carotenoids

Abstract

Strategies to enhance the excitation energy-transfer efficiency in a lightharvesting system using the intra-molecular charge transfer character of carotenoids. Faraday Discussions, 198, pp. 59-71. (doi:10.1039/c6fd00211k) This is the author's final accepted version.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/138877/ AbstractFucoxanthin is a carotenoid that is mainly found in the light-harvesting complexes from blown algae and diatoms. Due to the presence of a carbonyl group attached to the polyene chain in polar environments excitation produces an excited intra-molecular charge transfer. This intra-molecular charge transfer state plays a key role in the highly efficient (~95%) energy-transfer from fucoxanthin to chlorophyll a in the light-harvesting complexes from brown algae. In purple bacterial lightharvesting systems the efficiency of excitation energy-transfer from carotenoids to bacteriochlorophylls depends on the extent of conjugation of the carotenoids. In this study we were successful, for the first time, to incorporate fucoxanthin into the light-harvesting complex 1 from the purple photosynthetic bacterium, Rhodospirillum rubrum G9+ (a carotenoidless strain). Femtosecond pump-probe spectroscopy was applied to this reconstituted light-harvesting complex in order to determine the efficiency of excitation energy-transfer from fucoxanthin to bacteriochlorophyll a when they are bound to the light-harvesting 1 apo-proteins.

Understanding/unravelling carotenoid excited singlet states

“…This strong dipole interaction was attributed to the ICT character of the excited state of fucoxanthin, enabling it to enhance the transition dipole moment of the S 1 /ICT state. Indeed, the enhancement of the excitation energy-transfer efficiency from carotenoid to bacteriochlorophyll is demonstrated by incorporating fucoxanthin into the LH1 complexes from a purple photosynthetic bacterium [120]. However, the nature and origin of the S 1 /ICT state of carbonyl carotenoids is yet to be fully understood.…”

Changing Form and Function through Carotenoids and Synthetic Biology

“…Molecular dynamics simulations currently being applied to investigate protein-carotenoid interactions (Daskalakis, 2018) will be valuable in designing optimal interactions between photosystem proteins and nonnative carotenoids. Photosynthetic bacteria are good test beds to build and test features of this system (Nagashima et al, 2017;Yukihira et al, 2017).…”

Solvent-Dependent Characterization of Fucoxanthin through 2D Electronic Spectroscopy Reveals New Details on the Intramolecular Charge-Transfer State Dynamics

“…A better understanding of the nature and the photophysical behavior of the ICT state is crucial considering the key role it might assume in the excitation energy-transfer mechanisms at the base of the photosynthetic process in the antenna complexes, where the efficiency of the transfer between carotenoids and chlorophylls may exceed 90%. ,− …”