Dark excited states of carotenoids: Consensus and controversy

Polı́vka, Tomáš; Sundström, Villy

doi:10.1016/j.cplett.2009.06.011

Cited by 248 publications

(296 citation statements)

References 75 publications

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“…9 When Cars are incorporated in LH complexes, the S 2 → S 1 IC process competes with Car → BChl EET, which predominantly occurs from S 2 , making the overall photoinduced dynamics significantly faster. 9,10 Extensive spectroscopic studies on Cars, both isolated and embedded in LH complexes, have revealed a more intricate energy landscape, going beyond the three-level model and calling for the inclusion of additional dark electronic states. An intermediate state with 1B u − symmetry (named S x ) mediating the S 2 → S 1 IC process has been first postulated theoretically and then experimentally demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Ultra-broadband 2D electronic spectroscopy of carotenoid-bacteriochlorophyll interactions in the LH1 complex of a purple bacterium

Maiuri

Réhault

Carey

et al. 2015

The Journal of Chemical Physics

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Articles you may be interested inUltra-broadband 2D electronic spectroscopy of carotenoid-bacteriochlorophyll interactions in the LH1 complex of a purple bacterium We investigate the excitation energy transfer (EET) pathways in the photosynthetic light harvesting 1 (LH1) complex of purple bacterium Rhodospirillum rubrum with ultra-broadband two-dimensional electronic spectroscopy (2DES). We employ a 2DES apparatus in the partially collinear geometry, using a passive birefringent interferometer to generate the phase-locked pump pulse pair. This scheme easily lends itself to two-color operation, by coupling a sub-10 fs visible pulse with a sub-15-fs near-infrared pulse. This unique pulse combination allows us to simultaneously track with extremely high temporal resolution both the dynamics of the photoexcited carotenoid spirilloxanthin (Spx) in the visible range and the EET between the Spx and the B890 bacterio-chlorophyll (BChl), whose Q x and Q y transitions peak at 585 and 881 nm, respectively, in the near-infrared. Global analysis of the one-color and two-color 2DES maps unravels different relaxation mechanisms in the LH1 complex: (i) the initial events of the internal conversion process within the Spx, (ii) the parallel EET from the first bright state S 2 of the Spx towards the Q x state of the B890, and (iii) the internal conversion from Q x to Q y within the B890. C 2015 AIP Publishing LLC.[http://dx

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Section: Introductionmentioning

confidence: 99%

Ultra-broadband 2D electronic spectroscopy of carotenoid-bacteriochlorophyll interactions in the LH1 complex of a purple bacterium

Maiuri

Réhault

Carey

et al. 2015

The Journal of Chemical Physics

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“…The S* state is usually identified via its characteristic transient absorption band located at the highenergy side of the S 1 -S n transition [59,60,63], but kinetic separation of the S* and S 1 states is possible only for carotenoids with longer conjugation lengths [64]. For β-carotene in solution, although a hint of the S* signal was observed, the S 1 and S* state lifetimes were shown to be identical [59].…”

Section: Our Results Show That β-Carotene Interacts With Bchl C Indumentioning

confidence: 99%

β-Carotene to bacteriochlorophyll c energy transfer in self-assembled aggregates mimicking chlorosomes

et al. 2010

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Carotenoids are together with bacteriochlorophylls important constituents of chlorosomes, the light-harvesting antennae of green photosynthetic bacteria. Majority of bacteriochlorophyll molecules form self-assembling aggregates inside the chlorosomes. Aggregates of bacteriochlorophylls with optical properties similar to those of chlorosomes can also be prepared in non-polar organic solvents or in aqueous environments when a suitable non-polar molecule is added. In this work, the ability of β-carotene to induce aggregation of bacteriochlorophyll c in aqueous buffer was studied. Excitation relaxation and energy transfer in the carotenoid-bacteriochlorophyll assemblies were measured using femtosecond and nanosecond transient absorption spectroscopy. A fast, ~100-fs energy transfer from the S 2 state of β-carotene to bacteriochlorophyll c was revealed, while no evidence for significant energy transfer from the S 1 state was found. Picosecond formation of the carotenoid triplet state (T 1 ) was observed, which was likely generated by singlet homo-fission from the S 1 state of β-carotene. *Manuscript Click here to view linked References 2 IntroductionChlorosomes of green photosynthetic bacteria are the most efficient light-harvesting complexes in Nature [1]. In addition, chlorosomes differ from other photosynthetic complexes in that they lack a protein scaffold housing pigments. Instead, bacteriochlorophyll (BChl) c, dor e molecules found in the interior of the chlorosome are present in the form of selforganized aggregates [2,3]. Proteins are located only in the chlorosome baseplate and envelope [4,5]. Other constituents of chlorosomes are lipids, quinones, and carotenoids [2,3].Lipids are probably part of the chlorosome envelope, together with proteins [6,7]. Quinones are involved in a protective redox-dependent excitation energy quenching mechanism [8], while carotenoids have both light harvesting and photoprotective functions [9][10][11][12][13][14][15]. Singlet excitation energy transfer from carotenoid to aggregated BChls with efficiency between 50 and 80% has been determined in chlorosomes [9,12,14]. The dominant energy transfer pathway proceeds via the carotenoid S 2 state with a fast rate constant of ~(100 fs) -1 [14]. In addition, it was suggested that carotenoids are important for the biogenesis of the chlorosome baseplate and its attachment to the cytoplasmic membrane [16,17].BChl aggregates are organized in curved lamellar structures in chlorosomes [18][19][20][21].Relatively polar chlorin rings of BChls assemble into lamellar layers via several specific interactions; however, the actual molecular arrangement is still a matter of debate [21][22][23].The lamellar layers held together by hydrophobic interactions between interdigitated esterifying alcohols of BChls [18,24]. The hydrophobic space between the chlorin layers is occupied by carotenoids and quinones, together with esterifying alcohols [19].Self-organized aggregates of chlorosomal BChls with spectral properties similar to those of chlorosom...

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“…11,12 There have been debates over the intermediate dark state between the S 2 and S 1 state of many carotenoids [10][11][12]28 but it lacks more experimental and theoretical evidences to unveil the exact nature of the S*/hot S 1 state. We also found that the intensity of the S*/hot S 1 absorption band increased 2-3 times when an excess-energy excitation of 405 nm was used instead of a 490 nm excitation.…”

Section: -19mentioning

confidence: 99%

Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

Son¹,

Lee

Pang³

2014

Bulletin of the Korean Chemical Society

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Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-β-caroten-8'-al and 7',7'-dicyano-7'-apo-β-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-β-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the S 2 and S 1 excited states.

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Dark excited states of carotenoids: Consensus and controversy

Cited by 248 publications

References 75 publications

Ultra-broadband 2D electronic spectroscopy of carotenoid-bacteriochlorophyll interactions in the LH1 complex of a purple bacterium

Ultra-broadband 2D electronic spectroscopy of carotenoid-bacteriochlorophyll interactions in the LH1 complex of a purple bacterium

β-Carotene to bacteriochlorophyll c energy transfer in self-assembled aggregates mimicking chlorosomes

Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

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