Singlet fission in naturally-organized carotenoid molecules

Quaranta, Annamaria; Krieger‐Liszkay, Anja; Pascal, Andrew A.; Perreau, François; Robert, Bruno; Vengris, Mikas; Llansola-Portolés, Manuel J.

doi:10.1039/d0cp04493h

Cited by 18 publications

(18 citation statements)

References 48 publications

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“…Carotenoids exhibit SF phenomena in H-aggregates and also in biological phases with significant disorder. ,− In J-aggregates, singlet fission is observed for dipolar carotenoids, although it has not been observed for nonpolar carotenoids . This apparent insensitivity to structural features of SF in carotenoids remains unexplained.…”

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confidence: 99%

Mechanism of Singlet Fission in Carotenoids from a Polyene Model System

Santra

Ray

Ghosh

2022

J. Phys. Chem. Lett.

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Singlet fission (SF) is the process of formation of multiple excitons (triplet) from a locally excited singlet state. The mechanism of SF in polyacenes has been shown to proceed via a charge transfer intermediate state. However, carotenoids are not understood in the context of SF. This is possibly due to the complicated multireference nature of the low-lying excited states of carotenoids and the presence of a dark 2 1 A g state below the optically bright 1 B u state. In this work, we show that the dark A g state in polyenes and/or carotenoids, along with the charge transfer states, plays a pivotal role in the SF process. We notice that the relative importance of these states varies with a change in geometry and the overall presence of multiple pathways is crucial to the success of the SF process in carotenoid aggregates and disordered geometries.

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confidence: 99%

Mechanism of Singlet Fission in Carotenoids from a Polyene Model System

Santra

Ray

Ghosh

2022

J. Phys. Chem. Lett.

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“…The SF in 1−4 and the parent DPH is much slower than that in (longer) diphenylpolyenes 26 and carotenoids. 30,31 In lutein and violaxanthin carotenoids, for example, a recent transient absorption study has revealed that excitation energy is transferred from S 2 to hot (higher vibrational levels of) S 1 in 150 fs, from which the conversion to 1 (TT) occurs within 1−2 ps. 31 Unlike in DPHs, no S 1 /S 2 equilibrium is achieved in the carotenoids before SF occurs from S 1 , which should be due to larger S 1 −S 2 energy gaps than in DPHs.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…SF has been reported in some kinds of molecular systems such as acenes, ,,− polyenes, − ,− carotenoids, − isobenzofurans, − and perylene diimides. − The limited amount of SF-active molecules is mainly due to the restrictive list of requirements (the energetics and electronic coupling) necessary for a compound to be able to exhibit such a phenomenon. , To develop new SF materials with desired properties, namely the efficient SF and T 1 diffusion, it would be more realistic and effective to introduce suitable substituents onto the backbones of known SF-active molecules rather than trying to discover new candidate chromophores that fulfill the strict requirements. , …”

Section: Introductionmentioning

confidence: 99%

Singlet Fission in Solid 1,6-Diphenyl-1,3,5-hexatriene Dicarboxylic Acids and Esters: Effects of Meta and Para Substitution

et al. 2022

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As an exciton multiplication process, singlet fission (SF) can potentially increase the energy conversion efficiency of solar cells and other optoelectronic devices. (E,E,E)-1,6-Diphenyl-1,3,5-hexatriene (DPH) is an air-stable SF-active chromophore having a triplet state of higher energy and longer lifetime compared with those of tetracenes and pentacenes. However, functionalization of DPH molecule by the introduction of substituents has not been fully studied yet. In this work, DPH dicarboxylic acids and esters substituted in the meta and para positions of the phenyl rings were prepared to investigate the effects of position isomerism on energetics, molecular arrangements, and solid-state SF properties. We discovered that all four trienes were SF materials. For both the acid and ester, the meta isomers exhibit faster SF and more efficient triplet diffusion than the para isomers as shown by steady-state and time-resolved fluorescence measurements with and without a magnetic field. Crystallographic analysis reveals that molecules of meta ester are arranged to form slipped-parallel stacks, whereas those of the para ester are stacked in a herringbone fashion. The better SF properties, namely the faster SF and more efficient triplet diffusion, brought about by meta substitution can be attributed to more suitable energetics and more favorable molecular arrangements for SF to occur. We also found that propionic acid DPH (PA-DPH), a commercial fluorescence probe for biomembrane studies, underwent SF in the solid state.

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“…One strategy used to increase Δ E ST (and E T ) involves incorporation of a linearly conjugated polyene system, similar to those present in conventional SF materials including carotenes − and arylated polyenes such as trans,trans,trans- 1,6-diphenylhexatriene (HT, Figure ). − However, polyenes of this type undergo facile E–Z photoisomerization and [2+2] photocyclodimerization reactions.…”

Section: Introductionmentioning

confidence: 99%

Diphenyldihydropentalenediones: Wide Singlet–Triplet Energy Gap Compounds Possessing the Planarly Fixed Diene Subunit

et al. 2022

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2,2,5,5-Tetramethyl-3,6-diphenyl-2,5-dihydropentalene-1,4-dione (PD-H) and its dimethoxy (PD-OCH3) and bis(trifluoromethyl) derivatives (PD-CF3) were developed as a new class of compounds possessing a wide excited singlet–triplet energy gap. The PD derivatives would also have a high energy level of the triplet-excited state (E T) due to the planarity of the fused-diene subunit. The results of photophysical studies revealed that the energy level of the singlet-excited state (E S) and E T of PD-H are 2.88 and 1.43 eV, respectively. These values indicate that PD-H has the energy relationship, E S > 2E T, required for it to be a singlet fission (SF) material. Moreover, the introduction of electron-donating or -withdrawing groups on the benzene rings in PD-H enables fine-tuning of E S and E T. The results of transient absorption spectroscopic studies show that PD-H, PD-OCH3, and PD-CF3 in CH2Cl2 have respective T1 lifetimes of 71, 118, and 107 μs, which are long enough to utilize its triplet exciton in other optoelectronic systems. These findings suggest that the PDs are potential candidates for SF materials with high E T levels.

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Singlet fission in naturally-organized carotenoid molecules

Abstract: We have investigated the photophysics of aggregated lutein/violaxanthin in daffodil chromoplasts. We reveal the presence of three carotenoid aggregate species, the main one composed of a mixture of lutein/violaxanthin absorbing...

Cited by 18 publications

References 48 publications

Mechanism of Singlet Fission in Carotenoids from a Polyene Model System

Mechanism of Singlet Fission in Carotenoids from a Polyene Model System

Singlet Fission in Solid 1,6-Diphenyl-1,3,5-hexatriene Dicarboxylic Acids and Esters: Effects of Meta and Para Substitution

Diphenyldihydropentalenediones: Wide Singlet–Triplet Energy Gap Compounds Possessing the Planarly Fixed Diene Subunit

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