Triplet-sensitized and thermal isomerization of all-trans, 7-cis, 9-cis, 13-cis and 15-cis isomers of .beta.-carotene: configurational dependence of the quantum yield of isomerization via the T1 state

Kuki, Michitaka; Koyama, Yasushi; Nagae, Haruki

doi:10.1021/j100172a016

Cited by 103 publications

(103 citation statements)

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“…26,29 This hypothesis has been supported by transient Raman spectroscopy of photoexcited triplet states of various cisisomers of -carotene and SPO, which suggest more rapid dynamics for the isomerization of the 15,15′-cis carotenoid to its all-trans configuration compared to other cis-isomers of the molecules. It has been argued that cis-to-trans isomerization of 15,15′-cis carotenoid is a mechanism that enhances photoprotection.…”

mentioning

confidence: 86%

“…The cis-to-trans isomerization mechanism of 15,15′-cis-spheroidene for its photoprotective nature proposed by Boucher and Gingras, 25 and Koyama and co-workers [26][27][28][29][30] is questioned by a few researchers. 32,[35][36][37] Basically, they studied the reconstituted carotenoidless Rb.…”

Section: Does Locked-1314-cis-spheroidene Has a Crossing Potential Cmentioning

confidence: 99%

“…The calculated results, Figure 5, clearly favour the cis-over trans-conformer for dissipating the triplet state energy -the necessary rotation for reaching their respective singlet-triplet crossing points is similar for both the isomers; however, the energy required for the cis and trans isomers to reach their relevant crossing points is 32. [26][27][28][29][30] Earlier studies also claimed that any cis isomer must be more favourite than the trans in dissipating the energy because quantum yield of tripletsensitized isomerization for all the selected cis isomers is much larger than the trans-to-cis isomerization quantum yield (0.04). 33 The present study indicates that, as in the case of 15,15′-cis, 13,14-cis conformer needs only 26.4 kJ/mol (6.32 kcal/mol) to reach the singlettriplet crossing point, Figure 10b.…”

Section: Energy Dissipative Photo-protection Mechanismmentioning

confidence: 99%

“…Kuki et al 26 revealed the 15-cis to all-trans isomerization of the same carotenoid spirilloxanthin in the light and the reverse isomerization in the dark for a reduced form of RC from R. rubrum S1. By using transient Raman, transient absorption spectroscopies and by HPLC analysis of triplet-sensitized isomerization, Koyama and co-workers [27][28][29][30] showed that 15,15′-cis isomer of SPO is extremely efficient in cis-to-trans isomerization in the T 1 state.…”

mentioning

confidence: 99%

“…It has been argued that cis-to-trans isomerization of 15,15′-cis carotenoid is a mechanism that enhances photoprotection. 25,26,29,30 Later, Ohashi et al 31 made a comparison of the ground state Raman spectrum of SPO in the reaction center of Rb. sphaeroides 2.4.1 with that free in n-hexane solution and suggested that the RC-bound spheroidene takes a 15,15′-cis configuration, which is twisted around the central C15-C15′ bond.…”

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confidence: 99%

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Energy dissipative photoprotective mechanism of carotenoid spheroidene from the photoreaction center of purple bacteria Rhodobacter sphaeroides

Arulmozhiraja

Nakatani

Nakayama

et al. 2015

Phys. Chem. Chem. Phys.

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Carotenoid spheroidene (SPO) works for photoprotection in the photosynthetic reaction centers (RC) and effectively dissipates its triplet excitation energy. Sensitized cis-totrans isomerization was proposed as the possible mechanism for a singlet-triplet energy crossing for the 15,15′-cis-SPO; however, it has been questioned recently. To understand the dissipative proto-protective mechanism of this important SPO and to overcome the existing controversies on this issue, we carried out a theoretical investigation using density functional theory on the possible triplet energy relaxation mechanism through the cis-to-trans isomerization. Together with the earlier experimental observations, the possible mechanism was discussed for the triplet energy relaxation of the 15,15′-cis-SPO. The result shows that complete cis-to-trans isomerization is not necessary. Twisting C15-C15′ bond leads singlettriplet energy crossing at (14,15,15′,14′) = 77 o at the energy 32.5 kJ/mol (7.7 kcal/mol) higher than that of the T 1 15,15′-cis minimum. Further exploration of the minimum-energy intersystem crossing (MEISC) point shows that triplet relaxation could happen at a less distorted structure ( =58.4 o ) with the energy height of 6.3 kcal/mol. Another important reaction coordinate to reach the MEISC point is the bond-length alternation. The model truncation effect, the solvent effect, and the spin-orbit coupling were also investigated. The singlet-triplet crossing was also investigated for the 13,14-cis stereoisomer and locked-13,14-cis-SPO. We also discussed the origin of the natural selection of cis over trans isomer in the RC.

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mentioning

confidence: 86%

Section: Does Locked-1314-cis-spheroidene Has a Crossing Potential Cmentioning

confidence: 99%

Section: Energy Dissipative Photo-protection Mechanismmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Energy dissipative photoprotective mechanism of carotenoid spheroidene from the photoreaction center of purple bacteria Rhodobacter sphaeroides

Arulmozhiraja

Nakatani

Nakayama

et al. 2015

Phys. Chem. Chem. Phys.

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Structure of theT1-state wave function of linear polyenes

Takahashi

Watanabe

Kikuchi

1998

Int. J. Quant. Chem.

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Configuration interaction singles CIS calculations of the planar T state 1 of hexatriene, octatetraene, decapentaene, and dodecahexaene showed that the Ž . Ž . HOMO y i ª LUMO q i type single excitations contribute significantly. This is attributed to the similarity of the HOMO, LUMO, and HOMO y i, LUMO q i overlap densities which stem from nodal properties of the molecular orbitals. CASSCF calculations for hexatriene and octatetraene also showed remarkable contributions of the Ž . Ž . HOMO y i ª LUMO q i type singly excited configurations.

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The structures of S0 spheroidene in the light-harvesting (LH2) complex and S0 and T1 spheroidene in the reaction center of Rhodobacter sphaeroides 2.4.1 as revealed by Raman spectroscopy

et al. 1998

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The Raman spectrum of S0 spheroidene in the light‐harvesting (LH2) complex (LHC) and those of S0 and T1 spheroidene in the reaction center (RC) of Rhodobacter sphaeroides 2.4.1 were recorded. Comparison of the S0 Raman spectrum of the all‐trans isomer bound to the LHC of R. sphaeroides 2.4.1 with that free in n‐hexane solution suggests that the LHC‐bound carotenoid takes a flat, all‐trans configuration with possible distortion in the plane of the conjugated chain. On the other hand comparison of the S0 Raman spectrum of the 15‐cis isomer bound to the RC with that free in n‐hexane solution suggests that the RC‐bound carotenoid takes a 15‐cis configuration which is twisted around the C15(double bond)C15′ bond and distorted in the (single bond)C15H(double bond)C15′H(single bond) plane. The T1 Raman spectra of the RC‐bound spheroidene indicated substantial twisting and in‐plane distortion of the conjugated backbone. Based on the above results, a mechanism of triplet‐energy dissipation by the RC‐bound carotenoid, which involves an internal rotation around the C15(double bond)C15′ bond, is proposed. © 1996 John Wiley & Sons, Inc.

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Triplet-sensitized and thermal isomerization of all-trans, 7-cis, 9-cis, 13-cis and 15-cis isomers of .beta.-carotene: configurational dependence of the quantum yield of isomerization via the T1 state

Cited by 103 publications

References 1 publication

Energy dissipative photoprotective mechanism of carotenoid spheroidene from the photoreaction center of purple bacteria Rhodobacter sphaeroides

Energy dissipative photoprotective mechanism of carotenoid spheroidene from the photoreaction center of purple bacteria Rhodobacter sphaeroides

Structure of theT1-state wave function of linear polyenes

The structures of S0 spheroidene in the light-harvesting (LH2) complex and S0 and T1 spheroidene in the reaction center of Rhodobacter sphaeroides 2.4.1 as revealed by Raman spectroscopy

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