Spectroelectrochemistry of carotenoids in solution

Jeevarajan, A. S.; Kispert, Lowell D.; Wu, Xiangliu

doi:10.1016/0009-2614(94)00121-9

Cited by 34 publications

(24 citation statements)

References 21 publications

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“…On the other hand, Ref. 18 report a peak for the isolated βcarotene at approximately 1.24 eV. A TDDFT calculation on the same system results again in a blue shift of about 0.4 eV.…”

Section: Resultsmentioning

confidence: 89%

Photoexcitation of a Light-Harvesting Supramolecular Triad: A Time-Dependent DFT Study

et al. 2009

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We present the first time-dependent density functional theory (TDDFT) calculation on a light-harvesting triad carotenoid-diaryl-porphyrin-C(60). Besides the numerical challenge that the ab initio study of the electronic structure of such a large system presents, we show that TDDFT is able to provide an accurate description of the excited-state properties of the system. In particular, we calculate the photoabsorption spectrum of the supramolecular assembly, and we provide an interpretation of the photoexcitation mechanism in terms of the properties of the component moieties. The spectrum is in good agreement with experimental data, and provides useful insight on the photoinduced charge-transfer mechanism which characterizes the system.

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“…On the other hand, Ref. 18 report a peak for the isolated βcarotene at approximately 1.24 eV. A TDDFT calculation on the same system results again in a blue shift of about 0.4 eV.…”

Section: Resultsmentioning

confidence: 89%

Photoexcitation of a Light-Harvesting Supramolecular Triad: A Time-Dependent DFT Study

et al. 2009

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“…1a). In view of the optically allowed nature of the D 2 ← D o transition of carotenoid radical cations (29) and the ∼10 5 /cm M extinction coefficient of this transition that is comparable with the ground‐state absorption (30), we assign the NIR spectrum of lycopene in chloroform to the D n ← D o absorption of the radical cation. For lycopene in n ‐hexane, on the other hand, the NIR absorption is rather weak and is shifted further to the red.…”

Section: Resultsmentioning

confidence: 99%

Radical Cation Generation from Singlet and Triplet Excited States of All‐trans‐Lycopene in Chloroform^¶

Han

Wul

Feng

et al. 2004

Photochem & Photobiology

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On direct photoexcitation, subpicosecond time‐resolved absorption spectroscopy revealed that the 1Bu‐type singlet excited state of all‐trans‐lycopene in chloroform was about seven times more efficient than all‐trans‐β‐carotene in generating the radical cation. The time constant of radical cation generation from the 1Bu‐type state was found to be ∼0.14 ps, a value that was comparable for the two carotenoids. On anthracene‐sensitized triplet excitation, radical cation generation was found to be much less efficient for lycopene than for β‐carotene. A slow rising phase (20‐30 μs) in the bleaching of ground‐state absorption was common for both lycopene and β‐carotene in chloroform and was ascribed to an efficient secondary reaction with a solvent radical leading to the formation of carotenoid radical cations. The reverse ordering in the tendency of the excited states of different multiplicities for the two carotenoids to generate radical cations is discussed in relation to the two carotenoids as scavengers of free radicals.

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“…An estimate of the value for the dication was made 18 on the assumption that the spectra of the cation radical and the dication for II overlapped and that a dilution factor of these occurs when the solution is stirred after stopping the electrolysis. The previously estimated values of log ) 4 for I and II are now corrected to be 5.1 for II and 5.2 for I.…”

Section: Resultsmentioning

confidence: 99%

Optical Absorption Spectra of Dications of Carotenoids

et al. 1996

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Quantitative optical absorption spectra of the cation radicals and the dications of canthaxanthin (I), -carotene (II), 7′-cyano-7′-ethoxycarbonyl-7′-apo--carotene (III), and 7′,7′-dimethyl-7′-apo--carotene (IV) in dichloromethane solution are reported. Exclusive formation of dications occurs when the carotenoids are oxidized with ferric chloride. Addition of neutral carotenoid to the dications results in equilibrium formation of cation radicals. Oxidation with iodine in dichloromethane affords only cation radicals; electrochemical oxidation under suitable conditions yields both dications and cation radicals. Values of the optical parameters depend on the nature of the oxidative medium. The oscillator strengths calculated for gas phase cation radicals and dications of I-IV using the INDO/S method show the same trend as the experimental values.

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Spectroelectrochemistry of carotenoids in solution

Cited by 34 publications

References 21 publications

Photoexcitation of a Light-Harvesting Supramolecular Triad: A Time-Dependent DFT Study

Photoexcitation of a Light-Harvesting Supramolecular Triad: A Time-Dependent DFT Study

Radical Cation Generation from Singlet and Triplet Excited States of All‐trans‐Lycopene in Chloroform^¶

Optical Absorption Spectra of Dications of Carotenoids

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Spectroelectrochemistry of carotenoids in solution

Cited by 34 publications

References 21 publications

Photoexcitation of a Light-Harvesting Supramolecular Triad: A Time-Dependent DFT Study

Photoexcitation of a Light-Harvesting Supramolecular Triad: A Time-Dependent DFT Study

Radical Cation Generation from Singlet and Triplet Excited States of All‐trans‐Lycopene in Chloroform¶

Optical Absorption Spectra of Dications of Carotenoids

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Radical Cation Generation from Singlet and Triplet Excited States of All‐trans‐Lycopene in Chloroform^¶