Magnetic perturbation of singlet-triplet transitions. Part 7.—Simultaneous electronic transitions

Evans, Denis J.; Tucker, J. N.

doi:10.1039/f29726800174

Cited by 19 publications

(9 citation statements)

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“…14 A 35.6 kcal/mol value had been based on the 0-0 band in the S 0 f T 1 absorption spectrum of ttt-DPH in chloroform in the presence of a high O 2 pressure. 37 The calculated E rel for 3 ttt is lower than the experimental triplet energy by at least 1.6 kcal/mol. A larger discrepancy between theory and experiment, in the same direction, was obtained for tt-DPB, 1 whereas theory and experiment are in much better agreement in the stilbene case.…”

Section: Discussionmentioning

confidence: 97%

Temperature Dependence of the 1,6-Diphenyl-1,3,5-hexatriene Triplet Lifetime in Solution and Theoretical Evaluation of Triplet Conformer Interconversion

et al. 2010

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The 1,6-diphenyl-1,3,5-hexatriene (DPH) triplet decay rate constant in degassed benzene is strongly temperature-dependent. Photostationary states for the fluorenone-sensitized photoisomerization of DPH in degassed methylcyclohexane (MCH) favor the all-trans isomer and become richer in the cis isomers as the temperature is increased. The results are interpreted in terms of competing decays from equilibrated triplet conformers on the basis of the experimentally derived DPH triplet potential energy surface [Saltiel, J.; Crowder, J. M.; Wang, S. J. Am. Chem. Soc. 1999, 121, 895 902; 5352]. Calculated geometries and energy differences [B3LYP/6-311+G(d,p)] are consistent with the experimental model.

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Section: Discussionmentioning

confidence: 97%

Temperature Dependence of the 1,6-Diphenyl-1,3,5-hexatriene Triplet Lifetime in Solution and Theoretical Evaluation of Triplet Conformer Interconversion

et al. 2010

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“…The relationship of the triplet energy of each of the isomeric DPH triplets, where x is either t or c, to the triplet energy of ttt -DPH is given by With reference to = 34.0 kcal/mol, ,− the triplet energies of the cis isomers are 34.3 ± 0.3, 34.2 ± 0.2, 34.6 ± 0.4 kcal/mol and for ctt -, tct -, and cct -DPH, respectively. The prediction of nearly identical triplet energies for the isomeric triplets is nicely consistent with the interpretation of fluorenone-sensitized photoisomerization quantum yields under degassed conditions .…”

Section: Discussionmentioning

confidence: 99%

Mapping the Potential Energy Surfaces of the 1,6-Diphenyl-1,3,5-hexatriene Ground and Triplet States

1999

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The relative energies of the ground state isomers of 1,6-diphenyl-1,3,5-hexatriene (DPH) in benzene are determined from the temperature dependence of the equilibrium isomer composition obtained with the use of diphenyl diselenide as isomerization catalyst. In the triplet state, DPH exists as an equilibrium mixture of all-trans (ttt), trans,cis,trans (tct), cis,trans,trans (ctt), and cis,cis,trans (cct) isomers. Under degassed conditions, photoisomerization of the triplets is primarily bimolecular, involving a quantum chain process. Oxygen eliminates the quantum chain process by efficient deactivation of DPH triplets thereby revealing the triplet state isomeric composition. The temperature dependencies of the fluorenone-sensitized photoisomerization quantum yields and photostationary states for DPH in air-saturated benzene provide two independent measures of the temperature dependence of the equilibrium contribution of the isomeric triplets. They reveal the relative energies of the DPH triplet isomers. Together with the known 34 kcal/mol triplet energy of ttt-DPH, these results define points on the potential energy surfaces of the ground and triplet states corresponding to the equilibrium geometries of the four observed DPH isomers. At these geometries the two surfaces roughly parallel each other. Complete equilibration of isomeric triplets within 100 ns requires that the energies of triplet biradical transition states be no higher than 40.3 kcal/mol. Estimated radical stabilization energies give 40.2 and 41.6 kcal/mol for the energies of biradical transition states for central and terminal bond isomerization, respectively, in the ground state of ttt-DPH.

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“…There have been no other applications of phosphorescence spectroscopy to photosynthetic Cars as far as the authors know (see also [1,10] for reviewers). In order to estimate the Car T 1 energies, the T 1 energies of shorter polyenes with the number of conjugated double bonds n ¼ 1-4, which were determined by O 2 -perturbed electronic-absorption spectroscopy [11][12][13], were extrapolated, by the use of an empirical equation, until n ¼ 13 [1]. The T 1 energies were also evaluated by the use of triplet sensitizers [14].…”

Section: Introductionmentioning

confidence: 99%

The energies and kinetics of triplet carotenoids in the LH2 antenna complexes as determined by phosphorescence spectroscopy

Rondonuwu

Taguchi

Fujii

et al. 2004

Chemical Physics Letters

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Magnetic perturbation of singlet-triplet transitions. Part 7.—Simultaneous electronic transitions

Cited by 19 publications

References 0 publications

Temperature Dependence of the 1,6-Diphenyl-1,3,5-hexatriene Triplet Lifetime in Solution and Theoretical Evaluation of Triplet Conformer Interconversion

Temperature Dependence of the 1,6-Diphenyl-1,3,5-hexatriene Triplet Lifetime in Solution and Theoretical Evaluation of Triplet Conformer Interconversion

Mapping the Potential Energy Surfaces of the 1,6-Diphenyl-1,3,5-hexatriene Ground and Triplet States

The energies and kinetics of triplet carotenoids in the LH2 antenna complexes as determined by phosphorescence spectroscopy

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