Time-resolved fluorescence spectra of cis-stilbene in hexane and acetonitrile

Sajadi, Mohsen; Dobryakov, A. L.; Garbin, Enrico; Érnsting, N. P.; Kovalenko, Sergey A.

doi:10.1016/j.cplett.2010.02.034

Cited by 44 publications

(69 citation statements)

References 26 publications

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“…Experimental results indicate a negligibly small barrier along the isomerization path. 17,24,25,27,30,34 The SF-BHHLYP calculations support the reaction from cis to the perpendicular conformation. The FC point for the cis isomer is at (τ,ω) = (5°,1°)…”

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confidence: 98%

“…However, there are some striking differences between the cis-to-trans and trans-to-cis isomerization processes. First, the isomerization proceeds much faster in the former (∼2 ps) 7,8,11,14,16,18,24,25,27,32 than in the latter (10À200 ps). 9,10,24,25,36 The experiments illustrate that there is a relatively large barrier (∼3 kcal/mol) on the trans-to-cis isomerization path, 3,4,6,31 while the cis-to-trans reaction involves a negligible barrier or a barrierless process.…”

Section: Introductionmentioning

confidence: 99%

“…First, the isomerization proceeds much faster in the former (∼2 ps) 7,8,11,14,16,18,24,25,27,32 than in the latter (10À200 ps). 9,10,24,25,36 The experiments illustrate that there is a relatively large barrier (∼3 kcal/mol) on the trans-to-cis isomerization path, 3,4,6,31 while the cis-to-trans reaction involves a negligible barrier or a barrierless process. 17,24,27,30,34 Second, in the cisstilbene isomerization reaction, a cyclization product, 4a,4b-dihydrophenanthrene (DHP), is observed along with the trans isomer product, although the experimental quantum yield is relatively small (0.10) compared to that of the trans isomer (0.35).…”

Section: Introductionmentioning

confidence: 99%

“…17,113 The SF-BHHLYP emission energy at the (S 1 ) DHP point is calculated to be 1.12 eV, which is at variance with the experimental fluorescence energy (∼3 eV) expected to be from the cis minimum. In addition, a very weak DHP emission 1,24,25 indicates that the fluorescence decay is an inefficient mechanism. The radiationless decay is also suppressed at the DHP minimum due to the relatively large energy gap (1.12 eV).…”

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confidence: 99%

“…110 Now, consider the trans-to-cis isomerization reaction. The trans-to-cis isomerization proceeds very slowly (10À200 ps), 9,10,24,25,36 and such a slow process is attributed to a large barrier along the reaction coordinate. The barrier height has been estimated to be ∼3.3 kcal/mol by experiment 3,4,6,32 and recently computed to be 2.1 kcal/mol (3.9 kcal/mol before the ZPE correction) 48 by adding the CASPT2 PT2 correlation energy with a SA-2-CAS(2,2) reference to the SA-5-CAS (14,12) energy.…”

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confidence: 99%

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Photoisomerization of Stilbene: A Spin-Flip Density Functional Theory Approach

2011

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The photoisomerization process of 1,2-diphenylethylene (stilbene) is investigated using the spin-flip density functional theory (SFDFT), which has recently been shown to be a promising approach for locating conical intersection (CI) points (Minezawa, N.; Gordon, M. S. J. Phys. Chem. A2009, 113, 12749). The SFDFT method gives valuable insight into twisted stilbene to which the linear response time-dependent DFT approach cannot be applied. In contrast to the previous SFDFT study of ethylene, a distinct twisted minimum is found for stilbene. The optimized structure has a sizable pyramidalization angle and strong ionic character, indicating that a purely twisted geometry is not a true minimum. In addition, the SFDFT approach can successfully locate two CI points: the twisted-pyramidalized CI that is similar to the ethylene counterpart and another CI that possibly lies on the cyclization pathway of cis-stilbene. The mechanisms of the cis-trans isomerization reaction are discussed on the basis of the two-dimensional potential energy surface along the twisting and pyramidalization angles. Disciplines Chemistry CommentsReprinted (adapted) with permission from

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confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Photoisomerization of Stilbene: A Spin-Flip Density Functional Theory Approach

2011

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Ultrafast Photochemistry of Dithizonatophenylmercury(II)

et al. 2011

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The initial photochromic reaction of dithizonatophenylmercury(II) in solution was investigated by femtosecond transient absorption spectroscopy. Ultrafast excitation within less than 100 fs caused a radiationless photoreaction with a time constant of 1.5 ps, which is interpreted as C=N isomerization through a conical intersection. The orthogonally twisted intermediate state was observed through its excited-state absorption. Bifurcation along pathways towards the ground states of the orange cis and blue trans configurations occurs below the funnel of the conical intersection. The photochromism of the title compound in a very polar solvent such as methanol is observed for the first time.

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