Evidence for the phantom state in photoinduced cis–trans isomerization of stilbene

Kovalenko, Sergey A.; Dobryakov, A. L.; Ioffe, Ilya N.; Érnsting, N. P.

doi:10.1016/j.cplett.2010.05.022

Cited by 90 publications

(172 citation statements)

References 29 publications

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“…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%

“…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%

“…Stilbene photoisomerization takes place in both the cis-to-trans and trans-to-cis directions. It has been generally accepted that the relaxation of both cis and trans isomers involves the central CdC bond twisting motion toward the perpendicular conformation (so-called phantom state 18,25 ) on the excited-state potential energy surface (PES). A conical intersection (CI) 66À70 apparently exists near the twisted minimum.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…8,9,[13][14][15][16][17][18][19][20] Nevertheless a serious question remains unresolved. On one hand, in solution, the isomerization rate is higher by an order of magnitude compared to the rate in low pressure gases.…”

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confidence: 99%

Communication: Optical cooling of trans-stilbene

Kovalenko

Dobryakov

Pollak

et al. 2013

The Journal of Chemical Physics

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Trans-stilbene in n-hexane is excited with excess vibrational energy in the range 0–7000 cm−1. In the excited electronic state, the Raman linewidth of the ethylenic C=C stretching mode at 1570 cm−1 is followed with ∼100 fs time resolution. Upon excitation with substantial excess energy, the width of the peak is initially broad and then narrows within a few picoseconds, as observed previously by Iwata and Hamaguchi [Chem. Phys. Lett. 196, 462 (1992)]10.1016/0009-2614(92)85721-L. This narrowing is understood as being caused by cooling of the initially hot molecule, by the surrounding solvent. In this Communication, we report that upon excitation without excess energy, the width is initially relatively narrow and then broadens on a picosecond time scale. The broadening is attributed to heating of the molecule by solvent collisions. It follows that the nascent population in the excited electronic state is cold as compared with the solvent. Such reduction of the initial vibrational energy may affect the rate for the subsequent photoreaction, especially in the absence of the solvent.

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Boosting Ultrafast Trans‐Cis Photoisomerization and Intersystem Crossing in Nanocrystals of Double‐Bond Photoswitching Molecules

Pang

Deng

et al. 2023

Advanced Optical Materials

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Double‐bond photoswitching molecules typically can undergo trans→cis photoisomerization, but their photoisomerization mechanisms in the solid state have been rarely reported. Herein, the excited‐state evolutions of trans‐azobenzene (AB), trans‐stilbene (TS), and N‐benzylideneaniline (NBA) are studied to unveil the relationship between the double‐bond photoswitching molecules and the photoisomerization kinetics in the solution phase and in nanocrystal suspensions (NCS). The photoisomerization rate of NBA is the fastest among these three molecules in the solution phase due to its most apparent single‐bond feature of the central double bond in the S1 state. The free space ordered crystal configuration boosts the photoisomerization rates of AB and TS in NCS to be faster than that of the solution phase because the hindrance of the wrapping solvent is eliminated in the crystals. In contrast, when NBA is prepared into NCS, it becomes distorted into a nonplanar structure because of the asymmetrical C‐H···π interactions, resulting in NBA having a large spin‐orbital coupling (SOC) value which opens the intersystem crossing channel to generate the triplet state instead of undergoing photoisomerization in solution. Therefore, this work reveals that the crystal configuration and the molecular structure may critically determine the photophysical properties of photoswitching materials.

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Evidence for the phantom state in photoinduced cis–trans isomerization of stilbene

Cited by 90 publications

References 29 publications

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

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

Communication: Optical cooling of trans-stilbene

Boosting Ultrafast Trans‐Cis Photoisomerization and Intersystem Crossing in Nanocrystals of Double‐Bond Photoswitching Molecules

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