Ab Initio Study of Cis−Trans Photoisomerization in Stilbene and Ethylene

Quenneville, Jason; Martı́nez, Todd J.

doi:10.1021/jp021210w

Cited by 262 publications

(356 citation statements)

References 99 publications

(179 reference statements)

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“…Pyramidalization is a common feature of intersection geometries. 2,40,41 The pyramidalization angles indicated in Figure 9 are defined as where unit vectors pointing along a bond from atom A to atom B are denoted by e AB . The S 2 /S 1 MECI geometries vary to a 34 The energies are reported in electronvolts and are Relative to the neutral ground state.…”

Section: Methodsmentioning

confidence: 99%

Substituent Effects on Dynamics at Conical Intersections: α,β-Enones

et al. 2007

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. June 14, 2007; In Final Form: August 21, 2007 Femtosecond time-resolved photoelectron spectroscopy and high-level theoretical calculations were used to study the effects of methyl substitution on the electronic dynamics of the R, -enones acrolein (2-propenal), crotonaldehyde (2-butenal), methylvinylketone (3-buten-2-one), and methacrolein (2-methyl-2-propenal) following excitation to the S 2 (ππ*) state at 209 and 200 nm. We determine that following excitation the molecules move rapidly away from the Franck-Condon region, reaching a conical intersection promoting relaxation to the S 1 (nπ*) state. Once on the S 1 surface, the trajectories access another conical intersection, leading them to the ground state. Only small variations between molecules are seen in their S 2 decay times. However, the position of methyl group substitution greatly affects the relaxation rate from the S 1 surface and the branching ratios to the products. Ab initio calculations used to compare the geometries, energies, and topographies of the S 1 /S 0 conical intersections of the molecules are not able to satisfactorily explain the variations in relaxation behavior. We propose that the S 1 lifetime differences are caused by specific dynamical factors that affect the efficiency of passage through the S 1 /S 0 conical intersection.

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Section: Methodsmentioning

confidence: 99%

Substituent Effects on Dynamics at Conical Intersections: α,β-Enones

et al. 2007

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“…These values are comparable to the experimental results in n-hexane solution (∼4.6 and ∼4.1 eV), and they follow the same trends. 16 Several theoretical studies have reported the vertical excitation energies of cis-and trans-stilbene: 4.09 and 3.94 eV by the LR-TDDFT (TD-PBE0) approach, 53 6.07 and 5.74 eV by the SA-2-CAS(2,2) method, 47 and 5.73 eV for the trans isomer with MS-CASPT2. 96 It is surprising that the excitation energy difference between the SFDFT and MS-CASPT2 methods is more than 1 eV, considering that the SF-BHHLYP "active space" is comparable to the CAS(2,2) active space.…”

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confidence: 99%

“…It is interesting to compare the optimized geometry with that obtained by the SA-2-CAS(2,2)/6-31G method, which also finds a twisted-pyramidalized minimum (τ = 89°, ω = 32°). 47 A smaller pyramidalization angle at the C 1 atom implies that the SA-2-CAS(2,2) estimates a smaller charge migration than does SF-BHHLYP because the negative charge enhances the p character of the C 1 atom (cf., methyl cation vs methyl anion). Indeed, there are some differences in the optimized geometry around the C 1 atom.…”

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confidence: 99%

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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“…The state CT is below the molecular states built from the V and Z configurations of TDMAE. Its presence likely attracts the descending flux from the Z configuration, hence prevents the Z configuration to decay to the ground state through another CI as extensively documented for regular alkenes [10]. Instead CT is a fluorescent state.…”

Section: A Reminder Of the Free Tdmae Dynamicsmentioning

confidence: 89%

“…photoisomerization [7][8][9][10] or pericyclic reactions [11]) or light harvesting and energy conversion functions of chromophores in proteins [12,13]. Controlling the passage of a wavepacket through CI's has even been proposed as a strategy for the optimal control of chemical reactions [14].…”

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confidence: 99%

Dynamics of excited tetrakis(dimethylamino)ethylene solvated by argon atoms

et al. 2004

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The supersonic expansion of a mixture of the title molecule (TDMAE) with argon generates a beam carrying a log-normal distribution of TDAME(Ar) n clusters, broadly centered atn ≈ 60. The femtosecond pump-probe technique is used to investigate the excited state dynamics of these clusters up to a 220 ps delay between the pump and the probe. This documents the effect of the argon environment on the TDMAE dynamics. The TDMAE molecule is excited in the valence state V within the cluster by the pump laser at 266 nm. It undergoes deformation in the excited potential energy surface that brings the initial wavepacket to a conical intersection (CI) where the electronic configuration of the molecule switches to a Zwitterionic configuration Z. Compared to the behaviour of free TDMAE, the effect of the argon environment is a slow down of the wavepacket movement and an increase of the time scale of the V-Z energy transfer from 300 fs to 400 ± 50 fs. This slow down effect, that we call a chistera effect, differs from a standard cage effect. Here, the deforming molecule does not experience a hard sphere collision with the argon cage, rather it pushes it away. Furthermore, umbrella oscillations of the dimethylamino groups are excited when the initial wavepacket passes the CI region. Because of the argon environment, the sharp 250 fs oscillation period of the free molecules is transformed into a broad structure of 40 fs width (FWHM) centred at about 240 fs. In addition, breathing oscillations of the argon environment with respect to the TDMAE molecule are observed with a period of 410 ± 40 fs. Finally, long delays between the pump and the probe lasers allow us to investigate the non radiative energy transfer from the Z electronic configuration of TDMAE(Ar) n to a charge transfer state. The effect of the evaporation of argon atoms in the neutral and the ionised clusters has been taken into account, as its time scale accompanies that of the observed phenomena.

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Ab Initio Study of Cis−Trans Photoisomerization in Stilbene and Ethylene

Cited by 262 publications

References 99 publications

Substituent Effects on Dynamics at Conical Intersections: α,β-Enones

Substituent Effects on Dynamics at Conical Intersections: α,β-Enones

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

Dynamics of excited tetrakis(dimethylamino)ethylene solvated by argon atoms

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