An ab initio structural and vibrational analysis of gauche,trans,trans- and gauche,cis,trans-hexa-1,3,5-trienes

Panchenko, Yu. N.; Krasnoshchiokov, S.V.; George, Philip; Bock, Charles W.

doi:10.1007/bf00671976

Cited by 25 publications

(6 citation statements)

References 55 publications

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“…The results of these calculations were presented previously 15 and are summarized in Table . Our values for the properties of the rotamers are in good agreement with previous calculations on conjugated polyenes and are sufficient for a qualitative or semiquantitative description of the population dynamics. , …”

Section: Discussionsupporting

confidence: 89%

“…Our values for the properties of the rotamers are in good agreement with previous calculations on conjugated polyenes and are sufficient for a qualitative or semiquantitative description of the population dynamics. 46,47 The Gaussian 94 calculations may also be used to describe the harmonic potential surface for vibrational motion in each of the three rotational conformations. The vibrational partition function for a harmonic oscillator may be used to describe, at least qualitatively, the energy distribution in a hot hexatriene molecule.…”

Section: Discussionmentioning

confidence: 99%

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Ultrafast Polyene Dynamics in Solution: The Conformational Relaxation and Thermalization of Highly Excited cis-1,3,5-Hexatriene as a Function of Initial Conformation and Solvent

et al. 1998

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Femtosecond transient absorption spectroscopy has been used to investigate the ground and excited-state dynamics of cis-1,3,5-hexatriene (Z-HT) and 1,3-cyclohexadiene following excitation to the strongly allowed 1B state in cyclohexane and n-hexadecane solvents. The internal conversion from the excited state manifold to produce vibrationally excited ground electronic state Z-HT occurs with rates of ca. 2−4 ps-1. The relaxation of highly excited Z-HT is used to probe the solvent−solute interaction and the influence of solvent on the competition between thermalization and single-bond isomerization dynamics. The data are also used to compare and contrast the hexatriene relaxation as a function of solute initial conditions (cZc-HT vs tZt-HT). A formalism for transforming the observed spectral data into time-dependent photoproduct yields is developed. These data are then compared with time-dependent quantum yields obtained from a transition state, rate equation approach to modeling the anticipated population dynamics. The detailed analysis of the results presented here are compared with the analysis of Lochbrunner et al. [Lochbrunner, S.; Fuss, W.; Schmid, W. E.; Kompa, K.-L. J. Phys. Chem. A 1998, 102, 9334. In press.] for the conformational relaxation of highly excited Z-HT in ethanol. Although the conformational evolution observed in hexadecane and cyclohexane are similar, the decays of cZc-HT and cZt-HT appear to be substantially faster in ethanol. These results are discussed in the context of Kramers theory for condensed phase reaction dynamics.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Ultrafast Polyene Dynamics in Solution: The Conformational Relaxation and Thermalization of Highly Excited cis-1,3,5-Hexatriene as a Function of Initial Conformation and Solvent

et al. 1998

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“…Similar findings have also been carefully documented by us for buta-1,3-diene [32], hexa-1,3,5-triene [35], octa-1,3,5,7-tetraene [36], and deca-1,3,5,7,9-pentaene [37].…”

Section: Resultssupporting

confidence: 78%

Predictive abilities of scaled quantum mechanical molecular force fields: application to 2,3-dimethylbuta-1,3-diene

Panchenko

Bock²,

Larkin

et al. 2008

Struct Chem

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In connection with the appearance of new experimental vibrational data on the high-energy rotational isomer of 2,3-dimethylbuta-1,3-diene (I) in a low-temperature matrix and in neat crystals, the ab initio-based vibrational analysis of this molecule has been re-evaluated. Calculated wavenumbers derived from a scaled quantummechanical force field analysis at the MP2(FC)/aug-ccpVDZ//MP2(FC)/aug-cc-pVDZ computational level are compared with experimental data. Several reassignments of the fundamental wavenumbers for I have been suggested in the course of the current analysis, and the existence of a high-energy non-planar s-gauche conformer of 2,3-dimethylbuta-1,3-diene has been confirmed.

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“…Our values for the properties of the rotamers are in excellent agreement with previous calculations. [24][25][26] Compared to the isomerization barriers determined for butadiene and octatetraene, the barriers for isomerization in Z-HT appear somewhat low. However, barriers calculated for E-HT in the same manner are in excellent agreement with the expected trend.…”

Section: B Single Bond Isomerization Dynamicsmentioning

confidence: 99%

The ultrafast ground and excited state dynamics of cis -hexatriene in cyclohexane

Pullen

Anderson

Walker

et al. 1997

The Journal of Chemical Physics

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One-and two-color kinetics have been combined with broadband ultraviolet transient absorption spectroscopy in the 265-300 nm region to elucidate the photophysics of cis-hexatriene in cyclohexane solvent. The lowest singlet excited state, the 2 1 A 1 state, is observed to have a lifetime of 200Ϯ50 fs. The ground-state hexatriene is produced vibrationally hot. The excess vibrational energy permits ultrafast isomerization around the CC single bonds in hexatriene. This results in a dynamic equilibrium of the three cis-hexatriene rotamers, which then relaxes multiexponentially to the room-temperature distribution in which the di-s-trans-Z-hexatriene form predominates. The peak of the mono-s-trans ͑cZt-HT͒ population is estimated to be ϳ50%. Vibrational cooling results in trapping of a small amount, ϳ8%, of cZt-HT that relaxes on a much longer time scale as the barrier to isomerization becomes important. An estimate of the absorption spectrum of cZt-HT is deduced from analysis of the spectral data at 50 ps.

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An ab initio structural and vibrational analysis of gauche,trans,trans- and gauche,cis,trans-hexa-1,3,5-trienes

Cited by 25 publications

References 55 publications

Ultrafast Polyene Dynamics in Solution: The Conformational Relaxation and Thermalization of Highly Excited cis-1,3,5-Hexatriene as a Function of Initial Conformation and Solvent

Ultrafast Polyene Dynamics in Solution: The Conformational Relaxation and Thermalization of Highly Excited cis-1,3,5-Hexatriene as a Function of Initial Conformation and Solvent

Predictive abilities of scaled quantum mechanical molecular force fields: application to 2,3-dimethylbuta-1,3-diene

The ultrafast ground and excited state dynamics of cis -hexatriene in cyclohexane

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