ChemInform Abstract: A GAS ELECTRON DIFFRACTION STUDY OF THE MOLECULAR STRUCTURE OF TRANS‐AZOBENZENE

Trætteberg, M.; Hilmo, I.; Hagen, Kolbjørn

doi:10.1002/chin.197740058

Cited by 16 publications

(35 citation statements)

References 1 publication

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“…We have therefore used DFT B3-LYP/cc-pVTZ level of theory for the next computations, since it provides reliable results and is more computationally convenient than cc-pVQZ. We remark that according to previous computational studies [35] and experimental characterisations [36,37], our calculations did provide not equal bond lengths for the two benzene rings. For trans-1-DA, we observe shorter and longer bonds alternating each other.…”

Section: Qm Single Molecule Calculationsmentioning

confidence: 60%

First-principle-based MD description of azobenzene molecular rods

et al. 2012

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Extensive density functional theory (DFT) calculations have been performed to develop a force field for the classical molecular dynamics (MD) simulations of various azobenzene derivatives. Besides azobenzene, we focused on a thiolated azobenzene's molecular rodthat has been previously demonstrated to photoisomerize from trans to cis with high yields on surfaces. The developed force field is an extension of OPLS All Atoms, and key bonding parameters are parameterized to reproduce the potential energy profiles calculated by DFT. For each of the parameterized molecule, we propose three sets of parameters: one best suited for the trans configuration, one for the cis configuration, and finally, a set able to describe both at a satisfactory degree. The quality of the derived parameters is evaluated by comparing with structural and vibrational experimental data. The developed force field opens the way to the classical MD simulations of selfassembled monolayers (SAMs) of azobenzene's molecular rods, as well as to the quantum mechanics/molecular mechanics study of photoisomerization in SAMs.

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Section: Qm Single Molecule Calculationsmentioning

confidence: 60%

First-principle-based MD description of azobenzene molecular rods

et al. 2012

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“…35 However, for both levels of theory the results are in very good agreement with data from gas-phase electron diffraction experiment ͑1.268 Å͒. 36 Moreover, the bond length obtained using the conventional ab initio HF level is significantly shorter than the experimental values mentioned above, indicating that in spite of the controversy concerning the planarity of the compounds, this level of theory does not describe properly the molecular structure of the studied compounds.…”

Section: A Equilibrium Molecular Structurementioning

confidence: 68%

“…For the compound denoted as DIAMINO, for example, x-ray diffraction results 35 suggest a planar geometry, while gas-phase electron diffraction studies 36 suggest a nonplanar geometry with the phenyl ring twisted by 30°around the N v N u C plane. A twisted molecular geometry is also found to be present in solution and had been supported by Raman measurements.…”

Section: A Equilibrium Molecular Structurementioning

confidence: 99%

Theoretical study of one- and two-photon absorption spectra of azoaromatic compounds

Silva

Krawczyk

Bartkowiak

et al. 2009

The Journal of Chemical Physics

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Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy J. Chem. Phys. 135, 194307 (2011) Population inversion of molecular nitrogen in an Ar: N2 mixture by selective resonance-enhanced multiphoton ionization J. Appl. Phys. 110, 083112 (2011) Control of vibronic excitation using quantum-correlated photons J. Chem. Phys. 135, 164304 (2011) Resonant two-photon ionization spectroscopy of jet-cooled PdSi J. Chem. Phys. 135, 134308 (2011) Optical purification of a mixture of chiral forms by dimer formation J. Chem. Phys. 135, 124304 (2011) Additional information on J. Chem. Phys. In this study, the one-and two-photon absorption spectra of seven azoaromatic compounds ͑five pseudostilbenes-type and two aminoazobenzenes͒ were theoretically investigated using the density functional theory combined with the response functions formalism. The equilibrium molecular structure of each compound was obtained at three different levels of theory: Hartree-Fock, density functional theory ͑DFT͒, and Møller-Plesset 2. The effect of solvent on the equilibrium structure and the electronic transitions of the compounds were investigated using the polarizable continuum model. For the one-photon absorption, the allowed → ‫ء‬ transition energy showed to be dependent on the molecular structures and the effect of solvent, while the n → ‫ء‬ and → ‫ء‬ ͑n͒ transition energies exhibited only a slight dependence. An inversion between the bands corresponding to the → ‫ء‬ and n → ‫ء‬ states due to the effect of solvent was observed for the pseudostilbene-type compounds. To characterize the allowed two-photon absorption transitions for azoaromatic compounds, the response functions formalism combined with DFT using the hybrid B3LYP and PBE0 functionals and the long-range corrected CAM-B3LYP functional was employed. The theoretical results support the previous findings based on the three-state model. The model takes into account the ground and two electronic excited states and has already been used to describe and interpret the two-photon absorption spectrum of azoaromatic compounds. The highest energy two-photon allowed transition for the pseudostilbene-type compounds shows to be more effectively affected ͑ϳ20%͒ by the torsion of the molecular structure than the lowest allowed transition ͑ϳ10%͒. In order to elucidate the effect of the solvent on the two-photon absorption spectra, the lowest allowed two-photon transition ͑dipolar transition͒ for each compound was analyzed using a two-state approximation and the polarizable continuum model. The results obtained reveal that the effect of solvent increases drastically the two-photon cross-section of the dipolar transition of the pseudostilbene-type compounds. In general, the features of both one-and two-photon absorption spectra of the azoaromatic compounds are well reproduced by the theoretical calculations.

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“…Since the quantum chemical calculations suggest that the investigated dyes prefer trans-2-pyridone tautomeric form, the mode of transmission of substituent effects in 1 were discussed in relation to such molecular geometry. Numerous previous investigations of molecular structure of azobenzenes 10,11 show that the introduction of alkyl substituents into 2'-and 6'-positions of the azobenzene system would be likely to result in a significant decrease in the tendency towards planarity. A number of spectroscopic and structure studies, both in the solid state and in solution [12][13][14][15] pointed out the existence of a greater non-planarity in these systems in relation to azobenzene.…”

Section: Introductionmentioning

confidence: 99%