Electronic energy levels in a homologous series of unsubstituted linear polyenes

D’Amico, K. L.; Manos, Christopher; Christensen, Ronald L.

doi:10.1021/ja00526a003

Cited by 182 publications

(85 citation statements)

References 8 publications

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“…Let us now estimate the energy gap for ttbP9. DAmico et al [26] reported that the presence of two methyl groups at A g for the unsubstituted polyenes (octatetraene, pentaene, hexaene, heptaene) in 2-MB, estimated from the solvatochromic relationships established by Snyder et al [17] and their corresponding energy gaps. A g transition is almost unaffected by these substitutions".…”

Section: Resultsmentioning

confidence: 99%

Electronic Energy Levels in all‐trans Long Linear Polyenes: The Case of the 3,20‐Di(tert‐butyl)‐2,2,21,21‐tetramethyl‐all‐trans‐3,5,7,9,11,13,15,17,19‐docosanonaen (ttbp9) Conforming to Kasha's Rule

Catalán

Hopf

Mlynek

et al. 2005

Chemistry A European J

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The absorption, fluorescence and fluorescence excitation spectra for 3,20-di(tert-butyl)-2,2,21,21-tetramethyl-all-trans-3,5,7,9,11,13,15,17,19-docosanonaen (ttbP9) in dilute solutions of 2-methylbutane were recorded at temperatures over the range 120-280 K. The high photostability of this nonaene allows us to assert that it exhibits a single fluorescence and that this can be unequivocally assigned to emission from its 1(1)B(u) excited state, it being the first excited electronic state. Available photophysical data for this polyene and the wealth of information reported for shorter all-trans polyenes allow us to conclude that if the first excited electronic state for the chromophore possessed 2(1)A(g) symmetry, then the energy of such a state might have been so close to that of the 1(1)B(u) state that: 1) the radiationless internal conversion mechanism would preclude the observation of the emission from the 1(1)B(u) state reported in this work and 2) the 2(1)A(g) state reached through internal conversion would be vibrationally coupled to 1(1)B(u) and would facilitate the detection of the emission from 2(1)A(g), which was not observed in any of the solvents used in this work. The spectroscopic and photochemical implications of these findings for other polyenes are discussed.

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Section: Resultsmentioning

confidence: 99%

Electronic Energy Levels in all‐trans Long Linear Polyenes: The Case of the 3,20‐Di(tert‐butyl)‐2,2,21,21‐tetramethyl‐all‐trans‐3,5,7,9,11,13,15,17,19‐docosanonaen (ttbp9) Conforming to Kasha's Rule

Catalán

Hopf

Mlynek

et al. 2005

Chemistry A European J

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“…For neutral polyenes the solvent effect is 0.3-0.4 eV. 89 Therefore one might expect accurate theoretical values to be a little higher than experimental ones. Interestingly, the solvent effects for the butadiene and the hexatriene cations are reported to have opposite signs, increasing the excitation energy of butadiene but lowering the excitation energy of hexatriene by 0.2 eV.…”

Section: Odd-numbered Closed-shell Polyene Cationsmentioning

confidence: 99%

Theoretical Investigation of Excited States of Large Polyene Cations as Model Systems for Lightly Doped Polyacetylene

Salzner

2006

J. Chem. Theory Comput.

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Electronic excitations of polyene cations with chain lengths of up to 101 CH units were investigated as model systems for lightly doped polyacetylene (PA). Since high level ab initio calculations such as complete active space perturbation theory (CASPT2) are limited to systems with about 14 CH units, the performances of time-dependent Hartree-Fock (TDHF) and time-dependent density functional theory (TDDFT) were evaluated. It turned out that TDDFT excitations energies are much more accurate for polyene cations than for neutral polyenes. The difference between TDHF and TDDFT excitation energies for the first allowed excited state of C 49 H 51 + is only 0.30 eV with pure DFT and 0.21 eV with a hybrid functional. For open-shell systems, pure DFT is found to be superior to DFT-hybrid functionals because it does not suffer from spin-contamination. Pure TDDFT excitation energies and oscillator strengths for small openshell polyene cations compare well with high level ab initio results. Excitation energies are found to be almost independent of the geometry, i.e., the size of the defect. Localization of the defect, however, shifts oscillator strengths from the HOMO-LUMO transition to higher lying excited states of the same symmetry. Lightly doped PA is predicted to exhibit several strong absorptions below 1 eV.

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“…Solvent shifts can be as large as 0.3 eV for optically allowed transitions, even in nonpolar solvents where specific solute-solvent interactions are not expected. [9,12,79] For most of the molecules under consideration in the present review, gas-phase data are not available because of their low vapor pressure. A possible approach to experimentally evaluate solvent shifts relies on the Onsager model, which is based on a reaction-field model involving a spherical cavity.…”

Section: Solvent Shiftsmentioning

confidence: 99%

Optical Bandgaps of π‐Conjugated Organic Materials at the Polymer Limit: Experiment and Theory

2007

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In this Review, the extreme care that must be taken when predicting the optical properties of conjugated polymers via the oligomer approach, and when comparing theoretical and experimental data, is illustrated. In the first part, conceptual strategies for the correct determination of optical transitions from experimental spectra and relevant extrapolation procedures at the polymer limit are introduced. The impact of conformational, substitution, solvent, and solid‐state effects on the optical properties is discussed in light of experimental data reported for molecular backbones based on phenylene, phenylenevinylene, and thiophene repeat units. A comparison is then made between experimental results and those provided by standard quantum‐chemical methods, to assess their reliability.

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Electronic energy levels in a homologous series of unsubstituted linear polyenes

Cited by 182 publications

References 8 publications

Electronic Energy Levels in all‐trans Long Linear Polyenes: The Case of the 3,20‐Di(tert‐butyl)‐2,2,21,21‐tetramethyl‐all‐trans‐3,5,7,9,11,13,15,17,19‐docosanonaen (ttbp9) Conforming to Kasha's Rule

Electronic Energy Levels in all‐trans Long Linear Polyenes: The Case of the 3,20‐Di(tert‐butyl)‐2,2,21,21‐tetramethyl‐all‐trans‐3,5,7,9,11,13,15,17,19‐docosanonaen (ttbp9) Conforming to Kasha's Rule

Theoretical Investigation of Excited States of Large Polyene Cations as Model Systems for Lightly Doped Polyacetylene

Optical Bandgaps of π‐Conjugated Organic Materials at the Polymer Limit: Experiment and Theory

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