The impact of symmetric modes on intramolecular electron transfer: A semi-classical approach

Coropceanu, Veaceslav; Boldyrev, S. I.; Risko, Chad; Brédas, Jean‐Luc

doi:10.1016/j.chemphys.2006.01.002

Cited by 6 publications

(9 citation statements)

References 49 publications

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“…It is also interesting to outline that both the Raman and the Franck−Condon factor assignments fully coincide in the description of the vibrational normal modes. Very recently, Coropceanu et al have discussed the dependence of the reorganization energy in intramolecular electron transfer related to the symmetrical vibrational modes . In this regard, the study presented here also outlines the relevant role of these modes in the derivation of the vibrational reorganization energy.…”

Section: Semiconductor Properties From Spectroscopic Datamentioning

confidence: 71%

“…Very recently, Coropceanu et al have discussed the dependence of the reorganization energy in intramolecular electron transfer related to the symmetrical vibrational modes. 30 In this regard, the study presented here also outlines the relevant role of these modes in the derivation of the vibrational reorganization energy.…”

Section: Semiconductor Properties From Spectroscopic Datamentioning

confidence: 92%

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Tetrathiafulvalene-Based Materials for Organic Field Effect Transistors. Inspection of Their Semiconductor Properties by Means of Molecular Spectroscopy and Quantum Chemistry

Casado¹,

Zgierski²,

Delgado³

et al. 2007

J. Phys. Chem. C

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The absorption and emission electronic and vibrational Raman spectra of a series of tetrathiafulvalene compounds have been recorded, assigned with the guide of density functional theory calculations, and interpreted according to their chemical nature of the introduced modifications of the tetrathiafulvalene unit. It turns out that the highest occupied molecular orbital energy can be stabilized while the lowest unoccupied molecular orbital energy is much less affected by substitution of TTF. Importantly, the substitution of tetrathiafulvalene leads to organic materials more resistant to oxidation and operational degradation. The vibrational Raman spectra have been also compared with that of the tetrathiafulvalene unit mainly focusing on the molecular structures. A vibrational splitting in the main lines of the spectra of these derivatives has been recognized and interpreted. The most prominent Raman lines of the spectra combined with the geometrical neutral → cation evolution have been related with the vibrational reorganization energy. These vibrational reorganization energies have been calculated and the trend identified with the behavior of the main Raman lines of the solid-state spectra. Relationships between the strongest Raman lines, the modes with the highest Frank−Condon activities and the vibrational modes with the main contributions to the inner-sphere reorganization energy (i.e., molecular mechanism for relaxing or dissipating energy excess or excitations) have been established. The realization of the connection among these magnitudes supposes a novelty in the field.

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Section: Semiconductor Properties From Spectroscopic Datamentioning

confidence: 71%

Section: Semiconductor Properties From Spectroscopic Datamentioning

confidence: 92%

Tetrathiafulvalene-Based Materials for Organic Field Effect Transistors. Inspection of Their Semiconductor Properties by Means of Molecular Spectroscopy and Quantum Chemistry

Casado¹,

Zgierski²,

Delgado³

et al. 2007

J. Phys. Chem. C

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“…The geometry (especially r RuN(pz) ) is, in turn, found to be sensitive to the basis set employed and is also likely to depend on the environment of the complex (e.g., in vacuo, aqueous solution, or crystalline solid) . Strictly speaking, H DA d(2) should be less than one-half the vertical gap, Δ E 12 a(2) (eq ) by a term depending on the reorganization energy due to symmetric normal modes of the solute, a correction likely to be a few hundred cm −1 . − …”

Section: Gmh Resultsmentioning

confidence: 99%

“…78 Strictly speaking, H DA d (2) should be less than one-half the vertical gap, ∆E 12 a(2) (eq 10) by a term depending on the reorganization energy due to symmetric normal modes of the solute, a correction likely to be a few hundred cm -1 . [78][79][80] C. Sensitivity to Axial Ligands. In complexes 1 and 2, a pronounced feature is backbonding from Ru to the pz π-acid, the internal axial ligand, with the external axial ligands (py and NH 3 ) playing a passive role in the DA coupling.…”

Section: Projection Analysis Of ψ D D(n) and ψ A D(nmentioning

confidence: 99%

Reduced Electronic Spaces for Modeling Donor/Acceptor Interactions

et al. 2010

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Diabatic states for donor (D) and acceptor (A) interactions in electron transfer (ET) processes are formulated and evaluated, along with coupling elements (H DA ) and effective D/A separation distances (r DA ), for reduced electronic spaces of variable size, using the generalized Mulliken Hush model (GMH), applicable to an arbitrary state space and nuclear configuration, and encompassing Robin-Day class III and as well as class II situations. Once the electronic state space is selected (a set of n g 2 adiabatic states approximated by an orbital space based on an effective 1-electron (1-e) Hamiltonian), the charge-localized GMH diabatic states are obtained as the eigenstates of the dipole moment operator, with rotations to yield locally adiabatic states for sites with multiple states. The 1-e states and energies are expressed in terms of Kohn-Sham orbitals and orbital energies. Addressing questions as to whether the estimate of H DA "improves" as one increases n, and in what sense the GMH approach "converges" with n, we carry out calculations for three mixed-valence binuclear Ru complexes, from which we conclude that the 2-state (2-st) model gives the most appropriate estimate of the effectiVe coupling, similar (to within a rms deviation of e15%) to coupling elements obtained by superexchange correction of H DA values based on larger spaces (n ) 3-6), and thus yielding a quasi-invariant value for H DA over the range explored in the calculations (n ) 2-6). An analysis of the coupling and associated D and A states shows that the 2-st coupling involves crucial mixing with intervening bridge states (D and A "tails"), while increasingly larger state spaces for the same system yield increasingly more localized D and A states (and weaker coupling), with H DA tending to approach the limit of "bare" or "through space" coupling. These results help to reconcile seemingly contradictory assertions in the recent literature regarding the proper role of multistate frameworks in the formulation of coupling for both intra-and intermolecular ET systems.The present results are compared in detail with other reported results.

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“…Mixed valence systems based on bis(triarylamines) turned out to be almost perfect model compounds to study the electron transfer (ET) properties of conjugated π-electron systems with respect to their substitution pattern. , The molecules of interest are arranged between a neutral (donor) and an oxidized triarylamine redox center (acceptor). These monoradical cations exhibit rather intense intervalence charge transfer (IV−CT) bands in the NIR-region which may be assigned to an optically induced ET. − A detailed band shape analysis of the IV−CT-band by applying the Marcus−Hush theory allows the calculation of the electronic coupling V between the redox centers and furthermore the ET-rate constant. ,,− In strongly coupled bis(triarylamine) radical cations bearing relatively short π-electron systems as bridging units, the charge is either localized at the redox centers (class II) or delocalized over the whole molecule (class III). − ,− When more extended bridging units are incorporated, additional bridge states come into play and ET may occur via a superexchange or hopping mechanism. ,,− In our previous work, we have shown that the ET properties of p -di(ethinyl)phenylene bridged systems may be controlled solely by the substituents at the phenylene subunit in such a way that either hopping or superexchange is favored. , In the special case of a bis(ethinyl)anthracene bridged radical cation 7 + solvent induced symmetry breaking was observed . In weakly polar media, the charge is “valence delocalized” with highest charge density at the bridge, whereas in polar MeCN the charge is asymmetrically localized at the redox centers.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Alternant and Nonalternant Aromatic Bridge Systems with Respect to Their ET-Properties

et al. 2007

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The bis(triarylamine) systems 1−5 were synthesized and investigated by spectroscopic and electrochemical methods. They all have an aromatic five-membered ring system in common as a central part of their π-electron bridge. The absorption spectra are presented. All compounds undergo five oxidations whereupon only the first two are reversible under semi-infinite cyclic voltammetry conditions. The spectra of the radical cations and dications of 1−5 were collected upon stepwise titration with SbCl5. All monoradical cations exhibit rather intense absorption bands in the NIR region that are assigned to optically induced charge transfer between the amine redox centers or between the amine redox center and aromatic bridge. It is suggested that with CH2Cl2 as solvent the charge in 1 + and 2 + is localized mainly at the peripheral amine redox centers whereas 3 + and 4 + are symmetrically delocalized systems with the highest charge density at the bridge. Upon increasing the solvent polarity, solvent induced symmetry breaking occurs as previously reported for the anthracene derivative 7 + . Less clear is the situation in 5 + . The nonalternant azulene derivative 4 behaves entirely different with respect to its optical and electrochemical properties if compared with the alternant naphthalene compound 6. The 1,3-azulene bridging unit turns out to mediate a strong electronic coupling combined with a low-oxidation potential.

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The impact of symmetric modes on intramolecular electron transfer: A semi-classical approach

Cited by 6 publications

References 49 publications

Tetrathiafulvalene-Based Materials for Organic Field Effect Transistors. Inspection of Their Semiconductor Properties by Means of Molecular Spectroscopy and Quantum Chemistry

Tetrathiafulvalene-Based Materials for Organic Field Effect Transistors. Inspection of Their Semiconductor Properties by Means of Molecular Spectroscopy and Quantum Chemistry

Reduced Electronic Spaces for Modeling Donor/Acceptor Interactions

Comparison of Alternant and Nonalternant Aromatic Bridge Systems with Respect to Their ET-Properties

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