Inner-Sphere Electron-Transfer Reorganization Energies of Zinc Porphyrins

Amashukeli, Xenia; Gruhn, Nadine E.; Lichtenberger, Dennis L.; Winkler, Jay R.

doi:10.1021/ja0351037

Cited by 59 publications

(69 citation statements)

References 30 publications

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“…In fact, several studies have proven that the spectral features measured on thin films 1 are equivalent to those measured on better resolved gas phase spectra [18,20,[40][41][42] and can then be compared to calculated density of states (DOS). In Fig.…”

Section: Resultsmentioning

confidence: 99%

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Giovanelli

Lee

Lacaze‐Dufaure

et al. 2017

Journal of Electron Spectroscopy and Related Phenomena

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. b s t r a c tThe valence and conduction bands of a thin film of tetra(4-aminophenyl)porphyrin (TAPP) are investigated by direct and inverse photoemission as well as by comparison to density functional theory (DFT) calculations. By projecting the electronic eigenfunctions onto the molecular framework it was possible to interpret the origin of each spectroscopic feature. Although the majority of the photoemission spectrum is attributed to the unsubstituted tetraphenylporphyrin (TPP) parent molecule, several features are clearly due to the amino substitution. Substitution also has important consequences for the energy positions of the frontier orbitals and therefore on the low-energy electronic excitations. The measured electronic transport energy gap (E g = 1.85 eV) between the highest occupied molecular orbital (HOMO) and lowest unoccupied (LUMO) in TAPP is found to be significantly reduced with respect to TPP. Moreover, an increased energy separation between the two highest occupied states (HOMO and HOMO−1) is found both experimentally and by DFT calculations. Such evidence is attributed to an increased HOMO orbital destabilization due to an enhanced electron-donor character of the phenyl substituents upon amino functionalization. Finally, the above findings together with further time-dependent DFT calculations are used to interpret the effect of the amino groups on the UV-Vis absorption spectrum, namely an overall red-shift of the spectrum and remarkable intensity changes within the Q band.

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Section: Resultsmentioning

confidence: 99%

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Giovanelli

Lee

Lacaze‐Dufaure

et al. 2017

Journal of Electron Spectroscopy and Related Phenomena

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“…Small intemal reorganization energies have been reported [51] and low solvent reorganization energies are expected from the experimental behavior for the highly delocalized porphyrin anion. Therefore, many similarities have emerged between the fullerene-based and the diporphyrin triads from the TREPR investigation.…”

Section: Discussionmentioning

confidence: 97%

EPR-detected photoinduced electron transfer in three structurally related molecular triads

et al. 2006

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A comparative electron paramagnetic resonance (EPR) study has been performed on a series of structurally related molecular triads which undergo photoinduced electron transfer and differ one from the other in terms of the acceptor or donor moieties. The molecular triads, C-P-C6o , TTF-P-C6o and C-P-PF, share the same free-base tetraarylporphyrin (P) as the primary electron donor, which after light excitation initiates the electron transfer process, but differ either in terms of the electron acceptor (fullerene derivative, C6o , versus fluorinated free-base porphyrin, PF), or in terms of the final electron donor (carotenoid polyene, C, versus tetrathiafulvalene, TTF). AII these molecular triads can be considered artificial photosynthetic reaction centers in their ability to mimic several key properties of the reaction center primary photochemistry. Photoinduced charge separation and recombination have been followed by time-resolved EPR in a glass of 2-methyltetrahydrofuran and in the nematic phase of the uniaxial liquid crystal E-7. All the triads undergo photoinduced electron transfer, with the generation of charge-separated states in both the low-dielectric environment of the 2-methyltetrahydrofuran glass and in anisotropic E-7 medium. Different photochemical pathways have been recognized depending on the specific donor and acceptor moieties constituting the molecular triads. In the presence of the tetrathiafulvalene electron donor singlet-and triplet-initiated electron transfer routes are concurrently active. Recombination to the low-lying carotenoid triplet state occurs in the carotene-based triads, while singlet recombination is the only active route for the TTF-P-C6o triad, where a low-lying triplet state is lacking. Long-lived charge separation has been observed in the case of TTF-P-C6o: about 8 p.s for the singlet-born radical pair in the glassy isotropic matrix and about 7 ~ts for the triplet-born radical pair in the nematic phase of E-7. For all the molecular triads, a weak exchange interaction (J ~ I G) between the electrons in the final spin-correlated radical pair has been evaluated by simulation of the EPR spectra, providing evidence for superexchange electronic interactions mediated by the tetraarylporphyrin bridge.

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“…This relation is illustrated in Fig. 10 [254]. From this expression, the total inner-sphere reorganization energy for (1-3)a-Zn systems was estimated using the following equations:…”

Section: Inner and Outer Sphere Reorganization Energiesmentioning

confidence: 99%

Electron transfer reactions of rigid, cofacially compressed, π-stacked porphyrin–bridge–quinone systems

Kang

Iovine

Therien

2011

Coordination Chemistry Reviews

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Inner-Sphere Electron-Transfer Reorganization Energies of Zinc Porphyrins

Cited by 59 publications

References 30 publications

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

EPR-detected photoinduced electron transfer in three structurally related molecular triads

Electron transfer reactions of rigid, cofacially compressed, π-stacked porphyrin–bridge–quinone systems

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