Cation radicals of tetraalkylprophyrins

Fajer, J.; Dc, Borg; Forman, A.; Ad, Adler; Varad,

doi:10.1021/ja00811a055

Cited by 36 publications

(25 citation statements)

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“…Given the relatively small g -factor difference between the radicals that comprise each SQP, the hyperfine interaction primarily determines |S⟩ ↔ |T +1 ⟩ mixing. However, the mean hyperfine fields of 1 and 2 are only 1.46 and 1.38 mT, respectively, using models that employ previously reported values for the radicals. , Using these mean hyperfine fields and a previously reported model (see Supporting Infomation), the resulting rate constants for hyperfine mixing of 1,3 (ZnP •+ -An-NDI •‑ ) and 1,3 (ZnP •+ -An-NDI 2 •‑ ) are 4.1 × 10 6 s –1 and 3.9 × 10 6 s –1 , respectively. Given the similarities of the two estimated hyperfine contributions, these interactions do not adequately account for the differences in line shape and width of the field dependent 3* ZnP yield data for 1 and 2 (Figure ).…”

Section: Discussionmentioning

confidence: 82%

“…However, the mean hyperfine fields of 1 and 2 are only 1.46 and 1.38 mT, respectively, using models 57 that employ previously reported values for the radicals. 41,72 Using these mean hyperfine fields and a previously reported model (see Supporting Infomation), 73 the resulting rate constants for hyperfine mixing of 1,3 (ZnP •+ -An-NDI •-) and 1,3 (ZnP •+ -An-NDI 2…”

Section: •-mentioning

confidence: 99%

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Charge Transfer and Spin Dynamics in a Zinc Porphyrin Donor Covalently Linked to One or Two Naphthalenediimide Acceptors

et al. 2021

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Quantum coherence effects on charge transfer and spin dynamics in a system having two degenerate electron acceptors are studied using a zinc 5,10,15-tri(n-pentyl)-20-phenylporphyrin (ZnP) electron donor covalently linked to either one or two naphthalene-1,8:4,5-bis(dicarboximide) (NDI) electron acceptors using an anthracene (An) spacer, ZnP-An-NDI (1) and ZnP-An-NDI2 (2), respectively. Following photoexcitation of 1 and 2 in toluene at 295 K, femtosecond transient absorption spectroscopy shows that the electron transfer (ET) rate constant for 2 is about three times larger than that of 1, which can be accounted for by the statistical nature of incoherent ET as well as the electron couplings for the charge separation reactions. In contrast, the rate constant for charge recombination (CR) of 1 is about 25% faster than that of 2. Using femtosecond transient infrared spectroscopy and theoretical analysis, we find that the electron on NDI2 •– in 2 localizes onto one of the two NDIs prior to CR, thus precluding electronically coherent CR from NDI2 •–. Conversely, CR in both 1 and 2 is spin coherent as indicated by the observation of a resonance in the 3*ZnP yield following CR as a function of applied magnetic field, giving spin–spin exchange interaction energies of 2J = 210 and 236 mT, respectively, where the line width of the resonance for 2 is greater than 1. These data show that while CR is a spin-coherent process, incoherent hopping of the electron between the two NDIs in 2, consistent with the lack of delocalization noted above, results in greater spin decoherence in 2 relative to 1.

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Section: Discussionmentioning

confidence: 82%

Section: •-mentioning

confidence: 99%

Charge Transfer and Spin Dynamics in a Zinc Porphyrin Donor Covalently Linked to One or Two Naphthalenediimide Acceptors

et al. 2021

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“…This is in accord with ESR. 56 The second oxidation gives a -dication with a 3 A 2g state. In the reduction stages, four electrons are accommodated in the LUMO 2e g (*), again in agreement with experiment.…”

Section: Zntppmentioning

confidence: 99%

Electronic structure and bonding in metal porphyrins, metal=Fe, Co, Ni, Cu, Zn

Liao

Scheiner

2002

The Journal of Chemical Physics

414

307

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A systematic theoretical study of the electronic structure and bonding in metal meso-tetraphenyl porphines MTPP, MϭFe, Co, Ni, Cu, Zn has been carried out using a density functional theory method. The calculations provide a clear elucidation of the ground states for the MTPPs and for a series of ͓MTPP͔ x ions (xϭ2ϩ, 1ϩ, 1Ϫ, 2Ϫ, 3Ϫ, 4Ϫ͒, which aids in understanding a number of observed electronic properties. The calculation supports the experimental assignment of unligated FeTPP as 3 A 2g , which arises from the configuration (d xy) 2 (d z 2) 2 (d xz) 1 (d yz) 1. The calculated M-TPP binding energies, ionization potentials, and electron affinities are in good agreement with available experimental data. The influence of axial ligands and peripheral substitution by fluorine are in accord with the experimental observation that not only half-wave potentials (E 1/2) of electrode reactions, but also the site of oxidation/reduction, may be dependent on the porphyrin basicity and the type of axial ligand coordination.

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“…P AE+ or that the unpaired electrons represent other light-induced defects located in surface sites rather than in the bulk of the sample -they are produced by oxidation of the porphyrins. It is necessary to note that above-mentioned line parameters correspond perfectly to those of ESR lines of porphyrins [29] and are similar to those of phthalocyanines [30]. It is symptomatic that the g-values of P and 2P measured in solution are the same.…”

Section: Resultsmentioning

confidence: 76%

Charge transfer in fullerene – porphyrin-derived dyads studied with light-induced electron spin resonance

et al. 2007

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Cation radicals of tetraalkylprophyrins

Abstract: relation of log (K/Ka)n values with . Mr. James Fukunaga provided the least-squares fitting results reported herein and useful discussions. We are indebted to Professor B. M. Wepster for communication of unpublished results.

Cited by 36 publications

References 0 publications

Charge Transfer and Spin Dynamics in a Zinc Porphyrin Donor Covalently Linked to One or Two Naphthalenediimide Acceptors

Charge Transfer and Spin Dynamics in a Zinc Porphyrin Donor Covalently Linked to One or Two Naphthalenediimide Acceptors

Electronic structure and bonding in metal porphyrins, metal=Fe, Co, Ni, Cu, Zn

Charge transfer in fullerene – porphyrin-derived dyads studied with light-induced electron spin resonance

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