Photochemical electron transfer in chlorophyll-porphyrin-quinone triads: the role of the porphyrin-bridging molecule

Johnson, Douglas G.; Niemczyk, Mark P.; Minsek, David W.; Wiederrecht, Gary P.; Svec, Walter A.; Gaines, George L.; Wasielewski, Michael R.

doi:10.1021/ja00066a039

Cited by 105 publications

(74 citation statements)

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“…This results in the change in the overlap of molecular orbitals of the π-conjugated macrocycle and the NO 2 group, which determines the value of V in PET according to the through-space mechanism [39,42]. The values of V = 0.05-1.2 cm -1 obtained by us for different solvents satisfy the known Landau-Zener criterion for nonadiabatic PET reactions [45] (7)…”

Section: Deactivation Of Excited Statesmentioning

confidence: 77%

Manifestation of nonplanarity effects and charge-transfer interactions in spectral and kinetic properties of triplet states of sterically strained octaethylporphyrins

et al. 2001

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-Properties of the triplet states of octaethylporphyrins with the steric hindrance (free bases and Pd complexes) are studied by the methods of stationary and kinetic spectroscopy in the temperature range from 77 to 293 K. The mono-mesophenyl substitution results in a decrease in the quantum yield and shortening of the phosphorescence lifetime of Pd complexes by 250-3500 times in degassed toluene at 293 K. The phosphorescence quenching is caused by nonplanar dynamic conformations of the porphyrin macrocycle in the T 1 state, which also lead to the appearance of new bands at λ ~ 1000 nm in the T -T absorption spectra. As the number of meso-phenyls (Pd-octaetyltetraphenylporphyrin) increases, the quantum yield of phosphorescence further decreases ( <10 -5 ) at 293 K, the lifetime of the T 1 state shortens (<50 ns), and the efficiency of the singlet oxygen generation abruptly decreases (<0.01). The intense bathochromic emission of this compound at 705 nm with a lifetime of 1 ms at 77 K is assigned to the phosphorescence of a nonplanar conformation. Upon meso-orthonitrophenyl substitution, the quenching of phosphorescence of Pd complexes (by more than 10 4 times at 293 K) is caused by direct nonadiabatic photoinduced electron transfer from the T 1 state to the nearest charge-transfer state with the probability = (1.5-4.0) × 10 6 s -1 . The induced absorption of ortho-nitro derivatives in the region between 110 and 1400 nm is caused by mixing of pure ππ * states with charge-transfer states. © 2001 MAIK "Nauka/Interperiodica".

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Section: Deactivation Of Excited Statesmentioning

confidence: 77%

Manifestation of nonplanarity effects and charge-transfer interactions in spectral and kinetic properties of triplet states of sterically strained octaethylporphyrins

et al. 2001

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“…In going from 1 to 2 we have reduced the absolute value of AGO. In order to maintain sufficient driving force in the charge separation steps, the D2 moiety was changed from methylnaphthalene (oxidation potential E( D2)ox = [ 19,201 where lowering the oxidation potential of the bridging unit significantly enhances the charge recombination rate, although the charge separation rate is not affected. This effect was attributed to superexchange involving D-B+-A-virtual states.…”

Section: Resultsmentioning

confidence: 99%

Two-step photoinduced charge separation and unexpectedly fast one-step charge recombination in a linked donor2-donor1-acceptor system

Dijk

Wiering

Staveren

et al. 1993

Chemical Physics Letters

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Two-step photoinduced charge separation and unexpectedly fast one-step charge recombination in a linked Donor2-Donor1-Acceptor system van Dijk, S.I.; Wiering, P.G.; van Staveren, R.; van Ramesdonk, H.J.; Brouwer, A.M.; Verhoeven, J.W. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Photoinduced sequential two-step electron transfer occurs upon excitation of the 1,3_diphenylpropanedioato boron oxalate electron acceptor in a novel trichromophoric donor*-donor,-acceptor (DI-D,-A) system. The D,-D: -A-state is fluorescent, while the D2+ -D, -A-state is observed by transient absorption. The final giant dipole state, which is formed in x 90% yield, is remarkably short-lived.

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“…In experiments this is done by substituting parts of the complexes [9,10,16,17,20] or by changing the polarity of the solvent [16]. Also the geometry and size of the bridge block can be varied, and in this way the length of the subsystem through which the electron has to be transfered [9,11,[20][21][22][23] can be changed.…”

Section: Introductionmentioning

confidence: 99%

Electron Transfer in Porphyrin Complexes in Different Solvents

2000

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The electron transfer in different solvents is investigated for systems consisting of donor, bridge and acceptor. It is assumed that vibrational relaxation is much faster than the electron transfer. Electron transfer rates and final populations of the acceptor state are calculated numerically and in an approximate fashion analytically. In wide parameter regimes these solutions are in very good agreement. The theory is applied to the electron transfer in H 2 P − ZnP − Q with free-base porphyrin (H 2 P) being the donor, zinc porphyrin (ZnP) the bridge, and quinone (Q) the acceptor. It is shown that the electron transfer rates can be controlled efficiently by changing the energy of the bridging level which can be done by changing the solvent. The effect of the solvent is determined for different models.

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Photochemical electron transfer in chlorophyll-porphyrin-quinone triads: the role of the porphyrin-bridging molecule

Cited by 105 publications

References 0 publications

Manifestation of nonplanarity effects and charge-transfer interactions in spectral and kinetic properties of triplet states of sterically strained octaethylporphyrins

Manifestation of nonplanarity effects and charge-transfer interactions in spectral and kinetic properties of triplet states of sterically strained octaethylporphyrins

Two-step photoinduced charge separation and unexpectedly fast one-step charge recombination in a linked donor2-donor1-acceptor system

Electron Transfer in Porphyrin Complexes in Different Solvents

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