Exclusive triplet electron transfer leading to long-lived radical ion-pair formation in an electron rich platinum porphyrin covalently linked to fullerene dyad

2020 ◽  
Vol 56 (45) ◽  
pp. 6058-6061 ◽  
Author(s):  
Dili R. Subedi ◽  
Habtom B. Gobeze ◽  
Yuri E. Kandrashkin ◽  
Prashanth K. Poddutoori ◽  
Art van der Est ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Ion Pair ◽  
Pair Formation ◽  
Triplet Excited State ◽  
Ion Pair Formation ◽  
Donor Acceptor ◽  
Platinum Porphyrin ◽  
Covalently Linked ◽  
Pair Energy

Radical ion-pair energy as high as 1.48 eV with lifetime as much as ∼1 μs, exclusively from the triplet excited state of a photosensitizer, is established in a novel donor–acceptor conjugate.

Elektronentransfer und Ionenpaar-Bildung, 47 [1] Titrationen von 1,2,4,5-Tetracyanbenzol und 7,7,8,8-Tetracyan-p-chinodimethan mit Natriummetall in aprotischen Lösungen / Electron Transfer and Ion Pair Formation, 47 [ 1 ] Titrations of 1,2,4,5-Tetracyanobenzene and 7,7,8,8-Tetracyano-p-quinodimethane with Sodium Metal in Aprotic Solutions

1996 ◽  
Vol 51 (9) ◽  
pp. 1215-1221 ◽  
Author(s):  
Hans Bock ◽  
Markus Kleine
Keyword(s):  
Electron Transfer ◽  
Ion Pair ◽  
Pair Formation ◽  
Transfer Reactions ◽  
The Novel ◽  
Band Shape ◽  
Novel Technique ◽  
Sodium Metal ◽  
Mndo Calculations ◽  
Donor Acceptor

In an especially designed and sealed glass apparatus, a combination of UV/VIS and ESR spectroscopy measurements are performed to follow electron transfer reactions in aprotic (cH⊕ < 0,1 ppm) solution. For the sodium metal reductions of the tetracyano-substituted title compounds, the novel technique provides the following detailed information: 1,2,4,5- tetracyanobenzene is uniformly reduced to its radical anion, for which additional geometryoptimized MNDO calculations predict an already significant cyanine disortion. For 7,7,8,8- tetracyano-p-quinodimethane, UV/VIS band shape analysis allows to detect in the saturated THF reduction solution the 16300 cm-1 absorption of the donor/acceptor complex formed in the equilibrium TCNQ·⊖ + TCNQ ⇆ {TCNQ·⊖···TCNQ}, which according to a literature search has been crystallized and structurally characterized in paramagnetic salts such as [Me2⊕ (TCNQ·⊖)2(TCNQ)].

Excited-state proton transfer and ion pair formation in a Cinchona organocatalyst

2012 ◽  
Vol 14 (37) ◽  
pp. 13019 ◽  
Author(s):  
Tatu Kumpulainen ◽  
Albert M. Brouwer
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation ◽  
Excited State Proton Transfer

Elektronentransfer und Ionenpaar-Bildung, 48 [1] Titrationen von Tetraphenyl-p-benzochinon mit Natrium- und Kaliummetall in aprotischen Lösungen / Electron Transfer and Ion Pair Formation, 48 [ 1 ] Titrations of Tetraphenyl-p-benzoquinone with Sodium and Potassium Metals in Aprotic Solutions

1996 ◽  
Vol 51 (9) ◽  
pp. 1222-1228 ◽  
Author(s):  
Hans Bock ◽  
Markus Kleine
Keyword(s):  
Electron Transfer ◽  
Radical Anion ◽  
Esr Spectra ◽  
Electron Transfer Reaction ◽  
Ion Pair ◽  
Pair Formation ◽  
Reaction Products ◽  
Ion Pair Formation ◽  
Electron Reduction ◽  
Sodium And Potassium

UV/VIS and ESR spectra of electron transfer reaction products in aprotic (cH⊕ < 0,1 ppm) solution can be measured in an especially designed and sealed glass apparatus and provide information on unknown facets of the microscopic pathway through the network of interdependent equilibria. For tetraphenyl-p-benzoquinone in tetrahydrofuran, single-electron reduction by a sodium metal mirror produces a red solution and, unexpectedly, after addition of 2.2.2. cryptand, contact with a potassium metal mirror generates a green (!) one. For both, ESR/ENDOR spectra prove the presence of tetraphenyl-p-benzoquinone radical anion. UV/VIS measurements provide the clue: In the equilibrium revealed by repetetive spectra recording, M·⊖solv + Me⊕solv ⇄ [M·⊖···Me⊖]solv, the radical anion is green (vm = 16900 cm-1) and the contact ion pair red (vm=18900 cm-1 ). On ion pair formation, therefore, the excitation energy of the radical anion increases by 0.25 eV.

Long-lived charge-separated states of simple electron donor-acceptor dyads using porphyrins and phthalocyanines

2008 ◽  
Vol 12 (09) ◽  
pp. 993-1004 ◽  
Author(s):  
Kei Ohkubo ◽  
Shunichi Fukuzumi
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Electron Donor ◽  
Driving Force ◽  
Reorganization Energy ◽  
Charge Recombination ◽  
Zinc Phthalocyanine ◽  
Intramolecular Electron Transfer ◽  
Triplet Excited State ◽  
Donor Acceptor

Control of electron-transfer processes is described for a number of electron donor-acceptor dyads containing porphyrins or phthalocyanines as models for the photosynthetic reaction center. The rates for intramolecular electron transfer in the dyads are controlled by the driving force and reorganization energy of electron transfer. The small reorganization energy of electron transfer reactions and large driving force of charge recombination are required to form long-lived charge-separated states. A directly linked zinc chlorin-fullerene dyad, especially, has the longest lifetime of charge-separated state at 120 s at -150 °C, which is a much longer lifetime and higher energy than those of natural photosynthetic reaction centers. On the other hand, the charge-separated states of the phthalocyanine-based donor-acceptor dyads (silicon phthalocyanine-fullerene, and zinc phthalocyanine-perylenebisimide) are short-lived since charge recombination forms the low-lying triplet excited state of the chromophore. The energy of the charge-separated state of a zinc phthalocyanine-perylenebisimide dyad is decreased by binding of metal ions to the radical anion moiety in order to be lower than the triplet excited state. This results in formation of a long-lived charge-separated state. The mechanistic viability of formation of long-lived charge-separated states is demonstrated by a variety of examples based on the Marcus theory of electron transfer.

Regioselective Bond Cleavage in the Dissociative Electron Transfer to Benzyl Thiocyanates:  The Role of Radical/Ion Pair Formation

2006 ◽  
Vol 128 (20) ◽  
pp. 6595-6604 ◽  
Author(s):  
Emad M. Hamed ◽  
Hanh Doai ◽  
Christopher K. McLaughlin ◽  
Abdelaziz Houmam
Keyword(s):  
Electron Transfer ◽  
Bond Cleavage ◽  
Ion Pair ◽  
Pair Formation ◽  
Dissociative Electron Transfer ◽  
Ion Pair Formation

scholarly journals Ion-Pair Formation in Neutral Potassium-Neutral Pyrimidine Collisions: Electron Transfer Experiments

2019 ◽  
Vol 7 ◽  
Author(s):  
Mónica Mendes ◽  
Beatriz Pamplona ◽  
Sarvesh Kumar ◽  
Filipe Ferreira da Silva ◽  
Antonio Aguilar ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation
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