Observation of Hole Transfer through DNA by Monitoring the Transient Absorption of Pyrene Radical Cation

2001 ◽  
Vol 123 (50) ◽  
pp. 12688-12689 ◽  
Author(s):  
Kiyohiko Kawai ◽  
Tadao Takada ◽  
Sachiko Tojo ◽  
Nobuyuki Ichinose ◽  
Tetsuro Majima
Keyword(s):  
Radical Cation ◽  
Transient Absorption ◽  
Hole Transfer

Hole transfer through DNA monitored by transient absorption of phenothiazine radical cation

2002 ◽  
Vol 43 (1) ◽  
pp. 89-91 ◽  
Author(s):  
Kiyohiko Kawai ◽  
Tadao Takada ◽  
Sachiko Tojo ◽  
Tetsuro Majima
Keyword(s):  
Radical Cation ◽  
Transient Absorption ◽  
Hole Transfer

Kinetics of Multistep Hole Transfer in DNA by Monitoring the Transient Absorption of the Pyrene Radical Cation

2003 ◽  
Vol 107 (50) ◽  
pp. 14052-14057 ◽  
Author(s):  
Tadao Takada ◽  
Kiyohiko Kawai ◽  
Sachiko Tojo ◽  
Tetsuro Majima
Keyword(s):  
Radical Cation ◽  
Transient Absorption ◽  
Hole Transfer ◽  
Kinetics Of

Erratum to “Hole transfer through DNA monitored by transient absorption of phenothiazine radical cation”

2002 ◽  
Vol 43 (12) ◽  
pp. 2321
Author(s):  
Kiyohiko Kawai ◽  
Tadao Takada ◽  
Sachiko Tojo ◽  
Tetsuro Majima
Keyword(s):  
Radical Cation ◽  
Transient Absorption ◽  
Hole Transfer

Transient Absorption Spectroscopy of the Electron Transfer Step in the Photochemically Activated Polymerizations of N-ethylcarbazole and 9-phenylcarbazole.

2021 ◽  
Author(s):  
Georgia Thornton ◽  
Ryan Phelps ◽  
Andrew Orr-Ewing
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Absorption Spectroscopy ◽  
Electron Acceptor ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Transfer Step

The polymerization of photoexcited N-ethylcarbazole (N-EC) in the presence of an electron acceptor begins with an electron transfer (ET) step to generate a radical cation of N-EC (N-EC+.). Here, the...

Near-Infrared Excitation of the peri-Xanthenoxanthene Radical Cation Drives Energy-Demanding Hole Transfer Reactions

2018 ◽  
Vol 122 (41) ◽  
pp. 23364-23370 ◽  
Author(s):  
Joseph A. Christensen ◽  
Jinyuan Zhang ◽  
Jiawang Zhou ◽  
Jordan N. Nelson ◽  
Michael R. Wasielewski
Keyword(s):  
Radical Cation ◽  
Near Infrared ◽  
Transfer Reactions ◽  
Hole Transfer ◽  
Infrared Excitation

scholarly journals Contrasting Electron and Hole Transfer Dynamics from CH(NH2)2PbI3 Perovskite Quantum Dots to Charge Transport Layers

2020 ◽  
Vol 10 (16) ◽  
pp. 5553
Author(s):  
Zhigang Lou ◽  
Shuyan Liang ◽  
Jiabei Yuan ◽  
Kang Ji ◽  
Jianyu Yuan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Charge Transport ◽  
Transient Absorption ◽  
Diffusion Length ◽  
Temporal Evolution ◽  
Fine Tuning ◽  
Transient Absorption Spectroscopy ◽  
Hole Transfer ◽  
Perovskite Quantum Dots ◽  
Hole Diffusion Length

In this work, the ultrafast transient absorption spectroscopy (TAs) was utilized to first investigate the charge transfer from the emerging FAPbI3 (FA = CH(NH2)2) perovskite quantum dots (PQDs) to charge transport layers. Specifically, we compared the TAs in pure FAPbI3 PQDs, PQDs grown with both electron and hole transfer layers (ETL and HTL), and PQDs with only ETL or HTL. The TA signals induced by photoexcited electrons decay much faster in PQDs samples with the ETL (~20 ps) compared to the pure FAPbI3 PQDs (>1 ns). These results reveal that electrons can effectively transport between coupled PQDs and transfer to the ETL (TiO2) at a time scale of 20 ps, much faster than the bimolecular charge recombination inside the PQDs (>1 ns), and the electron transfer efficiency is estimated to be close to 100%. In contrast, the temporal evolution of the TA signals in the PQDs with and without HTL exhibit negligible change, and no substantive hole transfer to the HTL (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], PTAA) occurs within 1 ns. The much slower hole transfer implies the further potential of increasing the overall photo-carrier conversion efficiency through enhancing the hole diffusion length and fine-tuning the coupling between the HTL and PQDs.

Light-induced hole transfer in a hypervalent phosphorus(V) octaethylporphyrin bearing an axially linked bis(ethylenedithio)tetrathiafulvalene

2010 ◽  
Vol 14 (02) ◽  
pp. 178-187 ◽  
Author(s):  
Prashanth K. Poddutoori ◽  
Ann Dion ◽  
Songjie Yang ◽  
Melanie Pilkington ◽  
John D. Wallis ◽  
...  
Keyword(s):  
Steady State ◽  
Fluorescence Quenching ◽  
Radical Cation ◽  
High Efficiency ◽  
Chemical Oxidation ◽  
Reference Compound ◽  
Epr Spectrum ◽  
Hole Transfer ◽  
Time Resolved ◽  
Epr Measurements

A phosphorus(V) porphyrin bearing an axially linked bis(ethylenedithio)tetrathiafulvalene, dyad 1, and its radical cation phosphorus(V) porphyrin- O-CH2 -(bis(ethylenedithio)tetrathiafulvalene)+•, dyad 2, have been synthesized and studied as an electron hole donor-acceptor system. The absorption spectrum of dyad 1 does not show evidence for electronic coupling between the porphyrin and the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) moieties. However, the steady-state fluorescence of the porphyrin chromophore is quantitatively quenched and its transient fluorescence lifetime is shortened compared to a reference compound in which the BEDT-TTF moiety is replaced by a methoxy group. Chemical oxidation of the BEDT-TTF moiety in dyad 1 to give dyad 2 results in recovery of the fluorescence intensity. This behavior suggests that the fluorescence quenching in dyad 1 is the result of intramolecular hole transfer from the the excited porphyrin to the BEDT-TTF moiety. The occurence of hole transfer in dyad 1 is confirmed by freeze-trapping and time-resolved electron paramagnetic resonance (EPR) measurements. The freeze-trapping EPR experiments show that steady-state irradiation of the complex leads to accumulation of its radical cation (dyad 2) while the transient EPR measurements at 5 °C show that flash irradiation of dyad 1 results in formation of a radical-ion pair with a lifetime of at least 300 ns. The triplet state of the porphyrin, which is formed by intersystem crossing and gives a strong transient EPR spectrum in the reference compound, is not observed for dyad 1. Together, the fluorescence quenching and the polarization pattern of the radical pair suggest that the hole transfer occurs from the excited singlet state of the porphyrin with high efficiency.

scholarly journals Photosensitized one-electron oxidation of DNA

2005 ◽  
Vol 77 (6) ◽  
pp. 963-975 ◽  
Author(s):  
Kiyohiko Kawai ◽  
Tetsuro Majima
Keyword(s):  
Dna Damage ◽  
High Performance ◽  
Transient Absorption ◽  
Basic Mechanism ◽  
Absorption Measurement ◽  
Mechanistic Study ◽  
Hole Transfer ◽  
Damage Quantification ◽  
Oxidation Of Dna ◽  
Kinetics Of

Photosensitized one-electron oxidation of DNA has attracted much interest because it causes oxidative damage which leads to mutation, and because it is involved in the basic mechanism of photodynamic therapy. In the present article, we describe the mechanistic study of photosensitized DNA damage, especially addressing the kinetics of hole transfer by adenine(A)-hopping and its effect on the DNA damage. The combination of the transient absorption measurement and DNA damage quantification by high-performance liquid chromatography clearly demonstrate that the yield of the DNA damage correlates well with the lifetime of the charge-separated state caused by A-hopping, showing that hole transfer helps DNA damage. These findings led us to propose a new method to accomplish the efficient DNA damage using a combination of two-color, two-laser irradiation.

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