Hole Transfer in DNA by Monitoring the Transient Absorption of Radical Cations of Organic Molecules Conjugated to DNA

2012 ◽  
pp. 117-137 ◽  
Author(s):  
Kiyohiko Kawai ◽  
Tetsuro Majima
Keyword(s):  
Organic Molecules ◽  
Transient Absorption ◽  
Radical Cations ◽  
Hole Transfer

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.

scholarly journals Snapshot Transient Absorption Spectroscopy of Carotenoid Radical Cations in High-Light-Acclimating Thylakoid Membranes

2017 ◽  
Vol 8 (22) ◽  
pp. 5548-5554 ◽  
Author(s):  
Soomin Park ◽  
Alexandra L. Fischer ◽  
Zhirong Li ◽  
Roberto Bassi ◽  
Krishna K. Niyogi ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Radical Cations ◽  
Thylakoid Membranes ◽  
High Light ◽  
Transient Absorption Spectroscopy

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.

scholarly journals Hole-Mediated PhotoRedox Catalysis: Tris(p-Substituted)biarylaminium Radical Cations as Tunable, Precomplexing and Potent Photooxidants

2020 ◽  
Author(s):  
Shangze Wu ◽  
Jonas Zurauskas ◽  
Michal Domanski ◽  
Patrick Hitzfeld ◽  
Valeria Butera ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Excited State ◽  
Excited States ◽  
Organic Molecules ◽  
Radical Cations ◽  
Single Electron Transfer ◽  
Photoredox Catalysis ◽  
Small Organic Molecules ◽  
Fundamental Limitations ◽  
Ion Species

<p>Electrochemically-mediated Photoredox Catalysis emerged as a powerful synthetic technique in recent years, overcoming fundamental limitations of electrochemistry and photoredox catalysis in the single electron transfer activation of small organic molecules. However, the mechanism of how photoexcited radical ion species with ultrashort (picosecond-order) lifetimes could ever undergo productive photochemistry has eluded synthetic chemists. We report tri(<i>para</i>-substituted)biarylamines as a tunable class of electroactivated photocatalysts that become superoxidants in their photoexcited states, even able to oxidize molecules (such as dichlorobenzene and trifluorotoluene) beyond the solvent window limits of cyclic voltammetry. Furthermore, we demonstrate that precomplexation not only permits the excited state photochemistry of tris(<i>para</i>-substituted)biarylaminium cations, but enables and rationalizes the surprising photochemistry of their <i>higher-order</i> doublet (D<i><sub>n</sub></i>) excited states.</p>

Positive hole transfer between organic molecules of different classes in freon matrices

2007 ◽  
Vol 41 (6) ◽  
pp. 409-414 ◽  
Author(s):  
A. V. Egorov ◽  
I. A. Baranova ◽  
A. A. Zezin ◽  
A. A. Andriyanova ◽  
V. I. Feldman
Keyword(s):  
Organic Molecules ◽  
Hole Transfer ◽  
Positive Hole

scholarly journals Triplet 1-Nitronaphthalene and Competitive Energy and Electron Transfer Reactions With Trans-Stilbene

1999 ◽  
Vol 19 (1-4) ◽  
pp. 397-401
Author(s):  
T. Fournier ◽  
G. D. Scholes ◽  
I. R. Gould ◽  
S. M. Tavender ◽  
D. Phillips ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Transient Absorption ◽  
Radical Cations ◽  
Time Resolved ◽  
Polar Solution ◽  
Trans Stilbene ◽  
Energy And Electron Transfer ◽  
High Concentrations ◽  
Dimer Radical Cation

A time resolved resonance Raman (TR3) study of 1-nitronaphthalene (1NN) first triplet excited state in various solvents is combined with ab initio calculations to determine the nature and the geometry of this state in environments of different polarity. A transient absorption and TR3 study of the reactions of triplet 1NN with trans-stilbene (tS) in solution in both non-polar and polar solvents is reported. In polar solution, 31NN acts as an electron acceptor whereas in non-polar solution only energy transfer to tS is observed. Moreover, at high concentrations of tS, the radical cation tS+ reacts with ground-state tS to form a dimer radical cation (tS2)+. Differences between the Raman spectra of the monomeric and the dimeric radical cations are reported in the 1500–1650 cm-1 region. The switch from energy to electron transfer when going from nonpolar to polar solutions is discussed in terms of the Marcus-Hush theory of electron transfer.

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