Photoinduced electron-transfer quenching of excited singlet states of polycyclic aromatic hydrocarbons by organic acceptors

1995 ◽  
Vol 91 (8) ◽  
pp. 1197 ◽  
Author(s):  
Graciela P. Zanini ◽  
Hern�n A. Montejano ◽  
Carlos M. Previtali
Keyword(s):  
Electron Transfer ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Photoinduced Electron Transfer ◽  
Excited Singlet ◽  
Singlet States ◽  
Polycyclic Aromatic ◽  
Excited Singlet States

Electron transfer in biologically important systems: Polycyclic aromatic hydrocarbons, DNA bases and free radicals

2018 ◽  
Vol 17 (01) ◽  
pp. 1850008
Author(s):  
M. K. Tiwari ◽  
P. C. Mishra
Keyword(s):  
Electron Transfer ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Free Radicals ◽  
Aromatic Hydrocarbons ◽  
Polarizable Continuum Model ◽  
Dna Bases ◽  
Free Energies ◽  
Species Barrier ◽  
Polycyclic Aromatic ◽  
Polarizable Continuum

Occurrence of electron transfer was studied for different combinations of polycyclic aromatic hydrocarbons (PAHs) and DNA bases as electron donors or acceptors and free radicals only as electron acceptors. Geometries of all the molecules and radicals were optimized in aqueous medium employing the polarizable continuum model. Single electron transfer (SET) and sequential proton loss electron transfer mechanisms were investigated employing Gibbs free energies of the appropriate neutral, anionic and cationic species. Barrier energies involved in these phenomena were calculated using the Marcus theory. The SET barrier energies were found to be linearly correlated with [Formula: see text] (Electron affinities of acceptors – Ionization potentials of donors). SET barrier energies from the DNA bases to the PAHs follow the order Cy [Formula: see text] Th [Formula: see text] Ad [Formula: see text] Gu, whereas SET barrier energies from the PAHs to the DNA bases follow the order Gu [Formula: see text] Ad [Formula: see text] Th [Formula: see text] Cy. Thus, guanine, among the DNA bases, is the best electron donor to the PAHs and worst electron acceptor from the same.

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