Emission from Charge Recombination between Radical Cations and Radical Anions of 9-Cyano-10-(p-substituted Phenyl)Anthracene Generated during Pulse Radiolysis
Journal
Journal of the Chinese Chemical Society
Journal Volume
53
Journal Issue
6
Pages
1225-1234
Date Issued
2006
Date
2006
Author(s)
Samori, Shingo
Tojo, Sachiko
Fujitsuka, Mamoru
Lin, Jui-Hsien
Ho, Tong-Ing
Majima, Tetsuro
URI
Abstract
Abstract Emission from charge recombination between radical cations and anions of 9?cyano?10?( p ?substituted phenyl)anthracenes (RA, where R is 10? p ?substituted phenyl: R = Phenyl (PA), anisyl (OA), p ? N , N ?dimethylaminophenyl (NA), N , N ?di? p ?anisylaminophenyl (DA)), as donor?acceptor type molecules, generated during the pulse radiolysis in benzene was measured together with the transient absorption of RA radical cations (RA �E+ ) and anions (RA �E? ). Based on the transient absorption and density functional theory (DFT?B3LYP/6?31G*) calculation, a twisted geometry is assumed for all RA in the ground state, RA �E+ , and RA �E? . It is suggested that the positive charge of PA �E+ , OA �E+ , and NA �E+ is delocalized on two moieties, and that of DA �E+ is localized on the donor N , N ?di? p ?anisylaminophenyl moiety, while the negative charge of all RA �E? is mainly on the acceptor 9?(10?cyano)anthracenyl moiety. When both RA �E+ and RA �E? are generated with sufficiently high concentrations during the pulse radiolysis in benzene, the charge recombination between RA �E+ and RA �E? occurred to give RA in the singlet excited state ( 1 RA*) as the emissive species, but not the excimers because of the twisted geometries of RA �E+ and RA �E? with the large torsional angles between the 9?(10?cyano)anthracenyl and p ?substituted phenyl moieties. Not only the fluorescence quantum yield of 1 RA* but also the energy differences between the annihilation enthalpy change and the excitation energy of 1 RA* are important factors for the radiolysis induced emission intensity of RA in benzene.
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Type
journal article
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