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Photoinduced Electron and H-atom Transfer Reactions of Xanthone by Laser Flash Photolysis
Jin-ting Wang,Yang Pan,Li-min Zhang,Shu-qin Yu*
Author NameAffiliationE-mail
Jin-ting Wang Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China  
Yang Pan Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China  
Li-min Zhang Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China  
Shu-qin Yu* Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China sqyu@ustc.edu.cn 
Abstract:
The property of the lowest excited triplet states of xanthone in acetonitrile was investigated using time-resolved laser °ash photolysis at 355 nm. The transient absorption spectra and the quenching rate constants(kq) of the excited xanthone with several amines were determined. Good correlation between lgkq and the driving force of the reactions suggests the electron transfer mechanism, except aniline and 3-nitroaniline (3-NO2-A) which showed energy transfer mechanism. With the appearance of ketyl radical, hydrogen atom transfer also happened between xanthone and dimethyl-p-toluidine, 3,5,N,N-tetramethylaniline, N,N-dimethylaniline, and triethylamine. Therefore, both electron transfer and H-atom transfer occured in these systems. Great discrepancies of kq values were discovered in H-atom abstraction reactions for alcohols and phenols, which can be explained by di?erent abstraction mechanisms. The quenching rate constants between xanthone and alcohols correlate well with the ?-C?H bonding energy of alcohols.
Key words:  Laser °ash photolysis, Xanthone, Electron transfer, H-atom transfer
FundProject:
光诱导呫吨酮电子转移和氢转移反应的激光闪光光解研究
王金婷,潘洋,张立敏,俞书勤*
摘要:
用时间分辨激光闪光光解的方法研究了在乙腈溶剂中呫吨酮的激发三重态的性质,并得到了呫吨酮激发三重态和胺类、醇类以及酚类反应的瞬态吸收光谱和猝灭速率常数(kq).除了苯胺和3-硝基苯胺被认为是能量转移外,呫吨酮和其余胺类的反应随着自由能变的减校lgkq逐渐增大,由此认为发生了电子转移反应.而对于二甲基-对甲苯胺、3,5,N,N-四甲基苯胺、N,N-二甲基苯胺、三乙胺来说,通过瞬态吸收光谱的变化可以知道既有电子转移反应又有氢转移反应发生.呫吨酮和醇类只发生氢转移反应,其猝灭速率常数和醇的?-C?H的键能有关.由
关键词:  激光闪光光解, 呫吨酮, 电子转移, 氢转移
DOI:10.1088/1674-0068/20/04/395-400
分类号: