Triplet excited states and radical intermediates formed in electron pulse radiolysis of amino-substituted fluorenones |
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Authors: | Vaishali Samant Ajay K Singh Tulsi Mukherjee Dipak K Palit |
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Institution: | Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India |
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Abstract: | Electron pulse radiolysis of four differently substituted amino derivatives of fluorenone, namely, 1-amino-, 2-amino- 3-amino-, and 4-aminofluorenone, has been carried out to study the effect of structure on the spectroscopic and kinetic characteristics of the triplet excited states as well as the transient free radical intermediates formed under reducing and oxidizing conditions. The triplet states of these compounds have been generated in benzene by pulse radiolysis and in other solvents by flash photolysis technique and their spectral and kinetic properties have been investigated. Hydrated electron (eaq?) has been found to react with these fluorenone derivatives to form the anion radical species with a diffusion-controlled rate constant. The spectral and kinetic properties of the transient ketyl and anion radicals have been studied by generating them in aqueous solutions of suitable pH. The pKa values of ketyl anion radical equilibria are in the range of 6.8–7.7 for these derivatives. The oxidized species have been generated by reaction with the azide radical. Hydrogen atom adducts as well as the cation radicals of these derivatives have also been generated by pulse radiolysis and characterized. |
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Keywords: | Amino-substituted fluorenones Flash photolysis and electron pulse radiolysis Triplet states Reaction with hydrated electron Ketyl and anion radicals Hydrogen atom adduct Oxidized and cation radicals |
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