Pulse radiolysis study of the oxidation of the I− ions with the radical anions Br2 ·− in an aqueous solution: formation and properties of the radical anion BrI·−

2008 ◽  
Vol 57 (9) ◽  
pp. 1821-1826 ◽  
Author(s):  
B. G. Ershov ◽  
E. Janata ◽  
A. V. Gordeeva
Keyword(s):  
Aqueous Solution ◽  
Radical Anion ◽  
Pulse Radiolysis ◽  
Radical Anions ◽  
Solution Formation

Pulse radiolysis study of I− oxidation with radical anions Cl2 ⋅− in an aqueous solution

2005 ◽  
Vol 54 (6) ◽  
pp. 1378-1382 ◽  
Author(s):  
B. G. Ershov ◽  
E. Janata ◽  
A. V. Gordeeva
Keyword(s):  
Aqueous Solution ◽  
Pulse Radiolysis ◽  
Radical Anions

The one- and two-electron reduction of 2-thioriboflavin by radical anions of CO2 and dithiothreitol

1986 ◽  
Vol 64 (1) ◽  
pp. 67-70 ◽  
Author(s):  
Parminder S. Surdhar ◽  
David A. Armstrong ◽  
Vincent Massey
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Radical Anion ◽  
Pulse Radiolysis ◽  
Continuous Production ◽  
Radical Anions ◽  
Reduction Step ◽  
Equivalence Point ◽  
Electron Reduction ◽  
The One

The one- and two-electron reductions of 2-thioriboflavin with[Formula: see text] and cyclic disulphide anion of dithiothreitol [Formula: see text] have been studied by the steady state γ and pulse radiolysis techniques. The [Formula: see text] radical reacted with 2-thioriboflavin to give the neutral semiquinone (•FlH) and the radical anion (•Fl−) at pH 5 and 10 respectively. The pK of the •FlH radical was determined to be 7.4. In the case of the anion, the 2-thioriboflavin spectrum is similar in shape to that of FAD radical anion, but red shifted by 40–50 nm. Red shifts are also seen in the neutral •FlH form for the 370-nm peak and 580-nm shoulder. However, in addition, there is strong enhancement of the absorbance at 500 nm. The spectrum of 2-thioriboflavin semiquinone produced in the presence of 2–5 mM dithiothreitol was perturbed, as was observed previously for unsubstituted flavin semiquinones in the presence of sulphydryls. The rate constants for the initial one-electron reduction step viz: [Formula: see text] were 4.0 ± 0.5 × 109 M−1 s−1 and 1.3 ± 0.2 × 109 M−1 s−1 at pH 7 and 10 respectively. The corresponding rate for the reaction of [Formula: see text] with 2-thioriboflavin at pH 7 was determined to be 2.4 ± 0.2 × 109 M−1 s−l. The continuous production of [Formula: see text] radicals by γ radiolysis reduced 2-thioriboflavin to the dihydro form, and the flavin was regenerated on the addition of air. The[Formula: see text] radical also effected a two-electron reduction. However, in this case, if the process was taken beyond the equivalence point, the dihydroflavin spectrum was bleached and the oxidized flavin could not be recovered.

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