PULSE-RADIOLYSIS STUDY OF REDOX REACTIONS OF SAFRANINE-T IN AQUEOUS-SOLUTIONS - ONE ELECTRON OXIDATION

One electron oxidation of safranine T by specific oxidizing radicals such as Cl2-, Tl2+, Tl(OH)+, N3., Br2- etc. has been studied using the nanosecond pulse radiolysis technique. Reaction of free Br. atom has also been investigated at neutral pH. The semioxidized safranine species formed by these reactions have been shown to exist in two conjugate acid-base forms with pK(a) = 4.0. Their spectral and kinetic parameters have been evaluated. Using N3./N3- and I2-/2I- as reference couples, the one electron reduction potential of the semioxidized safranine has been determined to be 1.13 +/- 0.02 V vs NHE. The absorption spectra, second order decay rate constant and the pK(a) of the OH-reaction product revealed features quite different from that of the semioxidized species suggesting that the mode of OH reaction is not via electron abstraction.