• J Mahadevan

      Articles written in Journal of Chemical Sciences

    • One-electron reduction of toluidine blue. A pulse radiolysis study

      J Mahadevan S N Guha K Kishore P N Moorthy

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      The technique of nanosecond pulse radiolysis has been used to study the one-electron reduction of toluidine blue. Apart from H andeaq various organic reducing radicals derived from isopropanol, tetrahydrofuran, cytosine etc. have been employed. The rate constants for the one-electron reduction was evaluated from build up traces. By monitoring the absorbance changes as a function of pH, twopKa values were obtained suggesting the existence of the species in three conjugate acid-base forms. The spectra of the different protonated forms were monitored and their characteristic features have been presented here. In the case of H-atoms it has been observed that in addition to the electron-transfer reaction, other processes like adduct formation also appear to be taking place. Using the redox titration method, with radicals of known redox potential the one-electron reduction potential of toluidine blue was also evaluated (vs. NHE).

    • One-electron oxidation of toluidine blue. A pulse radiolysis study

      J Mahadevan S N Guha K Kishore P N Moorthy

      More Details Abstract Fulltext PDF

      The one-electron oxidation of toluidine blue by specific oxidising radicals such as Cl2, Tl(II), N3, Br2 etc. has been studied by employing the pulse radiolysis technique. The Br2 radical was found to be less efficient in oxidising toluidine blue as compared to Cl2., Tl+2 and N3. The semioxidised species exhibited only onepKa indicating the presence of two conjugate acid-base forms whose spectral and kinetic features were evaluated. Reaction of OH radicals with the dye gave rise to a transient species which exhibited spectral and kinetic features different from that of the semioxidised species indicating that the mode of reaction of OH is different.

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