Electrochemical Properties As A Function of Ph for the Benzotriazine DI-N-Oxides
| Autor: | David I. Edwards, Narinder S. Virk, Joanne H. Tocher |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Radiation-Sensitizing Agents
Triazines Reducing agent Inorganic chemistry Antineoplastic Agents Hydrogen-Ion Concentration Electrochemistry Biochemistry Redox chemistry.chemical_compound chemistry Electron affinity Redox active Cyclic voltammetry Oxidation-Reduction Tirapazamine Function (biology) Triazine |
| Zdroj: | Free Radical Research Communications. 10:295-302 |
| ISSN: | 8755-0199 |
| Popis: | The electrochemistry of five benzotriazine di-N-oxides has been examined by cyclic voltammetry and differential pulse and dc polarographies as a function of pH. Between the pH range 8.5 and 2 the trend to less negative potentials with lowering of pH can be described by an equation of the type Ep = -apH + b. Comparison has been made with the mono- and zero-N-oxides which were found to show virtually identical trends in electron affinity with pH. The general electrochemical characteristics for the di- and mono-N-oxides under acidic conditions were found to be comparable with the zero-N-oxide. This was particularly the case on repeat scanning in the cyclic voltammetric mode. The redox mechanism involved reduction by a 4-electron addition step and subsequent loss of the N-oxide group(s) yielding the intact benzotriazine heterocycle. The heterocycle was also redox active, involving a reversible 2-electron reduction. For the di-N-oxides these two stages could be identified as separate processes at alkaline pH, but only a single step at acidic values. The mono-N-oxide in which the electrochemical behaviour was dominated by the triazine, showed only a single reduction step, although the single N-oxide group was redox active. |
| Databáze: | OpenAIRE |
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