Reactivity of Superoxide Anion Radical with a Perchlorotriphenylmethyl (Trityl) Radical

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• 作者：Vijay Kumar Kutala ; Frederick A Villamena ; Govindasamy Ilangovan ; Daniel Maspoch ; Nans Roques ; Jaume Veciana ; Concepci&oacute ; Rovira ; Periannan Kuppusamy
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：January 10, 2008
• 年：2008
• 卷：112
• 期：1
• 页码：158 - 167
• 全文大小：288K
• 年卷期：v.112,no.1(January 10, 2008)
• ISSN：1520-5207

文摘

The reaction of superoxide radical with a tricarboxylate derivative of perchlorotriphenylmethyl radical (PTM-TC) is studied. PTM-TC is a stable ("inert") free radical, which gives a single sharp electron paramagneticresonance (EPR) peak in aqueous solutions. PTM-TC also gives a characteristic optical absorption at 380nm. Superoxide, on reaction with PTM-TC, induced a decrease in the intensity of the EPR signal and opticalabsorption of PTM-TC at 380 nm. The signal loss was specific to superoxide and linearly dependent on thesuperoxide flux in the system. Competitive kinetics experiments revealed that PTM-TC reacts with superoxidewith an apparent second-order rate constant of 8.3 × 10⁸ M^-1 s^-1. Electrochemical and mass spectrometricanalyses of the reaction suggested the formation of perchlorotriphenylmethane and molecular oxygen asproducts. The high sensitivity of detection of PTM-TC combined with the high rate constant of the reactionof superoxide with PTM-TC may offer a potential opportunity for measurement of superoxide in biologicalsystems. In conclusion, the PTM-TC molecule has high sensitivity and specificity for superoxide radicalsand thus may enable quantitative detection of superoxide generation in biological systems using EPR and/orspectrophotometric methods.