The pH dependent oxidation behaviour of the ferrocene subunit in ferrocenylcarboxylic acids of formula Fc(CH2)nCOOH (n=0, 1, 2) has been investigated through differential pulse voltammetry experiments in 4:1 acetonitrile/water solutions. Different voltammetric responses have been obtained depending whether the pH has been varied through a buffer (a single peak, whose E(1/2) value decreases with the increasing pH) or through an acid-base titration (two distinct peaks, the less anodic corresponding to the oxidation of the FcCOO(-) species, the more anodic corresponding to the oxidation of the FcCOOH species, whose relative intensities vary with the pH). The electrochemically determined pK(a) values for the Fc(CH2)(n)COOH and [Fc(+)](CH2)(n)COOH forms indicate that the Fc-to-Fc(+) oxidation process makes the acidity of the proximate carboxylic group increase. Such a switching effect, electrostatic in nature, decreases as n increases

CONTROLLING THE ACIDITY OF THE CARBOXYLIC GROUP BY A FERROCENE BASED REDOX SWITCH

FABBRIZZI, LUIGI;LICCHELLI, MAURIZIO;PALLAVICINI, PIERSANDRO
1994-01-01

Abstract

The pH dependent oxidation behaviour of the ferrocene subunit in ferrocenylcarboxylic acids of formula Fc(CH2)nCOOH (n=0, 1, 2) has been investigated through differential pulse voltammetry experiments in 4:1 acetonitrile/water solutions. Different voltammetric responses have been obtained depending whether the pH has been varied through a buffer (a single peak, whose E(1/2) value decreases with the increasing pH) or through an acid-base titration (two distinct peaks, the less anodic corresponding to the oxidation of the FcCOO(-) species, the more anodic corresponding to the oxidation of the FcCOOH species, whose relative intensities vary with the pH). The electrochemically determined pK(a) values for the Fc(CH2)(n)COOH and [Fc(+)](CH2)(n)COOH forms indicate that the Fc-to-Fc(+) oxidation process makes the acidity of the proximate carboxylic group increase. Such a switching effect, electrostatic in nature, decreases as n increases
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/446155
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