Electrochimica Acta, Vol.54, No.26, 6184-6189, 2009
Electrochemical investigations of antioxidant interactions with radical anion and dianion of 1,3-dinitrobenzene
Interactions of five antioxidants(AO), quercetin (Q), morin (M), rutin(R), ascorbic acid (AA) and beta-carotene (beta-C) with anion radical and dianion of 1,3-dinitrobenzene (1,3-DNB) in two aprotic solvents - dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) -have been studied by cyclic voltammetry using glassy carbon electrode. Electrochemical parameters - peak potential (E-p), half-wave potential (E-1/2), and peak current (i(p)) - for the reduction of 1,3-DNB before and after the addition of various concentrations of antioxidants, were evaluated. A gradual decrease in the oxidation peak current and finally irreversibility in 1,3-DNB radical anion and dianion systems upon the addition of antioxidant, reveals their interactions. The homogeneous bi-molecular rate constant (k(2)) Was determined from electrochemical data. In comparison to all other antioxidants used, enhanced homogeneous second order rate constant for the interaction of morin with 1,3-DNB anion radical and dianion, was observed. This aspect is attributable to protonation initiated by hydrogen bonding and greater acidic nature of morin. (C) 2009 Elsevier Ltd. All rights reserved.
Keywords:Antioxidants;Cyclic voltammetry;1,3-Dinitrobenzene;Homogeneous bi-molecular rate constant;Scavenging trends