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Journal of the Electrochemical Society, Vol.162, No.3, H124-H131, 2015
Solvation of 1-Amino-4-Hydroxy-9,10-Anthraquinone Governs Its Electrochemical Behavior in Non-Aqueous and Aqueous Media: A Cyclic Voltammetry Study
The electrochemical behavior of 1-amino-4-hydroxy-9,10-anthraquinone (1-AHAQ) was studied in acetonitrile, dimethyl formamide and dimethyl sulfoxide. In such solvents 1-AHAQ undergoes successive two one-electron reduction forming semiquinone and quinone dianion respectively in which the first step is completely reversible and the second step is quasi-reversible. The reduction and oxidation potentials are dependent on the polarity of the media. The electrochemical parameters are evaluated and correlated with the polarity index of the media. During such reductions a comproportionation reaction operates between the quinone (1-AHAQ) and its dianion (1-AHAQ(2-)) to form a semiquinone radical (1-AHAQ(center dot-)). The apparent comproportionation constants are calculated to find a comparative account on the stability of the radical intermediate in such solvents. In the presence of benzoic acid the electrochemical behavior of 1-AHAQ is altered significantly which is determined in this study. Role of the polarity of the solvents, intra or intermolecular hydrogen bonding and acidic additives on the stability of the radical species is evaluated. In aqueous buffer the reduction of 1-AHAQ follows a one step two-electron process where a kinetic study was carried out to determine the apparent charge transfer rate constants at various scan rates. The results show that electrochemical behavior of 1-AHAQ in non-aqueous and aqueous media mimics the action of anthracycline anticancer drugs which may find a similarity in their biological activities at the cellular level. (C) 2014 The Electrochemical Society. All rights reserved.