Redox Behavior of a Derivative of Vitamin K at a Glassy Carbon Electrode

The redox behavior of a novel derivative of vitamin K, (E)-2-((prop-1-enyloxy)methyl)naphthalene-1,4-dione (PMND) was investigated in the pH range 1.2-12.7 by modern electrochemical techniques like cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). PMND was found to reduce in a chemically irreversible pH dependent manner. The decrease in peak current with successive scans revealed PMND and its reduction product to desorb rapidly from the electrode surface. The plot of Ep vs. pH exhibiting four linear segments provided compelling evidence of PMND reduction by different mechanistic routes in acidic, neutral and alkaline media. The pKa of PMND with values of 6.67, 8.93 and 11.3 evidenced the existence of three acid-base equilibria. The redox mechanism of PMND was proposed on the basis of voltammetric results.