Corresponding Author

Bao-kang JIN(bkjinhf@aliyun.com)


The electrochemical reduction of emodin (Q) has been investigated in acetonitrile by cyclic voltammetry (CV), IR spectroelectrochemistry cyclic voltabsorptometry (CVA) and derivative cyclic voltabsorptometry (DCVA) techniques. It was found that anion radical Q•− interacted with neutral Q to form dimer Q2•− which was further reduced to Q22− at more negative potentials. A two-step one-electron process involving electrochemical reductions of Q22− to form Q23− in the first step and Q24− in the second step, corresponding to the two cathodic peaks of C3 and C4 in CV curves was confirmed. When the scan range was between 1.0 and -2.0 V, there were two new anodic peaks (A1, A2) formed at more positive potentials. When the scan range was 0.3~-1.4 V, the current value of A2 increased with the added scan cycles, indicating that Q2•− accumulated in the solution. The C1 and C2 peaks still appeared in the second and third scans in CV curves under the consecutive scans from 1.0 to -2.0 V, suggesting the regainer of Q after each potential cycle. And Q2•− would be oxidized to Q at the potential corresponding to A1. As a result, the electrochemical redox mechanism of emodin has been proposed.

Graphical Abstract


emodin, dimerization, in situ FT–IR spectroelectrochemistry, cyclic voltabsorptometry (CVA), derivative cyclic voltaborptometry (DCVA)

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