Electrochemical Properties of the Oxo‐Manganese‐Phenanthroline Complex Immobilized on Ion‐Exchange Polymeric Film and Its Application as Biomimetic Sensor for Sulfite Ions

A biomimetic sensor containing the oxo‐bridged dinuclear manganese‐phenanthroline complex incorporated into a cation‐exchange polymeric film deposited onto glassy carbon electrode for detection of sulfite was studied. Cyclic voltammetry at the modified electrode in universal buffer showed a two electron oxidation/reduction of the couple Mn IV (μ‐O) 2 Mn IV /Mn III (μ‐O) 2 Mn III . The sensor exhibited electrocatalytic property toward sulfite oxidation with a decrease of the overpotential of 450 mV compared with the glassy carbon electrode. A plot of the anodic current versus the sulfite concentration for potential fixed (+0.15 V vs. SCE) at the sensor was linear in the 4.99×10 −7 to 2.49×10 −6  mol L −1 concentration range and the concentration limit was 1.33×10 −7  mol L −1 . The mediated mechanism was derived by MichaelisMenten kinetics. The calculated kinetics values were MichaelisMenten rate constant= ${K{{{\rm app}\hfill \atop {\rm M}\hfill}}}$ =1.33 µmol L −1 , catalytic rate constant=6.06×10 −3  s −1 and heterogeneous electro‐chemical rate constant=3.61×10 −5  cm s −1 .