Evaluation of Ferryl Formation by Electrocatalytic Oxidation of Alkeneusing Luminol Chemiluminescence

Electrochemical formation of ferryl porphyrin was examined by electrocatalytic oxidation of alkene by measuring luminol chemiluminescence using a flow-injection method. Emission was observed both below the reduction potential of FeIIITMPyP (－0.08V at pH 11, -0.02 V at pH 7 and 0.15 V at pH 3)and above the oxidation potential(0.6 V at pH 11, 0.75 V at pH 7 and 1.1 V at pH 3). However, both anodic and cathodic emissions were inhibited significantly by the addition of alkene (cyclopent-2-ene-1-acetic acid)solutions downstream of the working electrode. Further, the spectra at both anodic and cathodic sides shifted to the longer wavelength (＞424 nm) compared to the original spectrum of FeIIITMPyP (422 nm), which was not observed with the addition of alkene solution. Therefore, the results suggest that the electrochemically generated oxo-ferryl species have been engaged in catalytic oxidation of alkene before the flow reaches the observation cell.