Characterization and electrochemistry of interfacial self-assembled multi-manganese(III)-porphyrin arrays

Electrochemical behaviors and catalytic oxidation of nitrite have been investigated by using the indium tin oxide (ITO) electrodes modified by the Langmuir–Blodgett (LB) films of manganese porphyrin and its palladium-mediated multiporphyrin arrays. The multiporphyrin arrays were prepared at the air–water interface. Surface pressure–area isotherms indicated that monolayers of the porphyrin of MnTPyP (TPyP: tetrapyridylporphyrin) could be stabilized on the sodium tetraphenylboron and K₂PdCl₄ subphase surfaces, but not on the pure water surface. These monolayers were transferred onto quartz and ITO substrate surfaces with the use of vertical dipping method, and characterized by using transmission electron microscope, UV–vis absorption and X-ray photoelectron spectra. For the electrodes modified by the porphyrin LB films, reversible Mn^(II)TPyP ↔ Mn^(III)TPyP and Mn^(III)TPyP ↔ Mn^(IV)TPyP redox couples were recorded, and centered at about − 0.17 and 0.52 V vs. Ag/AgCl, respectively. A high-valent Mn^(V)TPyP intermediate was detected when the cyclic voltammograms were measured in an electrolyte solution containing sodium nitrite. These multiporphyrin arrays modified electrode showed very strong stability and reproductivity, resulting in potential applications in the development for the nitrite sensors and molecular catalysts of organic compounds.