Electrochemical and Spectroelectrochemical Study of N-hydroxyphthalimide at Poly(4-vinylpyridine) Coated Electrodes

Electrodes coated with poly(4-vinylpyridine) (PVP) shift the oxidation peak potential of N-hydroxyphthalimide (NHPI) in acetonitrile to a less positive direction compared with that at the uncoated electrodes, which promotes proton-coupled electron transfer reaction. Adding a trace amount of poly(acrylic acid) to acetonitrile stabilizes the oxidation products at the electrodes. The formed products were identified to be N-oxyl radical from thin-layer spectroelectrochemical measurements using optically transparent PVP-coated Pt minigrid electrodes. The formal redox potential of the NHPI oxidation at the PVP-coated electrodes was evaluated by Nernstian analysis of the electronic absorption spectra after the higher-order derivative conversion.