Elaboration of new modified electrodes (MEs) by electropolymerization of Cu(II)-Schiff base complexes bearing pyrrole moieties: Application in electroreduction of acetophenone and carbon dioxide

Abstract

Novel functional Schiff base ligands bearing pyrrole moieties in their structures, L1:1-(3-Pyrrole-1-yl-propylimino-methyl)-naphtalen-2-ol, L2:1-(3-Pyrrole-1-yl-propylimino-methyl)-phenol and L3: 1-(3-Pyrrole-1-yl-phenylimino-methyl)-naphtalen-2-ol as well as their Cu(II) complexes, have been synthesized and characterized by means of common spectroscopic analysis methods such as FTIR, UV–Vis, 1H NMR, 13C NMR, GC–MS and thermogravimetric analysis (TGA). The complexes, along with their metallic centres, were electropolymerized by the cyclic voltammetry method on platinum (Pt) and indium tin oxide (ITO) substrates, so that new and original modified electrodes (MEs) could be obtained, i.e. ME Poly(Li-Cu)Pt and ME Poly (Li-Cu)ITO (i = 1–3). MEs obtained on ITO were characterized by FTIR spectroscopy and their morphology was investigated using scanning electron microscopy (SEM) and elemental composition by EDX analysis. The catalytic activity of these modified electrodes was successfully evaluated using electroreduction reactions in aqueous media of organic substrates. The efficiently of acetophenone reduction was significantly improved by increasing the quantity of added substrate. The value of cathodic current intensity ipc goes up from 7 to 42 μA for substrate volume values varying from 0 to 40 μL, respectively. In addition, a significant increase of current values from −70 μA to 175 μA was observed in the presence of a saturated solution of CO2.