Synthesis, characterization and electrochemical polymerization of eight transition-metal complexes of 5-amino-1,10-phenanthroline

Abstract

The ability to prepare polymer films on the surface of glassy carbon electrodes (GCEs) by electrochemical polymerization of transition-metal complexes of 5-amino-1,10-phenanthroline (aphen) was investigated. Eight different metal ions (Mn ^II , Fe ^II , Co ^II , Ni ^II , Cu ^II , Zn ^II , Ru ^II and Os ^II ) were studied. A simple and rapid method for the synthesis of the complexes with Mn ^II , Co ^II , Ni ^II , Cu ^II and Zn ^II was also elaborated. The surface coverage obtained through electrochemical polymerization of the complexes on the GCEs can be related to the redox potential of the metal. The iron(II) and ruthenium(II) complexes generated the greatest polymer film surface coverages (≈10 ^-8 mol cm ^-2 ), followed by the osmium(II) and cobalt(II) complexes (≈10 ^-9 mol cm ^-2 ). Electrochemical polymerization studies with aphen, 5-nitro-1,10-phenanthroline (nphen) and the metal complex [Fe(nphen) ₃ ] ²⁺ provided further evidence that the oxidative electropolymerization mechanism for these complexes is initiated by sweeping through the oxidative potential of the aphen ligand (+1.35 V vs. Ag–AgCl).