Electrochemical behaviour of interaction between Fe2+ with bisbipyridyl ligands in CH3CN. Application to an easy electrochemical procedure for tailoring films of Fe(bpy)32+ like cores (bpy = 2,2′-bipyridine)

Abstract

A simple electrochemical procedure to tailor very robust thin films containing the Fe(bpy)₃²⁺-like core (bpy = 2,2′-bipyridine) has been described. The procedure is based on the electroreductive precipitation of soluble macromolecules prepared in situ by simply mixing Fe²⁺ ions as the perchlorate salt and alkyl bridged bis-bipyridyl ligands Ln (n = 2, 4, 6) in CH₃CN. NMR analyses have shown that this solution contains mainly oligomeric species but also a small amount (∼5%) of low weight dinuclear [Fe₂^II(Ln)₃]⁴⁺ complex. The poor solubility of the reduced forms of the oligomers causes precipitation and adsorption on the electrode surface of thin films. These films exhibit an excellent stability especially when they are cycled over the iron oxidation redox system (less than 5% loss after 80 subsequent scans). This is due to the very slow redissolution of the oxidized films.