Combined XAS/SAXS/Electrochemical studies on the conformation of poly(vinylferrocene) under redox conditions

Abstract

Metal-organic ligand complexes are important to many processes, ranging from the formation of supramolecular assemblies to electrochemical processes. Poly(vinylferrocene), PVF, is an example of a metal-organic polymer that contains localised sites which may be oxidised and reduced. Combined XAS (X-ray Absorption Spectroscopy)/SAXS (Small Angle X-ray Scattering) and electrochemical studies on PVF films in aqueous solution of 0.10 M LiClO4 and in non-aqueous solution of propylene carbonate/0.25 M TBABF4 have been carried out. The change in the oxidation Fe2+/Fe3+state of the PVF film was observed by analysing the near edge region of the XAS spectrum. The local environment around the Fe-centres of the oxidised/reduced films (from the extended region of the XAS spectrum) indicates an increase/reduction of ligand distances during the oxidation and reduction of the film. The SAXS results correlate well with the findings from XAS. The scattering profiles at very low angles are consistent with an expansion/contraction of the overall size of polymer chains upon oxidation/reduction.