Layer-by-Layer Self-Assembled Ultrathin Multilayer Film of a Lanthanide Polyoxometalate and a Bipolar Ferrocenyl Derivative

Abstract

The electrostatic layer-by-layer self-assembled multilayer films were successfully prepared from alternating deposition of K13[Nd(SiW9Mo2O39)2]·25H2O and a bipolar ferrocenyl derivative (Fc) on quartz, optical glass and indium-tin-oxide coated glass substrates. The films were investigated by UV−visible and X-ray photoelectron spectroscopies (XPS), and cyclic voltammetry. The UV−vis spectra demonstrated that the deposition of the films was uniform and reproducible. XPS revealed that the film was of chemical composition of [Nd(SiW9Mo2O39)2]13-:Fc = 1:6. The dependence of cyclic voltammograms of the film on the potential scan rates showed a redox couple with a formal potential Ef (Ef = (Epa+Epc)/2) of 0.36 V which is similar to that (0.31 V) for Fc aqueous solution, and the redox reaction for the film was surface confined.