New pyridinium conjugated ferrocenes: Synthesis and electrochemical properties

New systems consisting in ferrocenes conjugated with a pyridinium core have been synthesized, and their electrochemistry has been studied in a conventional electrolyte. All ferrocenes exhibit a reversible wave as expected, however the pyridinium reduction was somewhat surprisingly found only weakly reversible, enough however to allow comparison of the number of electrons transferred between the anodic and cathodic process. All compounds give single oxidation waves with 2 or 3 electrons exchanged depending on the number of ferrocenes. An attempt to draw diffusion coefficients from the analysis of the variation of peak currents vs. scan rate has been made, showing that 2-branch compounds diffuse slightly faster than 3-branch ones. However, the differences between the two series is less than one could predict from calculation with sphere-like and rod-like molecules.