Synthesis and electrochemical behavior of linear oligo(ferrocenylsilane) and hyperbranched poly(ferrocenylsilane)

Linear oligo(ferrocenylsilane) and hyperbranched poly(ferrocenylsilane) (LOFS and HPFS) were synthesized by polycondensation of 1,1′‐dilithioferrocene (FcLi₂) with dimethyldichlorosilane (Me₂SiCl₂) and FcLi₂ with methyltrichlorosilane (MeSiCl₃) in THF under different conditions, respectively. The electrochemical behaviors of LOFS and HPFS in different solvents, such as THF, CH₂Cl₂, and CHCl₃, were investigated systematically by means of cyclic voltammetry (CV). The influences of the solvent, structure of polymer, and scan rate on electrochemical behavior of poly(ferrocenylsilane) solutions are discussed. It is found that ΔE_1/2 decreases with the fall of solvent polarity apart from the solvent donor effect and increases with the increase of the acceptor number (AN) of the solvent. More interestingly, the structure of polymer imposes greatly on the interaction between ferrocene units. According to the result, the mechanism of stepwise oxidation of the ferrocene units was proposed, that is, the different conformations of polymers, attaching to electrode surface, before and after oxidized resulted in the stepwise oxidation of ferrocene groups along a chain. Kinetic parameters from CVs indicate that the electrode processes are controlled by both the electrode reaction and mass diffusion and the electrochemical irreversibility of poly(ferrocenylsilane) solutions may be ascribed to the lower electron exchange efficiency on the electrode surface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2880–2889, 2007