| A combination of the electrochemical quartz crystal microbalance (EQCM) and molecular modeling with the extensible systematic force field, have been applied to the investigation of poly(vinylferrocene) with counterions of different sizes over extended potential ranges.; Cyclic voltammetry combined with the electrochemical quartz crystal microbalance, was used to study the current-potential and mass-potential curves of poly(vinylferrocene) in aqueous bathing solutions of different counter anions. Voltammetric characteristics such as, peak anodic potential (Epa), peak cathodic potential (Ep c), peak anodic current (ipa) and peak cathodic current (ip c) were observed to be dependent on the counter anion. A positive potential higher than 1.10 V resulted in the onset of irreversible structural and electrochemical changes in the polymer.; In an effort to understand this phenomenon at the molecular level, molecular modeling with Insight II 97, chapter 5, was used to model the equilibrium conformational states of oligomers of vinylferrocene. An initial study of the ferrocene molecule was made with respect to the interionic and steric interactions between the ferricinium cation and model monovalent anions based on group VII elements. The modeling procedure, thus developed, was extended to the modeling of doped (partially or fully oxidized) and undoped (neutral) oligomers (dimer, trimer, tetramer, 16mer) of viny1ferrocene. The results indicate that, numerous energy minima, exist, corresponding to different oligomeric structures. These energy states, depend on the assumed starting configuration and anionic species, and result from coulombic, van der Waals, bonding and non-bonding interactions between the charged ferricinium oligomer and anionic species. |
