Electrochemical studies with dissolved and surface-confined forms of neo-pentyl-ferrocene-based polyesters utilising [NBu4][B(C6F5)4] and other electrolytes.

Abstract  The voltammetric oxidation at a glassy carbon electrode of a series of ferrocenyl polyesters PmF{X}, (X=T, terephthalate; N, 2,6-naphthalene dicarboxylate; B, 4,4′-biphenyl dicarboxylate) is reported in the weakly donating and low-polarity CH2Cl2 solvent containing [NBu4][PF6], [NBu4][B(C6F5)4], or 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([bmpyr][TFSA]) as the supporting electrolyte. The one electron oxidation of the ferrocenyl groups is strongly influenced by the nature of the supporting electrolyte anion. Use of the conventional [PF6]− anion or the room temperature ionic liquid (RTIL), [bmpyr][TFSA] as the supporting electrolyte, gives rise to significant oxidation product interaction (precipitation and/or adsorption) with the electrode surface. In marked contrast, diffusion-controlled, chemically and electrochemically reversible processes are observed when the weakly coordinating [B(C6F5)4]− is used as the anionic component of the supporting electrolyte. In this case, data obtained via cyclic voltammetry, chronoamperometry and chronocoulometry are consistent with ideal reversible one electron oxidation processes and a soluble cationic product. Diffusion coefficients of the monomers, polymers, ferrocene and decamethyferrocene are reported in the CH2Cl2/[NBu4][B(C6F5)4] system. Importantly, reversible potentials that are easily obtained under these conditions show that the acyl or methyl linkers, through which the ferrocenyl group is attached to the neo-pentylenediol component, tune the redox properties of the polymers. Electrochemical studies with a glassy carbon electrode modified with microcrystals of the PmFT polymer conducted in aqueous (with KCl supporting electrolyte) or neat ionic liquid ([bmpyr][TFSA]) media also are reported. Different mechanisms apply in each of these cases. [ABSTRACT FROM AUTHOR]