Redox‐chemical investigations of soluble oligo(p‐phenylene)s

The chemical and electrochemical reductions of two series of oligo( p ‐phenylene)s with different substitution patterns are investigated. The resulting anionic species are characterized on the one hand using NMR spectroscopy and quenching experiments obtaining dianions in the case of terphenyls and quaterphenyls. On the other hand, cyclic voltammetric experiments were carried out with the results that compounds with substitution only in the terminal rings behave as typical conjugated oligomers, and substituents in the middle rings disturb the conjugation and alter the mechanism of electron transfer. Further, the charge distribution, the stereodynamic behaviour and the redox potentials are examined as a function of chain length and substitution. The reduction of the title compounds shows that only the substitution of terminal phenyl rings leads to suitable model compounds for the doping of poly( p ‐phenylene).