title: Electrochemically induced reversible and irreversible coupling of triarylamines.
abstract: The electrochemical coupling and dimerization behavior of the low molecular compounds triphenylamine (TPA) and 9-phenylcarbazole (PHC) in comparison to tri-p-tolylamine (p-TTA) with para-blocked methyl groups has been investigated in detail. In contrast to the unsubstituted radical cations of TPA and PHC, the radical cations of p-TTA are stable in the radical cation state and do not undergo any further coupling reactions. However, we found that the dicationic state of p-TTA does undergo two different competitive reaction pathways: (1) an irreversible intramolecular coupling reaction which leads to phenylcarbazole moieties and (2) a reversible intermolecular dimerization leading to charged σ-dimers. The σ-dimers become decomposed upon discharging at low potentials (E(pc) = -0.97 V vs Fc/Fc(+)) so that the starting monomer p-TTA is partially regenerated. In particular, the reversible dimerization reaction has not been described in literature so far. Polymeric systems containing para-methyl blocked triarylamines in the side chain exhibit similar coupling behavior upon electrochemical doping.
authors.affiliation: Freiburg Institute for Advanced Studies & Institut für Makromolekulare Chemie, Universität Freiburg, Freiburg, Germany.
authors.forename: Olena
authors.initials: O
authors.lastname: Yurchenko
authors.forename: David
authors.initials: D
authors.lastname: Freytag
authors.forename: Lisa
authors.initials: L
authors.lastname: zur Borg
authors.forename: Rudolf
authors.initials: R
authors.lastname: Zentel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Heinze
authors.forename: Sabine
authors.initials: S
authors.lastname: Ludwigs