Spin-Delocalization in Charged States of para-Phenylene-Linked Dendritic Oligoarylamines

Two kinds of basic dendritic (or starburst) all- para -phenylene-linked oligotriarylamines, which are generated from para -phenylenediamine and triphenylamine as core units, respectively, were prepared, and the electrochemical, spectroelectrochemical, ESR spectroscopic measurements were carried out with respect to their application as hole transport materials in optoelectronic devices such as organic light-emitting devices. The prepared dendritic oligoarylamines exhibits the multiredox-active properirs, and are stably oxidizable up to tetra- or hexacations. According to the degree of oxidation, it was suggested that the charge distribution of the charged states gradually change so as to reduce the electrostatic repulsion between increased charges on the basis of the spectroelectrochemical studies. Moreover, the stability of the generated radical cations and the spin distribution in their radical cations were confirmed by the ESR measurements.