Aniline dimers and trimers as model compounds for polyaniline: steric control of charge separation properties

The photophysical properties of several derivatives of 4-aminodiphenylamine (ADPA), model compounds of aniline dimers and trimers are investigated. Several compounds show dual fluorescence with a charge transfer (CT) component with a significantly reduced fluorescence rate constant which can be suppressed by bridging and enhanced by sterically hindering substituents, in close similarity to the compounds showing twisted intramolecular charge transfer (TICT). The relation to polyaniline (PANI) conductivity is also discussed.