Electronic structure of oligoaniline doped by inorganic and organic acids

The electronic structure of doped-oligoaniline with various dopants is investigated by means of DFT method. After doping by hydrochloric acid (HCl) and camphorsulfonic acid (HCSA), the alternation of bond-lengths is decreased and the co-planarity of adjacent aromatic rings is increased. The π-conjugating effect is increased in the electronic nature of Ph-N system because the electrons can be delocalized along the backbone of oligoaniline where the hydrogen bonds as a bridge transfer the electrons. The electronic structure of polaron and bipolaron conformation and their relative stability is discussed, indicating that the preferable conformation is dependant on various dopants. The calculation results reveal that there is a relatively stronger interaction between the organic dopant of HCSA and N atoms of PANI, and more charge transfer between PANI and HCSA is a reason for the fact that the conductivity of HCSA-doped PANI is higher than that of HCl-doped PANI. The doping mechanism is proposed based on the calculation results. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008