Lewis acid doped polyaniline: Preparation and spectroscopic characterization

It is demonstrated that polyaniline can be solubilized in nitromethane via complexation with SnCl4. The solutions of PANI-SnCl4 complex show UV-vis-NI R spectral features distinctly different from those reported for Bronsted a cid doped PANI, The removal of the solvent results in the formation of a fr ee-standing film of SnCl4-doped PANI, The solid-state complex shows the sto ichiometry of PANI(SnCl4)1.0(CH3NO2)(1.0), which means that both types of p olyaniline nitrogens (imine and amine) participate in the complexation reac tion and one solvent molecule is introduced in the polymer matrix per one L ewis acid molecule. Mossbauer parameters of the complex (IS = 0.43 mm/s vs SnO2, QS = 0.49 mm/s) are consistent with hexacoordinated Sn(IV) in an envi ronment of nonequivalent ligands. XPS studies are in good agreement with Mo ssbauer spectroscopy, giving Sn3d XP spectra characteristic of SnCl4. 2L co mplexes. Similar complexation can be achieved in dried PANI-(HCl)0.5; howev er, in this case, SnCl4 is complexed only on nonprotonated nitrogen sites.