Conducting polyaniline/calixarene salts: Synthesis and properties

Emeraldine base has been doped with the sulfonated calixarene host species, calix[4]-p-tetrasulfonic and calix[6]-p-hexasulfonic acid in water or DMSO solvents, yielding novel colloidal conducting emeraldine salts PAn.calix[4]SO3H and PAn.calix[6]SO3H. The colloidal polyaniline products were characterized by W-vis and FTIR spectra, cyclic voltammetry, particle size analysis, and transmission electron microscopy. The polyelectrolyte dopants conferred enhanced stability on the emeraldine salts toward alkaline dedoping, with only partial conversion to emeraldine base occurring even at pH 14. The emeraldine salts could, however, be readily oxidized by persulfate ion at pH 2 to the pernigraniline salt forms, while oxidation at pH 12 generated pernigraniline base. Reduction at pH 12 using hydrazine hydrate yielded the fully reduced leucoemeraldine base.