Optically active polyaniline derivatives prepared by electron acceptor in organic system: Chiroptical properties

A novel synthetic process was developed to yield optically active polyaniline derivatives (PANIs) prepared by electron acceptor, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), using either (+)- or (-)-camphorsulfonic acid (CSA) as the chiral inductor in organic media. Either thin films of PANIs/(+)-CSA and PANIs/(-)-CSA or their solutions exhibit mirror-imaged circular dichroism (CD) spectra in the visible region, indicating diastereoselection in the electron-transfer polymerization in the presence of chiral inductor. The films were confirmed to remain their chiral configuration during reversible dedoping/ redoping cycles in solid state, Unique chiroptical properties of PANIs/(+)- or (-)-CSA dissolved in m-cresol indicate that there exists a solvent effect on the PANIs' chain conformations and subsequent chiroptical properties, and the solvent effect is strongly dependent upon the structure of parent monomer and nature of various organic solvents. The PANIs' chain conformation in m-cresol solution forms during the dissolution, and it can be hardly changed by postintroduction of a little amount of another solvent due to the stable interactions among polymer backbone, CSA, and m-cresol for maintaining optical activity. However, PMOA doped with the same one-hand CSA can appear in the inverse CD spectrum when dissolved in cosolvent of m-cresol and DMSO at various volume ratios.