Electrochemical Synthesis and Chiroptical Properties of Optically Active Poly(o-methoxyaniline)

The electropolymerization of o -methoxyaniline in the presence of (+)-(1 S )- or (−)-(1 R )-camphorsulfonic (HCSA) provides a route to optically active poly( o -methoxyaniline) (POMA). The green emeraldine salt films POMA·(+)-HCSA ( 1a) and POMA·(−)-HCSA ( 1b ) deposited on ITO-coated glass working electrodes exhibit mirror imaged circular dichroism spectra in the visible region, indicating diastereoselection in the electrochemical deposition. Their chiroptical properties suggest that these POMA·HCSA salts adopt a “compact coil” conformation for their polymer chains. The films are readily soluble in a range of organic solvents, retaining their optical activity and “compact coil” conformations. A strong red shift in the position of the low energy polaron band of 1a along the solvent series NMP < CHCl 3 < DMSO, DMF < MeOH indicates a concomitant increase in the conjugation length of the polymer chains. The 1a and 1b films may also be dedoped in aqueous 1.0 mol dm -3 NH 4 OH to give optically active POMA emeraldine base. Redoping of these latter blue films with 1.0 mol dm -3 HCl regenerates the circular dichroism spectra of the original 1a and 1b films, confirming retention of configuration during reversible dedoping/redoping cycles in the solid state.