Influence of the chiral dopant anion on the generation of induced optical activity in polyanilines

Emeraldine base (EB) is doped with (1S)-(+)-3-bromocamphor-10-sulfonic acid and a novel chiral acrylamidesulfonic acid (4) in NMP and DMF solvents to give new optically active polyaniline salts (PAn.HA). The conjugate base anions (A-) of these chiral dopants (as with the previously studied (+)-camphor-10-sulfonic acid, HCSA) contain SO-3 and carbonyl (C=O) groups that may maintain the polyaniline chains in a preferred one-sense helical screw via simultaneous electrostatic and H-bonding. Optically active polyaniline salts are also produced via analogous doping of EB (in NMP or DMF) with the chiral dicarboxylic acids (+)- or (-)-tartaric acid and O.O′-dibenzoyl-n-tartaric acid, which possess quite different structural motifs to HCSA. A common feature of all the dopants successful in generating optically active polyaniline salts is their bidental nature, allowing attachment of the dopant to the polymer backbone at two places simultaneously. © 1997 Elsevier Science Ltd.