A chiral recognition polymer based on polyaniline

When polyaniline is doped with either R- or S-camphorsulfonic acid (CSA) it adopts a chiral structure. Removing the chiral acid dopant leads to a new form of chiral polyaniline. Such chiral dedoped polyanilines have the ability to discriminate among enantiomers of amino acids such as DL-phenylalanine. For example, the dedoped form of R-CSA polyaniline preferentially complexes with L-phenylalanine as indicated by a “doping” type absorption observed at ~450 nm in circular dichroism spectra. Since the dedoped form of R-CSA polyaniline does trot complex with d-phenylaniline, this chiral polymer can be used to separate racemic mixtures of DL-phenylalanine. Moreover, the amino acid enantiomer bound by the chiral polyaniline can be released by an organic solvent. The chiral separation mechanism is further explored by examining the interactions of phenylalanine derivatives with the chiral dedoped polyanilines.