| One of the most important challenges facing the pharmaceutical industry is the simple and convenient separation of a racemic mixture of chiral molecules into individual enantiomers. Over two thirds of the drugs being developed today are chiral and often only one stereoisomer is useful, while the other may be inactive or have deleterious side effects. Most methods currently used for separating enantiomers are either inefficient or require expensive chiral starting materials. In this dissertation a novel process for producing an inexpensive conjugated chiral recognition polymer was developed.; By using the simple acid/base doping/dedoping chemistry of polyaniline, chiral dopants such as R- and S-camphorsulfonic acids can be uniformly distributed throughout the polymer on a molecular level and then removed. The key concept is that the chiral structure induced by the dopants is retained when the dopants are removed, creating the chiral recognition sites. This novel chiral form of polyaniline displayed a high chiral discrimination of enantiomers of amino acids, such as DL-phenylalanine. When deposited on supports such as silica gel, chiral polyaniline can be employed in chromatography columns to separate racemic mixtures of amino acids, such as phenylalanine, and pharmaceuticals, such as amphetamine and dopa. It is possible to tune the chiral polymer chain conformation with different chiral dopants, such as DL-dibenzoyltartaric acid. This new class of materials opens up the possibility of using polyaniline to separate enantiomers of pharmaceuticals.; As one of the oldest synthetic polymers, polyaniline has been studied extensively in the past two decades. However, the research on optically active polyaniline is very limited. In this dissertation optically active doped and dedoped polyanilines were synthesized from achiral monomers. UV and CD (circular dichroism) spectroscopy were used to systematically characterize the structure and chirality of the polymer. A study of thermal stability of the chirality was completed using TGA, DSC and CD measured as function of temperature. Free-standing films of chiral doped polyaniline were also studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Chiral dedoped polyaniline possesses a remarkable memory effect for the chirality induced by a chiral dopant. The original chirality can simply be restored by any strong acid.; Langmuir-Blodgett (LB) films of optically active polyaniline were prepared by spreading R-camphorsulfonic acid doped polyaniline N-methyl-pyrrolidinone solution onto an aqueous acid subphase using a Langmuir trough. The chirality of the LB film was induced by redoping the film with R-camphorsulfonic acid aqueous solution. This optically active polyaniline monolayer film may have potential applications for chiral sensors. |
