Properties of Optically Active PPys

The first reported circular dichroism (CD) study of chiral PPy s was by Delabouglise and Gamier105 on the polymers 4 (R = CH2OH, CHMc2, and Ph), in which a series of amino acids are covalently bound at the 3-position of each pyrrole ring. They exhibit a CD band at ca. 470 nm associated with the absorption band at 460 nm. This optical activity is believed to be induced by the presence of the chiral amino acid substituents, leading to the adoption of a one-handed helical structure by the PPy chains. 

Very significantly, recent studies by Pleus and coworkers108 have revealed that the conducting films 5 and 6 may be employed as chiral electrodes for the enantioselec-tive electroreduction of acetophenone and 4-methylbenzophenone in DMF to their corresponding alcohols, using DMF/LiBr as electrolyte and phenol as the proton donor. The nature of the electrolyte used for electrodeposition of the polymers influenced the optical purity of the chiral alcohol products obtained with enantioselec-tivities as high as 58% being achieved. 

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