Potential-Driven Chirality Manifestations and Impressive Enantioselectivity by Inherently Chiral Electroactive Organic Films

The typical design of chiral electroactive materials, hinging on attaching chiral pendants to an electroactive polyconjugated backbone, generally results in modest chirality manifestations. We propose electroactive chiral polyheterocycles, where chirality is not external to the electroactive backbone but inherent to it, resulting from a tailored torsion generated by the periodical presence of atropisomeric, conjugatively active biheteroaromatic scaffolds, e.g. 3,3’-bithianaphthene. As the stereogenic element coincides with the electroactive site, films of impressive chiroptical activity and outstanding enantiodiscrimination properties are obtained. Moreover, chirality manifestations can be finely and reversibly tuned by the electric potential, as progressive injection of holes forces the two thianaphthene rings to co-planarize to favour delocalization. Such deformations, revealed by CD spectroelectrochemistry, are elastic and reversible, suggesting the image of a breathing system.