Potential-driven chirality manifestations and impressive enantioselectivity by inherently chiral electroactive organic films

The typical design of chiral electroactive materials involves attaching chiral pendants to an electroactive polyconjugated backbone and generally results in modest chirality manifestations. Discussed herein are electroactive chiral poly-heterocycles, where chirality is not external to the electroactive backbone but inherent to it, and results from a torsion generated by the periodic presence of atropisomeric, conjugatively active biheteroaromatic scaffolds, (3,3-bithianaphthene). As the stereogenic element coincides with the electroactive one, 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 favor delocalization. Such deformations, revealed by CD spectroelectrochemistry, are elastic and reversible, thus suggesting a breathing system. A jolt upon recognition: Torsion in the electroactive backbone endows poly-heterocycle films with high chiroptical activity, which is reversibly tunable by the electric potential, and outstanding enantiorecognition capability with about 100 mV between two enantiomeric ferrocenyl amino probes, in any order, in alternating sequences, and as a racemate.