Inherently Chiral Organic Semiconductors

The availability of materials coupling electroactivity with enantiorecognition capability is an ambitious objective of the modern research. Chirality is generally introduced in polyconjugated electroactive materials by attaching chiral pendants, invariably characterized by the presence of carbon stereocenters, to the conjugated backbone through suitable linkers. Our research is focused to develop a new class of chiral polyheterocycles, where chirality is not external to the electroactive backbone, but inherent to it and results from a tailored torsion produced by a periodical presence of atropisomeric biheteroaromatic scaffolds. The stereogenic core is tailored so as to conjugatively interconnect the two bithiophene termini and the C2 symmetry of the monomers assures the perfect constitutional regularity of the resulting polymers. The monomers synthesized on large scale so far are characterized by the atropisomeric scaffold of the 3,3’-bithianaphtene. In this communication the synthesis and the resolution of the first member of the series 1a and monomers 1b and 1c, specifically designed in order to obtain soluble and easily processable polymers will be presented. The optical, the chiroptical and the photophysical properties of these monomers and of the corresponding polymers will be discussed.