Circularly Polarized Luminescence from Benzodithiophene and Indacenodithiophene Oligomers Alternated with Helicenes as Chiral Inducers

Chiral oligomers based on benzodithiophene or indacenodithiophene donor units alternated with either carbo[6]helicene or dimethoxycarbo[6]helicene as chiral inducers were synthesized by using Stille cross-coupling conditions. The obtained enantioenriched oligomeric species exhibited chiroptical properties that differed significantly from those of the monomeric units. With the extensive support from theoretical calculations, the influence of chemical and rotameric structure was analyzed, and the transfer of the chiral response from the helicenic part to the achiral part of the oligomers was demonstrated both in absorption and in emission. Accordingly, the resulting compounds proved to be efficient chiral absorbers and emitters, with absorption dissymmetry factors gabs reaching 10–2 and emission dissymmetry factors glum up to 4.0 × 10–3.