Chiroptical Properties of Chiral Macrocycles Composed of Axially Chiral Binaphthyl and Bithiophene

Stereogenic macrocycles composed of axially chiral binaphthyls and bithiophenes were synthesized. The bis(1,5-cyclooctadiene)nickel(0)-catalyzed coupling of an enantiomeric precursor yielded a cyclic dimer and trimer with doubly-twisted and triply-twisted triangular geometries, respectively. The orientation of the bithiophenes, s-cis, and s-trans in the cyclic compounds significantly altered their macrocyclic structure. Mixing of conformers in the cyclic dimer results in complex chiroptical properties, leading to bisignate-type spectra, which are rarely observed in circularly polarized luminescence.