Macrocyclic Oligothiophene with Stereogenic [2.2]Paracyclophane Scaffolds: Chiroptical Properties from π‐Transannular Interactions

The enantiomers of a new cyclic oligothiophene, bridged by two pseudo‐ortho[2.2]paracyclophanes, were synthesized as a new class of the chiral π‐conjugated system. Single‐crystal X‐ray diffraction analysis revealed a twisted structure for these oligothiophenes induced by a torsion of the cyclophane moieties. The embedding oligothiophenes into the inherent planar chirality provided a significant enhancement in circular dichroism (CD) spectra thanks to the large magnetic/electric transition dipole moments. In the dicationic state, an intramolecular π dimer was formed due to the strong interactions of the oligothiophenes. We further recorded unprecedented wide ranges of CD spectra in 250–1800 nm region. The transitions are reasonably described by the exciton coupling of the oligothiophenes. Cyclophanes: The enantiomers of a new cyclic oligothiophene derived from planar chiral [2.2]paracyclophanes were synthesized. Intense circular dichroism (CD) was observed due to the large magnetic/electric transition dipole moments. In the dicationic state, an intramolecular π dimer, which exhibited a pronounced CD response up to 1900 nm, was formed (see figure).