Oxa-TriQuinoline: A New Entry to Aza-Oxa-Crown Architectures

A new 15-membered-macrocyclic molecular entity, oxa-TriQuinoline (o-TQ), was designed and synthesized. In o-TQ, three oxygen atoms were joined onto three quinoline units at the 2- and 8-positions in a head-to-tail fashion by three-fold S_N Ar reactions, giving rise to the characteristic N₃ O₃ aza-oxa-crown architecture. o-TQ can serve as a new tridentate nitrogen ligand to capture a Cu^I cation and adopt a bowl shape, before supramolecular complexation with corannulene and [12]cycloparaphenylene (CPP) occurs through π-π and CH-π interactions. In the presence of the Cu^I cation, the non-emissive o-TQ becomes a highly emissive material in the solid state, whereby the emission wavelengths depend on the ancillary ligand on the Cu^I cation. The o-TQ/Cu^I complex is able to promote carbene catalysis to provide a range of enamines with a gem-difluorinated terminus.