Interconversion between Möbius chiroptical states sustained by hexaphyrin dynamic coordination.

Harnessing the chiroptical properties of molecular Möbius rings is motivated by fundamental aspects while challenged by synthetic difficulties. Focusing on Möbius aromatic Zn(ii) hexaphyrin complexes, interconversion between two chiral states was achieved through binding and release of an amino ligand (forward/backward stimuli), leading to different chiroptical switching phenomena (amplification, on-off, inversion). The amine either supplies the chirality or behaves as an achiral effector regulating the Zn(ii)-binding of a second (chiral) carboxylato ligand. These results highlight the Möbius [28]hexaphyrin scaffold as an attractive chiral switchable unit.