Orchestrating Communications in a Three-Type Chirality Totem: Remote Control of the Chiroptical Response of a Möbius Aromatic System.

Among the various types of chirality (central, axial, helical, planar, etc.), that inherent to Möbius topology remains almost unexplored, partly due to the difficulty to access Möbius compounds. Over the past decade, [28]hexaphyrins have been revealed to be among the best candidates to build on Möbius aromaticity. Whereas their flexibility needs to be controlled to get / twist enantioselectivity, it could be of great interest to sustain dynamic chirality transfer. In this context, we report herein the first example of a Möbius aromatic ring capped by a cavity, consisting of a Möbius [28]hexaphyrin doubly linked to an α-cyclodextrin. This unique design affords a "totem" of three different chirality elements arising from the cyclodextrin (fix central chirality), the bridging pattern (dynamic planar chirality), and the hexaphyrin (dynamic topological chirality). Chirality transfers (as shown in the TOC graphic) are characterized by a stereospecific planar-to-topological communication (diastereomeric excess >95%; the highest asymmetric selectivity reported to date for a Möbius ring) combined to a stereoselective central-to-planar communication (up to 60% diastereomeric excess). Interestingly, the stereoselectivity is remotely controlled by coordination of an achiral effector to the hexaphyrin, increasing up to 5 times the chiroptical response of the Möbius aromatic π-system. These results highlight the advantageous use of dynamic chirality transfers to further incorporate Möbius chirality and aromaticity into all kinds of stimuli-responsive devices.