Time‐Programable Chiroptical Response From a Möbius Totemic Architecture

Information handling at the molecular level can be achieved by appropriate control of the chiroptical response of a chromophore. In this context, a dynamic Möbius aromatic π‐system, embedded in a 3‐type chirality totem edifice, has been investigated, targeting a time‐dependant protonation control of its stereoselective winding. The mono‐protonation of the so‐called hexaphyrin‐cyclodextrin hybrid (HCD) was therefore carried out with either stable (e.g. methanesulfonic acid) or unstable (trichloroacetic acid [TCA]) acids producing a drastic increase of the chiroptical activity resulting from a favored M ‐twist ( d.e. ∼75%). Using TCA, the mono‐protonation becomes a transient state, turning the static chiroptical response into a dynamic one whose time domain varies from minutes to hours, depending on the solvent composition or the amount of acid. More importantly, the way‐back process (back deprotonation), that relies on the decomposition of the Cl 3 CCO 2 – counter‐anion, was significantly accelerated by exchange with Cl – . As a result, addition and trapping of Cl – anion allows to switch between a dissipative and a static chiroptical response of the TCA induced mono‐protonated species. This remarkable temporal control over a chiroptical signal paves the way for the design of Möbius‐type devices for molecular encoding and signaling.