Construction of helical structures with multiple fused anthracenes: structures and properties of long expanded helicenes

Kei Fujise, Eiji Tsurumaki, Kan Wakamatsu, Shinji Toyota

Polycyclic aromatic compounds consisting of four or five fused anthracene units were synthesized by PtCl2-catalyzed cycloisom erization as novel long expanded helicenes. These compounds have helical structures with signif icant stacking of the terminal anthracene moieties at 0.33 nm interlayer distance. In the UV-vis and fluorescence spectra, the absorption and emission bands were red-shifted as the number of fused anthracene units was increased. The characteristic broad and long-lived emission bands of the long analogs are explained by the excimer-like stabilization of the excited state. These photophys. data as well as their cyclic voltammetric data are discussed on the basis of the π- conjugation and interlayer π···π interactions in the mol. structures and the M Os. The barrier and mechanism of helical inversion are also reported.

Chem. Eur. J.

27

14

4548

4552

10.1002/chem.202004720