Photoswitching of an intramolecular chiral stack in a helical tetrathiazole.

On-off photoswitching of circularly polarized luminescence was achieved using a pyrene-bearing helical tetrathiazole, in which two pyrene fluorophores stack in a chiral fashion (folded state). The pyrene-excimer based CPL was reversibly controlled by a geometrical change of the tetrathiazole upon photoisomerization.