- and -Symmetric Configurationally Stable Pyrene-Fused [5]Helicenes Connected via Hexagonal and Heptagonal Rings.

In this paper, we describe the stereospecific synthesis and functional properties of - and -symmetric pyrene-fused [5]helicene molecules and connected via hexagonal and heptagonal rings, respectively. Both molecules showed high configurational stability and distinct functional properties, which were attributed to the fusing mode of [5]helicene with the pyrene and molecular symmetry. The estimated Gibbs activation energy for enantiomerization of is one of the highest reported values for any π-conjugated molecules incorporating [5]helicene moiety.