<i>C</i>₂- and <i>C</i>₁-Symmetric Configurationally Stable Pyrene-Fused [5]Helicenes Connected via Hexagonal and Heptagonal Rings

Abstract

In this paper, we describe the stereospecific synthesis and functional properties of <i>C</i>₂- and <i>C</i>₁-symmetric pyrene-fused [5]helicene molecules <b>1</b> and <b>2</b> 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 <b>2</b> is one of the highest reported values for any π-conjugated molecules incorporating [5]helicene moiety.