Chiral diversification through the assembly of achiral phenylacetylene macrocycles with a two-fold bridge
We demonstrate so-called “chiral diversification”, which is a design strategy to create multiple chiral molecules through the assembly and double-bridging of achiral components. We used phenylacetylene macrocycles (PAMs) as an achiral element. In a molecule, two achiral rings of PAM are stacked one above the other, or bound to each other mechanically. As an alternative, a single enlarged ring of PAM was also assumed to be a doubled form of PAM. In any case, one or two ring(s) are doubly-bridged by covalent bonds to exert chirality. Through intramolecular two-bond formation, these multiple chiral molecules were obtained as a set of products in one reaction. The dynamic chirality generated in molecules with either two helically-stacked rings of PAM or a single helically-folded ring of PAM was characterized by induced Cotton effects with the aid of an external chiral source. Thus, a chiral structure based on PAM could be demonstrated as the first success. Alternatively, enantiomeric separation was achieved for molecules with two interlocked rings of PAM to show remarkable chiroptical properties.
- This article is part of the themed collection: 2019 Chemical Science HOT Article Collection