# A Foldaxane‐Based Supramolecular Muscle‐Like Switch

## TL;DR

Scientists created a molecular muscle-like switch using foldaxane structures that can contract and stretch in response to chemical stimuli.

## Contribution

The first supramolecular muscle-like switch based on foldaxane was developed, showing controlled contraction and stretching.

## Key findings

- The foldaxane-based switch can transition between contracted and degenerate-like states using a bulky Fmoc group.
- The assembly is kinetically stable, with disassembly slower than the gliding of helixes along molecular rods.

## Abstract

[cn]daisy chain molecular muscle architectures are self‐assemblies of hermaphrodite monomers, which usually contain a macrocycle unit linked to a molecular thread that contains sites of interactions – i. e. molecular stations – for the macrocycle. In these multiply threaded structures, altering with control the affinity between macrocycles and stations allows for contraction and extension of the molecule, which is reminiscent of the operation of a muscle. Besides, the field that consists of combining helix and template‐containing rods to design foldaxane supramolecular assemblies is still underexplored. By using foldamer units as surrogates for macrocycles, Gan et al. reported the first supramolecular muscle‐like foldamer‐containing switch that can adopt, after chemical stimulus, either a contracted co‐conformational state or a degenerate‐like state for which a slow exchange occurred between the contracted and the stretched state.

Quan Gan and co‐workers report the first supramolecular foldaxane‐based molecular muscle. The molecule is able to adopt a contracted state or a degenerate‐like state through the gliding of helixes between the contracted and stretched states, upon the invertible introduction of a bulky Fmoc group. Noteworthy, the supramolecular assembly is kinetically stable since its disassembly is much slower than gliding of the helix along the molecular rods.