Article in Chemical Communications (2025)

27 09 2025

Molecular Chains for Ion Transport

When chains are reduced to the nanoscale, they form a fascinating class of mechanically interlocked molecules known as catenanes. The team led by Prof. Michał Chmielewski has constructed a catenane capable of transporting anions across lipid bilayers. Molecules with such functionality are of great interest due to their potential biological activity, especially anticancer and antibacterial.

Transporting anions across cell membranes is a formidable challenge, as charged particles are reluctant to penetrate the lipophilic interior of a lipid bilayer. In living organisms, this task is carried out by specialized proteins that maintain proper ion concentrations on both sides of the membrane.

For many years, researchers have been striving to mimic this function by designing synthetic molecular receptors. These molecules can selectively bind specific ions and facilitate their passage through membranes, often exhibiting intriguing biological activity and therapeutic potential.

The team of researchers from the Laboratory of Supramolecular Chemistry, led by Prof. Michał Chmielewski, has now developed an anion transporter with a unique topology. The compound consists of two identical macrocyclic rings, mechanically interlocked like links of a chain. Each ring contains a cavity with strong affinity for anions and is oriented almost perpendicularly to the other. As a result, at the junction of the two rings a three-dimensional binding site is formed, in which the anion is effectively shielded from the surrounding environment, allowing it to easily pass through lipid barriers. Moreover, the mechanical bond between the macrocycles grants the catenanes with flexibility, which facilitates both anion binding and release.

The researchers hope that in the future catenanes will enable the transport of particularly challenging ions, such as phosphate anions.

This work was supported by the NCN OPUS grant entitled “Selective transport of biologically important anions across lipid bilayers” (OPUS 2018/31/B/ST5/02085).

Publication details:
K. M. Bąk, O. Kisiel, D. Mondal, M. M. Zimnicka, M. J. Chmielewski “Anion transport across lipid bilayers by a hydrogen bonding homo[2]catenane” Chem. Commun., 2025, 61, 13900-13903, DOI: 10.1039/D5CC02888D

Link to the team’s website: https://www.mchmielewski.pl/en/home/