Geneva, July, 9th 2025 - Dr Pierrick Berruyer.

Professor Rickhaus' group, in collaboration with scientists from the Universities of Zurich and Geneva, publishes its first article in the Journal of American Chemical Society since the group moved to the Section of Chemistry and Biochemistry at the University of Geneva.

Having joined the Department of organic chemistry just two years ago, assistant professor Michel Rickhaus and his team design superstructures from small molecules, which they fold and assemble like puzzle pieces. These structures form materials capable, for example, of transporting electricity or light. The group explores both the creation of these molecular architectures and their potential as innovative materials for tomorrow.

In this publication, published on May 18, 2025, in the Journal of American Chemical Society, Prof. Rickhaus and his team focus on molecules called carpyridines, shaped like microscopic saddle. Just like the famous potato chips of the same shape, these molecules have the ability to stack on top of each other, a bit like tidy plates.

The researchers were interested in how these molecules stack up depending on the amount of water present. They have shown that, in the absence of water, the molecules stick together. In this "dry" stacking, the molecules arrange themselves only by π-π bonds, and the direction of the molecules alternates regularly. In the presence of water, the stacking changes: water molecules are inserted between the carpyridine molecules and bond to them by hydrogen bonding. This gives rise to a new, perfectly straight, more regular architecture, with a water molecule between each carpyridine. It is thus possible to regulate stacking on a nanometric scale, as if the carpyridines were acting as tiny sponges, "swelling" in the presence of water to better stack.

In this new architecture, water enables the creation of a more porous structure, with the existence of tiny regular channels. This discovery opens up prospects for applications such as gas adsorption.

Researchers have shown that it is possible to switch from one structure to another by adjusting the quantity of water. Here, water becomes a real player in molecular construction.