Controlled blossoming of a "molecular flower"

By succeeding in changing the shape of a synthetic molecule, researchers have paved the way for the elaboration of complex macromolecular systems.

Chemists from the LCC1Laboratoire de Chimie de Coordination (CNRS/Université Toulouse III – Paul Sabatier/INP Toulouse), the LISE2Laboratoire Interfaces et Systèmes Electrochimiques (CNRS/Sorbonne Université) and the LIMA3Laboratoire d’Innovation Moléculaire et Applications (CNRS/Université de Strasbourg/Université de Haute-Alsace) have succeeded in controlling the folding and unfolding of a macromolecule that had been previously synthesized, using different types of stimulation. Sixty times bigger than an aspirin molecule, this polymer is composed of a central part surrounded by ten identical units that include a zinc atom. By cooling the medium to minus 70 °C, each zinc atom binds to a group situated between the centre and the periphery of the molecule, forcing the latter to fold. In contrast, when the medium is heated to 100°C, these chemical bonds break, causing the molecule to unfold.

The researchers have even succeeded in obtaining this change in form in two other ways. By an oxidation- or in contrast a reduction reaction, they could make or break the same chemical bonds. Furthermore, upon placing the macromolecule in the presence of a specific ligand, the latter was found to prevent the chemical bonds from forming, triggering the blossoming of this “molecular flower”.

These results could help improve researchers’ understanding of how the three-dimensional structures of biological molecules influence their activity. They also pave the way for the possible development of complex macromolecular systems with properties or functions that could be controlled merely by changing their shape.

Chemistry—A European Journal, 2017