Scientists use microwaves to understand how water affects molecular switches
The findings of this research have been published in two scientific papers in the journal ‘Angewandte Chemie International Edition’.
A team of researchers from the Department of Physics of the Faculty of Sciences and Technology of the University of Coimbra (FCTUC) is using microwaves to explore how water interferes with tiny molecules known as molecular switches.
The findings of this research are presented in two papers published in the prestigious journal Angewandte Chemie International Edition, within the scope of the project MiCRoARTiS – Microwave Fingerprinting Artificial Molecular Motors in Virtual Isolation, coordinated by Sérgio Domingos, Professor at the Department of Physics, and funded by the European Research Council (ERC).
As Sérgio Domingos explains, “Molecular switches are molecules whose functionalities can be tailored when synthesised in the laboratory. They can be programmed to act like ‘nano-switches’: they change shape when exposed to light, which allows them to switch ‘on’ or ‘off’ its availability to interact with other systems.”
Such molecules are key building blocks for future molecular machines, with potential applications in medicine, biology, and nanotechnology.
As part of the MiCRoARTiS project, which is coordinated by Professor Sérgio Domingos and funded by the European Research Council (ERC), the team studied two molecular switches that were almost identical, differing only in minor structural details. They used a microwave spectrometer, which allowed them to observe the three-dimensional structure of the molecules in great detail and capture their rotational spectrum.
According to the researchers, this rotational spectrum acts like a “quantum barcode”: each molecule has a unique pattern, allowing the team to “tell apart not only different types of molecules, but also the different shapes that the same molecule can take — as with molecular switches, which can exist in either an open or closed form,” they explain.
© DR
The researchers further explain that after understanding how these molecular switches behave on their own, without interference from neighbouring molecules, they gradually added water molecules, one by one, to see what changes occur when the switch is surrounded by water. They observed that even a few water molecules are enough to shift the balance between the open and closed forms.
According to Nuno Campos, a PhD student and first author of one of the papers, this finding helps explain how the local environment — even on a very small scale — can affect molecular behaviour.
The second paper examines another molecular switch, seemingly simpler, but which proved challenging for high-level computational chemistry models. This work highlights the importance of experimental measurements in validating theoretical predictions. It was recognised as a Hot Paper by the journal and selected to illustrate one of its covers.