FCTUC / Cortesia
Scientists use microwaves to discover how water interferes with the functioning of molecular switches.
A team of researchers from the Department of Physics (DF) of the Faculty of Science and Technology of the University of Coimbra (FCTUC) uses microwaves to discover how water interferes at a microscopic level with the functioning of molecular switches.
Molecular switches are molecules with functionalities that can be “custom-configured” when synthesized in the laboratory.
Researcher Sérgio Domingos adds that these molecules can be programmed to function as a “nano-switch” which changes its three-dimensional structure when it receives pulses of light with specific wavelengths that, consequently, can “turn on” and “turn off” its availability to interact with other systems.
Molecules capable of performing these functions reproducibly are fundamental building blocks in the conceptualization of synthetic molecular machines for a variety of applications in biology, medicine and molecular nanotechnology.
“The team studied the relationship between the three-dimensional structure and the energy balance of two molecular switches with the same chassis, but with different mobile units”, describes Sérgio, researcher at the Physics Center of the University of Coimbra (CFisUC).
“In our research group, we use a high-resolution spectroscopy technique, which allows us to observe the three-dimensional structure of these molecules in their gas phase. To do this, we use our microwave spectrometer to irradiate and, subsequently, collect the emission from the molecules in order to capture their rotational spectrum”, add the researchers.
This rotational spectrum is basically a “quantum barcode”indicates the research team.
“Just as a barcode identifies each product in the supermarket, this rotational spectrum is a unique line pattern for each molecule. This allows us to distinguish not only different molecular species (different chemical formulas), but also the different structures that the same chemical species can adopt, as is the case with molecular switches that have two possible structures: open or closed”, they clarify.
The first step is to understand how these molecular switches behave alone and without interference from other neighboring molecules.
Then, observe how this system behaves in solution, adding one water molecule at a time to the molecular switch.
The first showed that, when adding water to the system, the balance between the open/closed form is compromisedinverting the switch position preference.
“This observation is highly relevant, because it informs us how the properties of this system can change significantly when surrounded by just a few water molecules”, says author Nuno Campos.
The second analyzes another molecular switch, predictably simpler, but which turned out to be a challenge for many of the high-level theoretical computational chemistry models.
This study culminates in a note to the scientific community for the importance of not blindly trusting theoretical predictionshighlighting the fundamental role of experimental measurements to validate structural and dynamic information of complex molecular systems.
