Many molecules exist in two different variants that are mirror images of each other, like our right and left hand. They are called chiral molecules. They consist of exactly the same atoms, but can behave completely differently in medical applications, for example.
It is extremely difficult to understand how one chirality or the other arises during the formation of such molecules. Both variants are formed from the same building blocks at the same temperatures and under the same external conditions. However, Noelia Barrabés from the Institute of Materials Chemistry at TU Wien has now found a new way to better understand chirality in chemical reactions - namely with atomically precise metal nanoclusters particles. She has now been awarded an ERC Consolidator Grant by the European Research Council (ERC), one of the most prestigious and highly endowed grants in the European research landscape.
Healing or harmful?
The problem of mirror-inverted molecules became sadly famous as a result of the thalidomide affair in the 1950s and 1960s: Back then, thousands of children were born with deformities because the molecule occurs in two different forms: a left-handed and a right-handed one. They have completely different effects on the human body: one variant is a well-tolerated sleeping pill, while the other can lead to malformations if taken during pregnancy.
Today, there are technical possibilities to specifically produce only one version of a molecule in chemical reactions and not its mirror image. However, these techniques are mainly successful implemented in solutions using chiral catalysts, which then have to be separated from the desired product.
In recent years, Noelia Barrabés has taken a different approach: she is working with catalysts that are in solid form and can be fixed to a surface. This would allow much simpler and more efficient industrial use. "If we manage to control the chirality of molecules in this way and understand the process precisely, it would be a major breakthrough in materials research," says Noelia Barrabés. "And the results so far look very promising."
First, small gold clusters are produced, which then serve as catalysts. "Using metal nanoparticles as catalysts is nothing unusual," explains Noelia Barrabés. "But normally you have to deal with a distribution of particle sizes and different surface configurations. In our case, however, the gold clusters are very precisely defined, they all consist of exactly the same number of atoms, therefore it is possible to correlate their chiral properties to their structure."
These gold clusters are then fixed to a surface and provided with additional molecules, the so-called ligands. "We have succeeded in understanding the behavior of these gold nanoclusters at the atomic level," says Noelia Barrabés. "We can therefore produce a surface with nanoclusters that have very specific chiral properties and can therefore also specifically influence chemical reactions on this surface." Barrabés and her team will now investigate exactly what happens in this process - using, among other things, vibrational circular dichroism spectroscopy with the objective to extend the measurements to surfaces, which can be acquired with the funding of the ERC grant. This will allow the chirality properties of various molecules to be observed directly during the chemical reaction.
Noelia Barrabés studied Chemical Engineering in Spain, at the University of Rovira i Virgili in Tarragona. She also completed her dissertation there in 2009. As a doctoral student, she completed several research stays abroad (TU Vienna and Queens University of Belfast). She then went to Montpellier (France) as a postdoc before coming to TU Wien in 2010 with an IEF Marie Curie Fellowship. From 2012, she spent several years at the University of Geneva, funded by an SNSF Marie Heim-Vögtlin fellowship, before returning to TU Wien in 2015, where she completed her habilitation in 2023 in Physical Chemistry. She has already won several prizes and awards, including an Elise Richter Fellowship from the FWF. The ERC Consolidator Grant, endowed with around two million euros, will now allow her to further expand her research work.
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Text: Florian Aigner