UC scientist studies structural evolution of chiral clusters of key interstellar molecules

Sérgio Domingos, professor and researcher at the Department of Physics, Faculty of Science and Technology, University of Coimbra (FCTUC), is studying the evolution of ionisation energy and molecular aggregation motifs with the stepwise growth of chiral clusters.

The study, published in Nature Communications, focuses on forming [4] helicene clusters - when at least four aromatic rings form a helical chiral structure).

Helicenes are the smallest of the polycyclic aromatic hydrocarbons (PAHs), which are highly relevant molecules for the study of chemical processes in the interstellar medium (ISM), as they are so abundant in space.

Domingos explains that this type of molecule typically exists in two forms (enantiomers) that are mirror images of each other, just like our hands. "Just as our left hand fits perfectly into a left glove, at the molecular level the precise fit between two or more chiral molecules can create a preference for certain types of these molecules, which may influence their relative abundance in small particles. This may have influenced how organic matter has evolved since life began on Earth," he explains.

This work, carried out at the SOLEIL facilities in Paris, brought together scientists from several countries (Germany, Spain, France and Portugal), who were able to obtain theoretical structural models that confirmed changes in the ionisation energy and showed a clear trend towards the formation of clusters of molecules of the same chiral nature. “These results are highly significant for the way we view cluster formation in the interstellar medium, on the scale of small grains”, the UC researcher concludes.

The paper “Evolution of the ionisation energy with the stepwise growth of chiral clusters of [4]helicene” is available here.