Scientists have confirmed a decades-old theory about the non-uniform electron density distribution in aromatic molecules, thereby expanding the possibilities for designing new nanomaterials. This study builds on their previous research and uses advanced scanning electron microscopy for subatomic analysis.
Researchers have experimentally verified the old theory that the electron density is not evenly distributed in aromatic molecules.
Researchers from the Prague IOCB, the Physics Institute of the Czech Academy of Sciences and the Palatski Olomouc University have once again achieved great progress in unraveling the mysteries of the molecular and atomic worlds. They experimentally verified the old theory that the electron density is not evenly distributed in aromatic molecules.
This phenomenon greatly affects the physical and chemical properties of molecules and their interactions. This research expands the possibilities for designing new nanomaterials and is the subject of a recently published paper Nature Communications.
The same author team in a previous pilot study published in Science Describe the disordered distribution of electrons in Corn, which are called σ holes. Now researchers have confirmed the existence of π holes. In aromatic hydrocarbons, electrons are found in the cloud above and below the plane of the carbon atoms. If we replace the surrounding hydrogen atoms with more electronegative atoms or groups of atoms that attract electrons, the initially negatively charged cloud turns into positively charged electron holes.
Professor Pavel Hobza, Distinguished Chair and Chair of the Non-Covalent Interactions Group at IOCB Prague. Credit: Thomas Bellon/IOCB Prague
Scientists have used sophisticated methods of scanning electron microscopy and improved its capabilities even further. This method works at subatomic resolution, so it can describe not only the atoms in a molecule, but also the structure of the atomic electron shells. As one of the researchers, Bruno de la Torre of the Czech Institute of Technology and Advanced Research (CATRIN) at Palatske Olomouc University, points out, the success of the experiment described here is due primarily to the excellent facilities at the institution it originated from. and a Ph.D. student.
“Thanks to our previous experience with Kelvin probe force microscopy (KPFM) technology, we were able to improve our measurements and obtain very complete data sets that helped us deepen our understanding beyond just how charges are distributed in molecules. using this technique.
Experimental measurements confirm theoretical predictions about the existence of π holes. From left to right: chemical structures of investigated molecules, calculated electrostatic potential maps of molecules, experimental Kelvin probe force micrographs (KPFM), and simulated images of KPFM. Credit: IOCB Prague
Modern style microscopy has long been the domain of researchers at the Institute of Physics. Not only in the case of molecular structures, they use unprecedented spatial resolution to the maximum. Some time ago they confirmed the existence of a non-uniform distribution of electron density around halogen atoms, which are called σ holes. This achievement was published in 2021 by Science. Previous and current research is contributed greatly by one of the most cited Czech scientists today, Professor Pavel Hobza of the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague).
“Confirmation of the existence of π holes, as well as those of σ holes that precede them, fully demonstrates the theoretical predictive qualities of quantum chemistry, which has been responsible for both phenomena for decades. reliable even in the absence of available experiments,” says Pavel Hobza. .
The results of Czech scientists’ research at the subatomic and submolecular level can be compared to the discovery of cosmic black holes. They also theorized for decades before its existence was confirmed through experiments.
Better knowledge of the charge distribution of electrons will help the scientific community understand many chemical processes and especially biological processes. On a practical level, this will translate into the ability to build new supermolecules and then develop advanced nanomaterials with even better properties.
Reference: “Visualization of π holes in molecules with Kelvin probe force microscopy” by B. Mallada, M. Ondráček, M. Lamanec, A. Gallardo, A. Jiménez-Martín, B. de la Torre, P. Hobza and B. . Jelinek, 16 August 2023, Nature Communications.
two: 10.1038/s41467-023-40593-3
2023-09-06 22:24:15
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