An international research team led by the University of Vienna has developed a groundbreaking method that can be used to directly measure partial charges in molecules for the first time. The findings, published in Nature, offer new insights into the electrostatic properties of molecules and could revolutionize drug development and materials science.

Partial charges, small imbalances in the electron distribution within a molecule, are crucial for chemical and biological processes. They determine how molecules interact with each other and influence the absorption, distribution and effect of drugs in medicine, for example. Until now, partial charges could only be estimated theoretically, which led to different results depending on the calculation method. The new method now enables an experimental determination of these charges.

The team, led by Tim Grüne, head of the Core Facility for Crystal Structure Analysis, and Christian Schröder from the Institute of Computational Biological Chemistry, used electron diffraction to measure the partial charges. In this process, an electron beam is directed at a tiny crystal that reacts sensitively to the electrostatic potential. A camera specially developed at the Paul Scherrer Institute in Switzerland recorded the minimal deflections of the beam. In combination with a new analysis method, so-called ionic scattering factor modeling (iSFAC), the researchers were able to precisely quantify the charges of individual atoms.

The method has been tested on various substances, including the industrial catalyst ZSM-5, the amino acids tyrosine and histidine, tartaric acid and the antibiotic ciprofloxacin. In the case of ciprofloxacin, the analysis showed that the chloride ion carries only about 40 percent of the negative charge, which illustrates the strong dependence of the charge distribution on the molecular environment.

The new technology offers far-reaching application possibilities. It not only enables the validation and further development of theoretical models, but also opens up perspectives for the development of more precise drugs with fewer side effects and for the production of tailor-made materials. The advances in electron crystallography that have been advanced at the University of Vienna mark an important step towards a deeper understanding of molecular properties and their targeted use in science and industry.

Original Paper:

Experimental determination of partial charges with electron diffraction | Nature

Editor: X-Press Journalistenbüro GbR

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