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After 17 years of research, scientist solves one of the holy grails of physical chemistry

After 17 years of research, scientist solves one of the holy grails of physical chemistry
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Scientist resolves one of the holy grails of physical chemistry after 17 years of research Absolute cross sections scaled per oxygen atom. Absolute cross sections per oxygen atom for a larger frequency range, derived from the XAS measurements on hydrated proton complexes and on water in acetonitrile. Recognition: International edition of Angewandte Chemie (2022). DOI: 10.1002/anie.202211066

Prof. Ehud Pines is an iconoclast. What else can you call a scientist who spent 17 years doggedly searching for the solution to a 200-plus-year-old chemical problem that he believed never received a satisfactory answer using methods no other scientist believed had they could lead to the truth? Now he is confirmed applied Chemistry published a cover article detailing how his experiment was replicated by another research group while being X-rayed to reveal the solution Prof. Pines has been arguing for all along.

The question is: how does a proton move through water? In 1806 Theodor Grotthuss presented his theory, which became known as the Grotthuss mechanism. Over the years many others tried an updated solution, realizing that Grotthuss was strictly wrong, but it remained the standard textbook answer. Until now.

Prof. Ehud Pines, based on his experimental studies at Ben-Gurion University of the Negev together with his Ph.D. Student Eve Kozari and theoretical studies by Prof. Benjamin Fingerhut on the structure of the protonated water clusters by Prof. Pines, that the proton moves through water in trains of three water molecules.

The proton trains “build the tracks” beneath them for their locomotion, and then disassemble and rebuild the tracks in front of them to move on. It is an endless loop of disappearing and reappearing tracks. Similar ideas have been put forward by a number of scientists in the past, however, according to Prof. Pines, they have not been assigned to the correct molecular structure of the hydrated proton, which leads to the promotion of the Grotthuss mechanism through its unique trimeric structural properties.

“The debates about the Grotthuss mechanism and the nature of proton solvation in water have become heated,” says Prof. Pines, “as this is one of the most fundamental challenges in chemistry. Understanding this mechanism is pure science, pushing the frontiers of our knowledge and transforming one of our fundamental understandings of one of nature’s most important mass and charge transport mechanisms.”

While additional theoretical studies in recent years have corroborated Prof. Pines’ findings about the hydrated proton captured by a chain of three water molecules, most of the global scientific community working in the field has remained reluctant to support Prof. Pines ‘ Accepting emerging model for proton solvation and motion in water. Therefore, Prof. Pines turned to long-time employees of the Max Born Institute in Germany.

They assembled an international research team led by Dr. Erik Nibbering, and repeated the experiment, this time examining the chemical system. The X-ray experiment – which required specially designed equipment costing millions of dollars and was funded by the European Research Council – confirmed Prof Pines’ findings.

The X-ray absorption (XAS) experiment measured the effect of the proton charge on the structure of the inner electrons of the individual oxygen atoms of water. As predicted by Prof. Pines, three water molecules were found to be most affected by the presence of the proton, each to different degrees, and together with the proton form protonated 3-water molecule chains or “trains”.

“Everyone has been thinking about this problem for over 200 years, so that was enough of a challenge for me to decide to tackle it. Seventeen years later I am very satisfied to have most likely found and demonstrated the solution,” says Prof. Pines.

The next edition of the college chemistry textbooks may replace the description of the Grotthuss mechanism with the “Pines mechanism,” an idea that tickles Prof. Pines but is only an oddity compared to the revelation that this fundamental mechanism is one of the most common understand and basic processes in nature.


Physicists extract the mass radius of protons from experimental data


More information:
Maria Ekimova et al., From Local Covalent Bonding to Extended Electric Field Interactions in Proton Hydration, International edition of Angewandte Chemie (2022). DOI: 10.1002/anie.202211066

Provided by Ben Gurion University of the Negev

Citation: Scientist solves one of the holy grails of physical chemistry after 17 years of research (2022, September 29), retrieved September 29, 2022 from https://phys.org/news/2022-09-scientist-holy-grails-physical -chemistry.html

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