Scientists from ETH Zurich and the University of Geneva have developed a new technique that allows them to observe chemical reactions occurring in liquids with very high temporal resolution. This innovation makes it possible to track how a molecule changes within just femtoseconds, i.e. within 1/1000th of his second.
This breakthrough builds on previous research by the same team led by Hans-Jacob Werner, professor of physical chemistry at ETH Zurich. This study yielded similar results for reactions occurring in gaseous environments.
To extend X-ray spectroscopy observations to liquids, the researchers needed to design a device that could generate liquid jets less than 1 micrometer in diameter in vacuum. This was essential because if the jet was wider, some of the X-rays used in the measurements would be absorbed.
Molecular pioneer in biochemistry
Using this new method, researchers were able to gain insight into the processes that led to the emergence of life on Earth. Many scientists believe that urea played an important role here. It is one of the simplest molecules containing both carbon and nitrogen.
Moreover, it is very likely that urea was present even when the Earth was very young, as suggested by a famous experiment conducted in the 1950s. American scientist Stanley Miller prepared a mixture of these gases that are believed to make up the primordial planets. When exposed to thunderstorm conditions in air. This produced a series of molecules, one of which was urea.
According to current theory, urea may have been concentrated in warm pools of water (commonly called primordial soups) on Earth, where life did not exist at the time. As the water in this soup evaporated, the concentration of urea increased. Upon exposure to ionizing radiation such as cosmic rays, this concentrated urea could have produced malonic acid. acid over multiple synthetic steps. This could have created constructs such as: RNA and DNA.
Why did this reaction occur?
Researchers from ETH Zurich and the University of Geneva used a new method to investigate the first step in this long series of chemical reactions, and how concentrated urea solutions behave when exposed to ionizing radiation. I checked whether
It is important to know that the urea molecules in a concentrated urea solution group themselves as pairs, or dimers. Ionizing radiation produces hydrogen, as researchers can now prove. atom Within each of these dimers it moves from one urea molecule to another. This changes one urea molecule into a protonated urea molecule and the other into a urea radical. The latter is highly chemically reactive, in fact so reactive that it is very likely to react with other molecules to form malonic acid as well.
The researchers were also able to show that this transfer of hydrogen atoms occurs very quickly, taking only about 150 femtoseconds, or 1.5 quintillionths of a second. “It’s so fast that this reaction theoretically pre-empts all other reactions that could occur,” Werner says. “This explains why concentrated urea solutions produce urea radicals rather than undergoing other reactions that produce other molecules.”
Reactions in liquids are highly relevant
In the future, Werner and his colleagues would like to investigate the next step leading to the production of malonic acid. They hope this will help them understand the origin of life on Earth.
As for their new method, it can also be used to investigate the exact order of chemical reactions in liquids in general. “Many important chemical reactions take place in liquids, including not only all biochemical processes in the human body, but also a great many chemical syntheses relevant to industry,” Werner says. “This is why it is so important to extend the scope of his X-ray spectroscopy at high temporal resolution to include reactions in liquids.”
Reference: “Femtosecond proton transport in urea solutions investigated by X-ray spectroscopy” Zhong ying, Yi-Ping Chang, Tadas Balčilungas, Yashoj Shakya, Aleksa Djorović, Geoffrey Gaulier, Giuseppe Fazio, Robin Santra, Ludger Inhester, Jean -By Pierre Wolf and Hans Jakob Werner, June 28, 2023, Nature.
DOI: 10.1038/s41586-023-06182-6
Researchers from ETH Zurich and the University of Geneva carried out the study with support from colleagues at the Deutsche Elektronen Synchrotron. DESY A Hamburg doctor performed the calculations necessary to interpret the measurement data.