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Researchers produce videos on chemical synthesis at atomic resolution for the first time

  Chemistry in motion
Electron micrographs of the specimen at different magnifications. Credit: (c) 2019 Nakamura et al.

For the first time, researchers have been able to reveal previously unavailable details of certain chemical processes. They have shown that there are significant discrete phases in these processes that build on existing knowledge of chemical synthesis. These details may help to develop methods for the synthesis of chemicals with greater control and precision than ever before. Methods like these could be useful in materials science and drug development.

"Since 2007, physicists have realized a dream over 200 years old ̵

1; the ability to see a single atom," said Project Professor Eiichi Nakamura. "But it did not end there – our research group has gone beyond this dream to create videos of molecules to see chemical reactions in unprecedented detail." chemical processes responsible for material synthesis. However, chemical synthesis is a complicated field of research.

"Conventional analytical methods such as spectroscopy and crystallography provide useful information about the results of processes, but only give indications of what happens during these processes," said Koji Harano, Project Associate Professor in the Nakamura Group. "For example, we are interested in organometallic framework (MOF) crystals, and most studies are concerned with their growth, but overlook the early stage of nucleation because it is difficult to observe."

  Chemistry in Motion
A video showing for the first time the cubic molecule crucial for MOF crystals. Credit: (c) 2019 Nakamura et al.

The transition states of complex chemical reactions are difficult to study, as there are several intermediate processes between the beginning and the end of most reactions. In principle, the individual phases were visible, but in reality it was impossible to isolate the products in each phase and see how they changed over time. Nakamura, Harano, and his team spent over 10 years on this issue, developing a method called molecular electron microscopy.

"The problem was two parts," said Harano. "On a large scale, a technical challenge was to combine a uniquely high-resolution electron microscope with a fast and sensitive image sensor for continuous video imaging on a small scale we had to find a way to capture the molecules of interest and capture them so that the camera would capture the Encouraging action. "

To isolate and secure certain molecules, the team used a specially modified carbon nanotube. This would catch a passing molecule and hold it in place, but it would be crucial that it does not interfere with the reactions of that molecule. In this way, each reaction step would take place at the tip of the nanotube, which in turn was positioned at the focal point of the electron microscope. The resulting data can be recorded in real-time video of the reactions.

  Chemistry in Motion
Project collaborator Professor Harano at the control of the unique electron microscope of the research group. Credit: (c) 2019 Harano et al.

"What initially surprised us was that our plan actually worked, it was a complex challenge, but we first visualized these molecular videos in 2013," Harano said. "From then until now, we've been working to transform the concept into a useful tool, and our first success was to visualize and describe a cube-shaped molecule that is a crucial intermediate in MOF synthesis." It took a year to we were convinced critics found that what we found is real. "

This is just the first step in gaining control over chemical synthesis precisely and in a controlled manner-a notion the researchers call" rational Synthesis "denote. It is important to keep track of the details of the reactions in the process so that they can be effectively regressed. The dream 200 years ago was to see an atom; The dream is now to control molecules to create things like synthetic minerals for construction, or even new life-saving medicines.

Researchers dramatically simplify and rationalize organic chemical synthesis

Further information:
Junfei Xing, Luca Schweighauser, Satoshi Okada, Koji Harano and Eiichi Nakamura. Atomic structures and dynamics of prenucleation clusters in MOF-2 and MOF-5 syntheses. Nature Communications . DOI: 10.1038 / s41467-019-11564-4

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University of Tokyo

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Researchers produce first-time chemical synthesis videos at atomic resolution (2019, 23 August)
retrieved on 23rd August 2019
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