A model for the rapid synthesis of nanographs



June 28, 2021

(Nanowerk News) A group of researchers from Nagoya University, Japan, have developed a new method to quickly and efficiently synthesize nanographs, a type of nanocarbon with great potential as a next-generation material (Nature Communication, “Synthesis oriented towards the diversity of nanographs allowed by the annulative desaromative extension”).

Nanographs are the partial structures of graphene, which is a sheet of carbon atoms about 3 nanometers thick with particular potential for use in semiconductor development, having electron mobility several hundred times better. than current generation materials. Graphene was first isolated in 2004, a discovery that received the Nobel Prize in Physics in 2010, making it a brand new material that is currently the subject of much research.

APEX reactions are performed on the K, M and bay regions of the polycyclic aromatic hydrocarbon, synthesizing multiple nanographenes. These reactions can then be repeated, further increasing the number of potential nanographene structures that can be synthesized. (Image: Issey Takahashi) (click image for larger view)

With magnetic and electrical characteristics beyond those of graphene, nanographs are also of interest to scientists in the field of nanocarbon research. The biggest, albeit exciting, obstacle facing researchers is the sheer number of potential nanographs. The number of potentially possible nanographene structures increases with the number of benzene rings (6 carbon atoms in a hexagonal formation) to make them.

For example, even a relatively small nanographene with 10 benzene rings can have as many as 16,000 variants. Since each nanographene has different physical characteristics, the key to applied nanographene research is to identify the relationship between the structure and characteristics of as many nanographs as possible.

So, the task of scientists is to create a library of nanographs, containing data on the properties of as many nanographs as possible. However, the current method of synthesizing nanographene, known as the coupling reaction, is a multistep process that produces a single nanographene.

Thus, to create a library of 100 nanographenes, it would be necessary to perform 100 separate coupling reactions. Even that would be a major undertaking, making it virtually impossible to build a truly complete nanographene library.

To solve this problem, the Nagoya University research group, led by Professor Kenichiro Itami, worked on the APEX reaction, a reaction that uses polycyclic aromatic hydrocarbons as models to synthesize nanographenes. Polycyclic aromatic hydrocarbons have three areas of their structure – referred to as the K region, M region, and bay region – which can be elongated in an APEX reaction, producing three nanographs.

These nanographenes can then be further extended in a second reaction, which means that a large number of nanographenes can be synthesized from a single model polycyclic aromatic hydrocarbon molecule.

With Professor Itami’s group having already developed the K region APEX reaction, and another group of scientists having done it for the Bay region, they turned their attention to the M region. They activated the M region to using the 1950 Nobel Prize winner Diels-Alder reaction and successfully performed an elongation reaction on the activated M region, thus making the three possible sites on polycyclic aromatic hydrocarbons capable of synthesizing nanographs .

The researchers were able to produce 13 nanographs with three APEX reactions, most of them being new structures, thus proving both the efficiency and the usefulness of this new method.

This exciting new research and its potential to accelerate the creation of nanographene libraries is a step towards the development of the next generation of materials, which have the potential to revolutionize semiconductors and solar energy and improve lives everywhere. in the world.



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