Milestone for organic chemistry: Long searched chemical compound prepared for the first time

Chemists report on the "neutral homoaromatic compound" that has only been suspected for more than 70 years

17-Apr-2023 - Germany

In a recent issue of the international journal Nature Chemistry, Prof. Dr. Johannes Teichert, head of the Professorship of organic chemistry at Chemnitz University of Technology, his research assistant Trung Tran Ngoc, and other contributors report on a so-called "neutral homoaromatic compound".

The findings are a milestone for organic chemistry, as chemists had only proposed the existence of this class of molecules for more than 70 years. Practical evidence had been lacking until now.

"With this groundbreaking discovery, we were able to solve a fundamental problem in chemistry and demonstrate for the first time, that the long-assumed but never prepared neutral homoaromatic compounds actually exist in organic chemistry", says Teichert. "This is nothing less than a breakthrough for organic chemistry – also because we have characterized these compounds for the first time with their individual properties", Teichert continues.

The homoaromatic molecules produced by Teichert and his team can, for example, be used as "replacement building blocks" for classical aromatic molecules. This opens up entirely new combination possibilities and approaches for developing new materials or active substances in medicine.

First stable synthesis and targeted modification

While classical aromatic molecules are characterized by their cyclic structure and a circular movement of electrons, this ring is interrupted in homoaromatic compounds.

However, if the reactive ends of the molecule are held in an exact geometry, the circular movement of the electrons is maintained even without a "real" bond. This connection of molecules beyond a classical chemical bond is a special property of the homoaromatic compounds produced by Teichert and his team. "For the first time, we can now investigate and systematically modify the molecular interactions within the homoaromatic compounds," adds Teichert's assistant Trung Tran Ngoc. "The stability of the compound allows us to intensively explore and better understand the concept of homoaromaticity," Teichert adds.

New photochemical switches enable new research paths, e.g., in biomedicine

With the discovery of this new form of chemical compounds, a new type of photochemical switch is also introduced. So-called "photoswitches" play an important role in medicine and biomedicine, among other fields. These switches can, for example, be used to specifically stimulate active substances in the human body from the outside using light, activating and investigating their effects on-site.