In a paper published in the Journal of the American Chemical Society, the scientists explain that their proposed technique allows them to perform what is known as a cross-coupling reaction, where two molecules are joined by a carbon-carbon bond. This is one of the most widely used reaction types and is essential for making most of the chemical products used today.
Using copper as a catalyst for cross-coupling reactions is a breakthrough in sustainability, the researchers said, as such reactions typically rely on the use of precious metals such as palladium.
The new method is also considered advantageous because the copper in the molecular catalyst itself absorbs blue light, rather than requiring a separate light-absorbing compound outside the catalyst. This makes synthesis not only cheaper and simpler, but also easier to control because there are fewer moving parts.
Blue light plays a key role in the activation of copper-based catalysts. Theoretical calculations show that this light exposure causes electrons to move from the metal copper atoms to a connected subunit of the molecular catalyst. This excited state separates the charge and makes the catalyst more reactive, so researchers are able to use it for cross-coupling reactions to form acyl groups, which are useful for synthesizing drugs and optoelectronic materials.
A key aspect of this method is the asymmetric formation of acyl groups. This means that one of the two possible mirror versions of the product molecule is selectively produced, a highly desired property for new drug development.
The implementation of this new approach promises both cost savings and increased sustainability in the production of a variety of compounds with potential uses in medicine and electronics.
Yusuke Masuda, lead author of the study, said in a media statement: "This synthesis method is a breakthrough because it combines two readily available substances, blue LED light and copper, to achieve a coupling reaction that did not exist before. Technologies to produce useful compounds from the Earth's abundant resources are essential for sustainable human development. I anticipate that this progress will be a milestone in the development of sustainable molecular synthesis methods.
