Why Click Chemistry Won the Nobel
By Chandana Valaboju | 30 September 2024
Picture this: it's the 1990s. Scientists are trying to figure out a way to make compounds and materials easily without resorting to highly specific reaction mechanisms, catalysts and reagents. Why? Well, the more specific it is, the more difficult, costly and time consuming it would become. A chemist named K. Barry Sharpless figured that it would be beneficial to somehow come up with a streamlined process, where each compound could be made using a limited set of highly robust and efficient reactions. He suggested a bunch of reactions (click reactions), out of which 1,3-dipolar cycloaddition reaction between azides and alkynes turned out to be the most potent as of now.
However, the reaction itself was difficult to achieve. The rates were low at ambient temperature (which is undesirable), and azides are often explosive in nature, which discouraged industrial companies to produce it. This changed when Morten Meldal and Christian W. Tornoe discovered that active copper-species can be used as a catalyst, which increased the reaction rate by upto 10^7 times!
Copper is a toxic substance for human beings, and hence another hurdle arose for cycloaddition click reaction to be carried out in human beings. Enter Carolyn R. Bertozzi, who devised a new way to initiate it - SPAAC (strain-promoted azide-alkyne cycloaddition), that is, copper free click chemistry. Bertozzi and her team showed that SPAAC reaction involving a substituted cyclooctyne structure (cyclooctyne, by itself, is heavily strained) and azides proceeded as expected (without the use of copper). Now, the reaction has been fine-tuned to be used in living creatures.
The joint effort of all these people created something which can very much be used by human beings and improve their lives, which fetched them the Nobel Prize in Chemistry in 2022.
References:
- Olof Ramstrom. (2022, October 5). Scientific Background on the Nobel Prize in Chemistry 2022, CLICK CHEMISTRY AND BIOORTHOGONAL CHEMISTRY. The Nobel Committee for Chemistry
- Image: American Chemical Society