Dr. David MacMillan, who earned his Ph.D. in chemistry from UCI in 1996, was awarded the 2021 Nobel Prize in Chemistry for his research on the development of asymmetric organocatalysis by the Royal Swedish Academy of Sciences on Oct. 6.
MacMillan shares the recognition with Dr. Benjamin List, a German professor at the Max-Planck-Institut für Kohlenforschung, who collaborated with MacMillan on organocatalysis research.
Asymmetric organocatalysis is the chemical process of using a catalyst that does not have a mirror image of itself, producing a variety of asymmetric molecules instead.
Symmetric catalysts, those that have mirror images of themselves, sometimes possess different functions while looking the same in appearance, which makes them more difficult to use. Asymmetric organocatalysis successfully utilizes asymmetric catalysts, which will provide chemists with only one necessary structure in a simple and straightforward way.
Understanding catalysts are crucial to understanding the importance of these molecules. In chemistry, catalysts play important roles in the facilitation of a chemical reaction. As substances that can increase the rate of a reaction without actually becoming a part of the reaction itself, catalysts can lower the amount of energy required to begin reactions.
While catalysts have become a fundamental tool for chemists, only two groups of catalysts have been known in the field of chemistry in the 20th century: metals and enzymes.
Transition metals possess the ability to lend or withdraw electrons from any reagent during a chemical reaction. This allows for bonds between atoms in a molecule to lose strength, causing them to break existing bonds or form new ones. Enzymes, on the other hand, are proteins found in all living organisms. With similar abilities as metals, enzymes help build and break substances in our bodies and are obtained either from food or are naturally synthesized.
In hopes of improving asymmetric catalysis with metals in 1998, MacMillan paved the way for the discovery of a third type of catalyst in chemistry by the year 2000: asymmetric organocatalysts.
When List and MacMillan were working independently during the 2000s, MacMillan noted that metal catalysts were not used extensively in industrial processes. MacMillan believed that this was due to how expensive and difficult utilizing these substances had already been, and he aimed to look for ways to simplify this process with a more durable catalyst.
MacMillan utilized simple organic molecules to design what he was looking for. Most organic molecules are structured around hydrocarbon chains and rings, where active chemical groups such as oxygen and nitrogen can be added to create more complex molecules. Another key idea MacMillan had in mind was that organic molecules also have the ability to facilitate the donation or withdrawal of electrons, like metals.
In order for the chemical reaction to run, the organic molecules being synthesized would have to include the element nitrogen to form an iminium ion. This would allow MacMillan to test a Diels-Alder reaction, a conjugate addition reaction that would produce a six-membered carbon ring.
When MacMillan finished, he became successful in creating the first asymmetric organocatalyst in the field of chemistry.
Over the years, the application of asymmetric catalysis has significantly shaped the world of science. In the pharmaceutical industry, organocatalysts have helped create pharmaceuticals that are safe and effective to use on humans. Since symmetrical molecules can have differing functions that may be the origin of negative effects on various body systems, having molecules that differ in structure appearance will aid the distinction between harmful and beneficial products.
As a current professor at Princeton University, MacMillan was congratulated by the institution on the day the Royal Swedish Academy of Sciences announced their awardees. During Princeton’s news conference on the same day, MacMillan reflected on what this award would mean for the future of science.
“Everything that we do, or what a chemist does, impacts everything that’s around us all of the time and is immediately in front of us,” MacMillan said. “It is unbelievably exciting to be involved with a science that what you do on a Tuesday can have an impact on a Friday. As long as we keep maintaining that focus and drive to have an impact, I think we’ll all hopefully be in … good shape going forward.”
Korintia Espinoza is a STEM Intern for the fall 2021 quarter. She can be reached at firstname.lastname@example.org.