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Mirror Mirror: A New, Sustainable Way to Make C-N Bonds

Fall 2016

Chemists are in the business of transformation. Whether understanding the fundamental reactions that govern the universe or building complex materials from simple building blocks, our ability to manipulate matter is central to our work. In particular, transformations involving the elements of life—mainly carbon, hydrogen, and nitrogen—are critical to the development of pharmaceuticals and valuable materials.

In a recent study, helmed by Caltech Professors Jonas Peters and Gregory Fu, researchers described a new, cleaner way to make carbon-nitrogen bonds, a common atomic connection in biology and chemistry. The selective synthesis of these fundamentally important molecules, called amines, represents a breakthrough for chemistry powered by visible light.

Previously, rare and sometimes toxic molecules initiated these reactions (chemists call these initiator molecules “catalysts”). Iridium and ruthenium, two of the most popular elements used for these catalysts, together make up only 0.00000014% of the earth’s crust! To make matters worse, multiple catalysts were required in each reaction.

The new method utilizes only one catalyst, made from simple materials and copper. Copper is relatively abundant and non-toxic. Additionally, only 1% of the catalyst is needed to achieve a complete, selective transformation.

To make matters more complicated, most molecules of biological importance exhibit a property known as “chirality,” or “handedness.” Simply put, a molecule and its mirror image can have dramatically different properties inside your body! Let me prove it to you: next time you meet someone new, try shaking hands with your left hand. Aside from giving rise to an awkward situation, you’ll learn a valuable lesson; no matter how you wiggle or contort, you can’t make your left hand look like your right hand, even though they are mirror images. And only right hands fit together properly to shake, just like the molecules inside your body.

In addition to being cleaner and easier, the new amine synthesis has a knack for creating molecules of only a single mirror image. Professor Fu elaborates: “We anticipate that this new method for the synthesis of amines as single mirror-image compounds could have an impact on pharmaceutical research, since amines are common subunits in bioactive compounds, and modern drugs are almost always marketed as single mirror-image molecules. The development of new ways to manufacture compounds can lead to decreased consumption of resources, including energy, and to diminished waste streams.”

With discoveries such as this one, we are reminded that there is still much to learn about the fundamental processes of chemistry. We continue to innovate with the goal of developing sustainable solutions to our most pressing problems

For more information see:
Asymmetric copper-catalyzed C-N cross-couplings induced by visible light
Copper Shines In Asymmetric Amine Synthesis
Visible blue light induces copper-catalyzed C-N cross-couplings

Bryan Hunter

About the Author

Resnick Fellow Bryan Hunter works in Harry Gray's lab developing innovative techniques to gain insights into catalysts for electrocatalytic water splitting for sustainable conversion of solar energy into storable fuels.