Light and nickel share a unique bond as chemical catalysts for potential new drugs. Princeton University chemists studying photoredox catalysis and nickel catalysis have discovered that bringing the two processes together enables reactions that neither could produce on its own. Pairing photoredox and nickel catalysts bonded multiple traditionally unreactive coupling partners, the researchers said. Specifically, the photoredox catalyst — which is activated by LEDs or other lights — transforms common carboxylic acids in a molecule into reactive sites. The nickel catalyst then couples those sites to arenes, ring-shaped molecules frequently present in drug candidates. A carboxylic acid (left) reacts with an aryl halide (right) in the presence of tiny amounts of a photo catalyst and a nickel catalyst to form a direct bond between two highly prevalent classes of molecules. Courtesy of Science/AAAS. This bond formation could provide a shortcut for chemists as they construct and test thousands of molecules to find new drugs. “I think it's remarkable that you can have two catalysts in the reaction, both performing the roles that they're best at and yet are still compatible with one another,” said Princeton chemistry professor Dr. Abigail Doyle. The researchers said they have used their reaction to make more than two-dozen products in high yields. The work was supported by grants from the National Institute of General Medical Sciences, Merck, Amgen, Eli Lilly and Roche, and by postdoctoral fellowships from the Shanghai Institute of Organic Chemistry. The research was published in Science (doi: 10.1126/science.1255525). For more information, visit www.princeton.edu.