MIT’s Richard Schrock and colleagues at Boston College have achieved a significant advance in chemistry: catalysts that produce molecules in only one of two possible mirror-image forms known as right- and left-handed. By fine-tuning molecular structures to an unprecedented degree, the new catalysts could lead to safer, more effective pharmaceuticals, as well as new plastics, synthetic fibers, and fuels.
Schrock, the Frederick G. Keyes Professor of Chemistry, shared the 2005 Nobel Prize in chemistry for explaining how catalysts induce a powerful, efficient, and environmentally friendly chemical reaction called olefin metathesis, which transforms simple molecules into complex ones. But until now, chemists have not succeeded in developing catalysts that can create a broad range of organic compounds through this type of reaction.
Schrock’s new molybdenum-based catalysts “seem to have significantly different properties than all of the catalysts we’ve been working with for the past 20 years,” he says. “They produce 10 times more product per unit of catalyst.” What’s more, they can be prepared in numerous variations that may suit different applications.
While chemicals found in nature are usually either right- or left-handed, chemical synthesis typically produces the left-handed and right-handed versions in equal quantities. That’s a problem, because the two forms may work completely differently but are almost impossible to tell apart. The left-handed version of the drug thalidomide, for example, is a powerful tranquilizer, while the right-handed version causes severe birth defects. With the new catalysts, chemists can make almost entirely pure batches of left-handed or right-handed molecules.
The new catalysts will enable chemists not only to make known compounds with precision but also to arrange chemical building blocks into thousands of new configurations, with potential applications ranging from new fabrics and polymers to new drugs and synthetic fuels. “It’s like being back in the playground,” Schrock says. “You can have fun making new things.”