Notes from the Back Row: "Making Molecules"

"I grew up cooking, waiting tables, and doing dishes in the family diner in Chicago," says Jonas Peters. These days, as Caltech's Bren Professor of Chemistry, Peters is more an executive chef than a spatula jockey: he coordinates the menu and helps dream up the recipes for new molecules, but his students whip them up and wash the glassware. In his Watson Lecture on March 14, 2012, Peters leads a cook's tour of the art and science of chemistry. In his words, "What holds molecules together? How do we design one, plan the recipe, and know how well it came out?"

"The craft of making molecules hasn't changed that much" since the days of the alchemists, says Peters. "Take of cranium humanum as much as you please," he says, quoting a recipe from John French's The Art of Distillation, written in 1651. "Break it into small pieces, which put into a glass retort well luted [sealed airtight], with a large receiver well luted. Put a strong fire to it by degrees, continuing of it until you see no more fumes come forth, and you shall have a yellowish spirit, a red oil, and a volatile salt. Take this salt and the yellow spirit, and digest them by circulation two or three months in balneum [in a hot bath], and you shall have a most excellent spirit." While this extract is no longer the remedy of choice for dropsy—whatever that is—its method of preparation will be familiar to anyone who spent some time in the chem lab in high school. 

On the other hand, the theory behind making molecules has advanced considerably, allowing modern chemists to create very complex arrangements of atoms by design. Peters's own lab, for example, contributes to Caltech's Joint Center for Artificial Photosynthesis, an initiative to develop the technologies needed to run our civilization entirely on sunlight. We are still a long way from that happy dawn, but we are well beyond another piece of advice from alchemist John French, who counseled the uninitiated to "try not at first experiments of great cost or great difficulty, for it will be a great discouragement to you, and you will be very apt to mistake." At Caltech, notes Peters, "we have fantastic grad students and postdocs, so we can dive right in and do experiments of great difficulty knowing they can pull it off."

"Making Molecules" is available for download in HD from Caltech on iTunesU. (Episode 10)