This year’s Nobel laureates in chemistry developed the world’s smallest gadgets: motors, machines, and even vehicles made not from metal and electronics but from molecules. The prize is shared equally by Jean-Pierre Sauvage of the University of Strasbourg in France, Fraser Stoddart of Northwestern University, Evanston, in Illinois, and Bernard Feringa of the University of Groningen in the Netherlands, "for the design and synthesis of molecular machines."
It has been a dream of scientists for more than half a century to shrink machines down to the scale of billionths of a meter, or nanometers, Sara Snogerup Linse, chair of the Nobel Committee for Chemistry, said at a press conference in Stockholm this morning. But they needed to develop new chemical strategies to make interlocking ring molecules and find a way to convert energy into work—in other words, construct a molecular motor—all at a size one-thousandth that of a human hair.
Sauvage and his group made the first breakthrough in 1983 by developing a way to interlink molecular rings. Taking a ring molecule and one crescent-shaped molecule and sticking them together with the help of a copper ion, they would then attach another crescent onto the first, to make a new ring interlocked with the first one. Remove the copper glue and they could move freely around, joined only by being intertwined. Such a chainlike molecule is known as a catenane and Sauvage's team later developed ways to control the rings' rotation through each other.
In 1991, Stoddart’s group made another breakthrough: a molecular shuttle. They developed a way to latch a ring-shaped molecule around another long molecule in a way that it could move freely along the molecule between two blocking “stations.” By 1994, Stoddart’s team had developed a way to control the shuttle’s movement along the molecular track—together known as rotaxane—and used the technique to make a molecular elevator and a molecular muscle.
Feringa made the next major advance in 1999, with a molecular motor. Taking a molecule with two components linked by an isomer-isomer bond, his team could make one component rotate by 180° with a pulse of ultraviolet light, and make it rotate another half-turn in the same direction with another pulse of light. Soon they had the rotor spinning at 12,000 revolutions per second and demonstrated its strength by rotating a microscopic glass rod that was 10,000 times the size of the molecular motor.
In a final tour de force, they constructed a molecule with a motor at each of four corners—a nanometer-sized, four-wheel-drive car that could be seen driving across a surface. Feringa discussed it in this video produced by his university:
The key to the work, Stoddart says, was the development of a new type of chemical bond, a mechanical linkage that allows components to interact in a controlled and repeated manner. “It’s a new bond in chemistry. That’s revolutionary in this field,” he says. Chemists produce perhaps thousands of new compounds every day, Stoddart says, and they come up with one or two new reactions every week. “A new bond? That only happens once in a blue moon. This is an advance in fundamental chemistry.”
The Nobel was awarded for basic fundamental science that's still at the development stage, Olof Ramström of the Nobel Committee told the press conference. But he compared the laureates with scientists of the early 19th century who made the first electrical machines and started a revolution that we are benefiting from today. “The future will show what sort of machines will come out of this,” he said.
“It’s a bit early days, of course, but once you are able to control movement, all sorts of things are possible,” Feringa told the press conference by phone. "Think about tiny little robots that the doctor would inject into your bloodstream, and that would go search for a cancer cell or deliver a drug." He compared his work to that of the Wright brothers, who could not possibly have imagined today's aircraft.
Given the current concern about nanomaterials escaping into the environment, Feringa was asked whether he had any nightmares about this technology going wrong. "I think we have to think about how we can handle these things safely, but I'm not so worried about that. Once we are able to design these types of micromachines and nanorobots, we will also have the ability to build in all kinds of safety devices," he said, adding that new inventions would be carefully evaluated for safety, just like new chemical and biological agents.
"I don't know what to say and I'm a bit shocked, because it was such a great surprise," Feringa told the reporters when asked for his reaction to winning the prize. "I'm so honored and so emotional about this." For his part, Stoddart too says he was “overjoyed” when he received his 5 a.m. phone call. “I heard voices with Swedish accents and wondered whether this could be a hoax,” Stoddart says. It quickly became apparent that it was the real thing when he was told he was sharing the prize with Sauvage and Feringa. “We’re as thick as thieves,” Stoddart says. “We’ve supported each others’ work for years.”
“All of them definitely deserve it, there’s no doubt about that,” says photochemist Thorsten Bach of the Technical University of Munich in Germany. “The eye opener for me was really the publication by Ben Feringa in the late 1990s about this light-driven monodirectional molecular motor. Then he extended the field significantly, for example when he used it to rotate microscale objects.” Looking further back, Bach says, Stoddart was the first who really started thinking about what you need to make molecular machines. “You need engines, brakes, and gears and all of this.” Although Sauvage provided the fundamental ideas of supramolecular chemistry behind it. “It’s just beautiful that you can really handle and really move something on a molecular level,” he says. “I don’t dare to predict where it is going to lead.”
With reporting by Robert F. Service.