Yudu - Nanotimes September 2011

nanotimes News in Brief

11-09 :: September 2011

Engineering // Electric Motor made from a Single Molecule

hemists at Tufts University‘s School of Arts and Sciences (U.S.) have developed the world‘s first single molecule electric motor.

The Tufts team reports an electric motor that mea- sures a mere 1nm across, groundbreaking work considering that the current world record is a 200nm motor. A single strand of human hair is about 60,000nm wide.

“There has been significant progress in the construc- tion of molecular motors powered by light and by chemical reactions, but this is the first time that electrically-driven molecular motors have been demonstrated, despite a few theoretical proposals,” says E. Charles H. Sykes, Ph.D., associate professor of chemistry at Tufts and senior author on the paper. “We have been able to show that you can provide electricity to a single molecule and get it to do some- thing that is not just random.”

Sykes and his colleagues were able to control a molecular motor with electricity by using a state of the art, low-temperature scanning tunneling micro- scope (LT-STM), one of about only 100 in the United States. The LT-STM uses electrons instead of light to “see” molecules. The team used the metal tip on the microscope to provide an electrical charge to a butyl methyl sulfide molecule that had been placed on a conductive copper surface. This sulfur-containing

The molecular motor was powered by electricity from a state of the art, low-temperature scanning tunneling microscope. This microscope sent an electrical cur- rent through the molecule, directing the molecule to rotate in one direction or another. The molecule had a sulfur base (yellow); when placed on a conductive slab of copper (orange), it became anchored to the surface. The sulfur-containing molecule had carbon and hydrogen atoms radiating off to form what looks like two arms (gray); these carbon chains were free to rotate around the central sulfur-copper bond. The researchers found that reducing the temperature of the molecule to five Kelvin enabled them to precisely impact the direction and rotational speed of the mole- cular motor.