World first microscopic race


Rebecca Pool

Friday, May 12, 2017 - 11:30
Image: Six teams from three continents entered the nanocar race.
Researchers from the Universities of Rice and Graz have won the world's first Nanocar Race, at CNRS, Toulouse, France, with a molecular vehicle called Dipolar Racer.
Six teams from three continents entered the unique race in which nanocars - including Dipolar Racer, Ohio Bobcat Nano Wagon and Swiss Nano Dragster - were steered along either a polished gold or silver track, within scanning tunnelling microscopes.
The Toulouse laboratory is home to a set of novel STMs including an instrument with four tungsten scanning tips.
This mean't four of the competitors could race their specially-designed vehicles at the same time, using electric impulses generated by the tips of the instrument.
STM images of the some of the nanocars.
"We chose our fastest wheels and our strongest dipole so that it could be pulled by the electric field more efficiently," explains Rice University chemist, Professor James Tour. "We gave the vehicle two, side-by-side, wheels to minimise interaction with the surface and to lower the molecular weight."
The Dipolar Racer designed at Rice.
But as Tour's colleague and physicist, Leonhard Grill from the University of Graz, points out, the race wasn't without its hitches.
"Gold had been the surface of choice so we tested this and it turned out to be too fast," highlights Grill. "It was so fast we couldn't even image it."
So instead the researchers got permission to use a slower silver surface within a single-tip STM, but with an additional handicap.
"We had to go 150 nanometres around two pylons instead of 100 nanometres as our car was so much faster," says Tour.
Rice and University of Graz run fastest single-molecule car in international event.
Dipolar Racer's top speed came in at 300 nm an hour, with the nanocar averaging 95 nm around its 150 nm track.
The nanocar finished the race in just one and a half hours; the overall race was declared over after thirty hours.
Swiss Nano Dragster, designed by Professor Ernst Meyer from the Nanolino Lab at the University of Basel, finished next, five hours later and was declared a co-winner as the vehicle came first amongst those racing on a gold track within the four-tip STM.
According to the race organisers - the French National Center for Scientific Research, CNRS, - the aim of the competition was to push the science of how single molecules can be manipulated as each interacts with a surface.
"This is the beginning of our ability to demonstrate nanoscale manipulation with control around obstacles and speed, and will pave the way for much faster  paces and eventually carrying cargo and doing bottom-up assembly," says Tour.
The silver track under the microscope: Two Rice nanocars are in the blue circle at top. The lower car was the first to run the race, finishing in a 1½ hours. The top car was put through the course later, finishing in 2 hours.
The Dipolar Racer was built using low adhesion molecular wheels, alkynyl axles, aryl chassis, and dipolar functionalities front and rear. Sonogashira cross coupling reactions were used to accomplish the assembly.
Meyer and colleagues used the molecule 4'-(4-Tolyl)-2,2':6',2''-terpyridine, for the Swiss Nano Dragster. The simple and robust molecular structure had no wheels, acting as a hovercraft rather than a car.
The motion of the Swiss Nano Dragster was in principle almost friction-less due the weak interactions between the carbon-based molecule structure and the race track. 
Learn about all the cars here.
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