Nanomachine Racing

The broadcast of the first ever molecular races has begun

Vladimir Korolev, N+1

At 12:00 Moscow time, the first ever molecular race started in French Toulouse (details are available on the Nanocar Race website). Molecules or supramolecular complexes act as racing cars – their size is tens (and sometimes hundreds) of thousands of times smaller than the cross section of a hair. Especially for racing, the National Center for Scientific Research (CNRS) has developed a scanning tunneling microscope with four reading elements at once. The total length of the race route is 100 nanometers, including two 45-degree turns. Six teams from Japan, France, Germany, Switzerland and the USA will participate in the race. The event is broadcast online on the official channel of molecular racing on Youtube. The race will last 30 hours.

Molecular machines are molecules, or groups of molecules, capable of performing certain operations in a controlled manner. For example, under the action of light quanta, they can rotate individual parts or move them like a piston in a pump under the action of chemical additives. In 2016, the Nobel Prize in Chemistry was awarded for the development of molecular machines, you can read more about it in our material.

Molecular machines participating in the races are able to move directionally on metal surfaces under the influence of an electric current. The track (more precisely, four tracks) it is located on the surface of an 8 mm gold medallion. It is a curved groove, 0.3 nanometers deep (about two gold atoms occupy such a space) and 100 nanometers long. According to the rules of the race, the time allotted for overcoming the route is 30 hours. In case of an "accident", the car is allowed to be replaced, but it is forbidden to change the needle during the race.

A total of six teams participate in the race. Initially, it was planned to select four finalists, but, as the organizers noted in the commentary to the broadcast, "they are not so heartless" as to disqualify two teams ready to participate. Therefore, all six teams participate simultaneously, four – controlling a four–probe microscope in CEMES (Toulouse), two more - remotely controlling two more microscopes in the USA and Europe.

In the first stage, participants must place molecular machines on their part of the medallion. Initially, machines are ordinary powders or exist in the form of solutions, in one gram of such material there can be hundreds of billions of billions of molecules. Machines can be placed on the medallion either by sublimation (evaporation and then deposition on a golden surface) or by precipitation from a solution.

The installation in which the molecular races will take place
Cyril FRESILLON/CEMES/CNRS

Then, using a scanning tunneling microscope, the teams must place one of the cars at the beginning of the track. This type of microscopes is a very sharp needle (there may be only a few atoms on its tip), with which you can feel the surface of the sample by applying voltage to it and measuring the electron tunneling current. The uniqueness of the microscope used in racing is that four such needles work in it simultaneously and independently.

The movement of molecular machines along the track, according to the rules of the race, must take place under the action of electrical impulses. The machine cannot be pushed mechanically with a needle. At the same time, the principle of movement of "sports cars" may be different, but, as a rule, the molecules change their geometric configuration due to the energy from the electron that fell from the needle. The speed of the machines corresponds to about 0.3-0.6 nanometers for each electrical pulse. The main difficulty is the need to track the position of molecules on the track, one scan can take several minutes. 

The idea of the contest arose in 2013 when analyzing scientific publications of various groups. In total, nine projects submitted applications for participation in the races, six of them met the necessary criteria. Information about the teams' molecular machines is published on the event's website. So, the French team created a "green buggy" for participation – a flat elongated molecule, flanked by four wheels, each of which looks like a screw with three blades. The "green" in the name is a reference to the color of the substance solution. The molecule of the Swiss team is rather an analogue of the "hovercraft" – the tolylterpyridine molecule is devoid of wheels and moves along the surface due to weak interactions with it. The team from Germany uses instead of one molecule a complex of four particles connected by weak hydrogen bonds at once – a "turntable".

The organizers note that the main goal of the races – in addition to the competition between scientific groups – is to improve the methods of observing single molecules and controlling their movement.

Portal "Eternal youth" http://vechnayamolodost.ru  28.04.2017