This may be from a high-tech factory, but this line is only a few nanometers long.
The robot moves slowly along the track and pauses regularly to extend the arm that carefully lifts the assembly. The arm connects the assembly to the fine construction on the back of the robot, then the robot moves forward and repeats the process – according to the precise design, the components are strung together in an orderly manner.
This may be from a high-tech factory, but this line is only a few nanometers long. The component is an amino ACID and the product is a small peptide. The robot created by the British University chemist David Leigh is the most complex molecular-level machine ever designed.
This is not a case. Leigh is part of an increasing number of molecular "architects". They were inspired to simulate machine-like biomolecules found in living cells. Over the past 25 years, these researchers have designed an impressive array of switches, ratchets, engines, thrusters, and more – just as they are nanoscale Lego components that can be integrated into molecular mechanics . At the same time, progress is accelerating thanks to analytical chemical tools and improvements in the simpler reactions to build large organic molecules.
"Architect" in the molecular world of mini robots
A molecular "nano car" travels along the metal surface
Creating a molecular shuttle
Many of today's molecular machines can be traced back to a relatively simple device built in 1991 by FraserStoddart, a chemist currently working at Northwestern University. That is a combination called a rotaxane in which a circular molecule is passed through an "axis" and a "axis" is a linear molecule that is blocked by a larger "plug" at both ends. This particular "axis" contains two chemical groups that bind to the cyclic molecule at each end of the chain. Stoddart discovered that the circular molecule can move back and forth between these two points, creating the first molecular shuttle.
In 1994, Stoddart improved the design so that the "axis" had two different binding sites. The molecular shuttle is present in the solution, and changing the acidity of the liquid forces the cyclic molecule to move from one location to another, thereby making the molecular shuttle a reversing switch. Similar molecular switches may one day be used to respond to heat, light or specific chemicals, or to open nano-scale container "hatches" to transport "cargo ships" loaded with drug molecules to the human body at the right time. On the sensor.
Together with James Heath from the California Institute of Technology, Stoddart uses millions of rotaxane to create storage devices. Sandwiched between the electrodes of silicon and titanium, the rotaxane can be switched from one state to another by current switching and used to record data. This molecular "abacus" is about 13 microns wide and contains 160,000 bits, and each bit is made up of hundreds of rotaxane - a density of about 100 gigabits per square centimeter, which is the best commercialization today. Hard drives are comparable.
However, "switches" are not very powerful and usually fall apart after less than 100 cycles. One possible solution is to load them into a hard, porous crystal called a metal organic framework (MOF). Earlier this year, Robert Schurko and Stephen Loeb from the University of Windsor, Canada, confirmed that they were able to pack about 1021 molecular shuttles into a 1 cubic centimeter MOF. Last month, Stoddart revealed a different MOF that contained switch-controlled rotaxane. This MOF is mounted on the electrodes, and the rotaxane can be turned on or off by changing the voltage.
Nano engine
In 1999, after the early molecular shuttle and switch tests, the field took a big step forward with the creation of the first synthetic molecular engine. The molecular engine was built by a team led by chemist BenFering of the University of Groningen in the Netherlands and is a single molecule containing two identical "paddle" elements joined together by carbon-carbon double bonds. The researchers fixed the "paddle" in a position until a beam of light broke part of the chemical bond, allowing the "boat paddle" to rotate. Crucially, the shape of the “pulp†means that they will only turn in one direction, and as long as there is light and some heat supply, the engine will keep spinning.
Feringa continues to use a similar molecular engine to create a four-wheel drive "nano car." He also confirmed that the engine can provide enough rotational force for the liquid crystal to slowly rotate the glass rod above the engine. Glass rods are 28 microns long and are thousands of times the size of the engine.
Some chemists believe that although these engines are cute, they will eventually be useless. "For man-made engines, I have always had doubts - they are too difficult to manufacture and difficult to scale up," said Dirk Trauner, a chemist at the University of Munich in Germany.
However, the chemistry behind them may be useful. Using the same light activation mechanism, the researchers developed about 100 drug-like compounds that can be turned on or off depending on the response to light.
Trauner and Rachel Klajn, a chemist at the Weizmann Institute of Science in Israel, believe that the main challenge will be to convince the cautious pharmaceutical industry to believe that these light-controlled drugs have great potential, even if they have not been tracked in humans. "Once they see the value, we will be in a good state."
Two different development directions
In the search for molecular machines that can do something useful, researchers are beginning to integrate a number of different components into a single device. In May of this year, Stoddart announced an artificial molecular pump that "pulls" two cyclic molecules out of solution onto a storage chain. Each circular molecule is placed over a "plug" at one end of the chain and is attracted by a switch-controlled junction. The rotary switch pushes the circular molecule across the second barrier further away from the storage chain, where the circular molecules reach the waiting zone.
This system was unable to transmit any other type of molecule and was successfully built after repeated attempts to correct it. “This is a long road,†Stoddart exclaimed. However, it confirms that molecular machines can be used to agglomerate molecules and push the chemical system into a non-equilibrium state in the same way that biologically forces ions or molecules to form concentration gradients to create rich potential energy. “We are learning how to design an energy ratchet.â€
Stoddart also said that such results can lead the field in two main directions: to maintain the molecular-level tasks that these machines can't achieve by any other means at the nanometer scale; or to develop in a macro direction while using the trillions of units. Machines transform materials or move large quantities of goods, just like a large group of ants.
Perhaps the best example of a nanomethod is Leigh's molecular pipeline. Inspired by ribosomes, it is based on a rotaxane system that picks up amino acids from the "axis" and adds them to the growing peptide chain. However, this device may have a macro application. In 36 hours, 1018 units working together can produce a few milligrams of peptide. "It can't do things that you can't do in the lab for half an hour," Leigh said, but it confirms that you can have a piece that moves down the track, picks up the "building blocks" and combines them in The machine together. Currently, Leigh is working on other versions of the machine to create a segmented polymer with tailored properties.
On the contrary, the trillions of molecular machines that work together can also change the material properties of the macro world. For example, a gel that expands or contracts in response to light or chemicals can act as an adjustable lens or sensor. "In the next five years, I bet you will get the first smart materials that contain switches," Feringa said.
Concerned about surprises
Acetic Acid is a colourless liquid organic compound with the chemical formula CH3COOH . When undiluted, it is sometimes called Glacial Acetic Acid. As one of most important organic raw materials, it is mainly used in vinyl acetate, acetic anhydride, acetate ester, acetate, acetate fiber and chloroactic acid etc. It is an important raw material for syntesized fiber, gooey, medicines, pesticides and dyes, and also a good organic solvent. It is widely applied in industries of plastics,printing and rubber etc.
Appearance:
transparent liquid; Pungent odor,miscible with water,alcohol,ether and carbon tetrachloride; insoluble in carbon disulfide.Use :
As one of most important organic raw materials, it is mainly used in such products as Vinyl acetate, acetic anhydride, diketene, acetate ester, acetate, acetate fiber and chloroactic acid etc. It is an important raw material for synthesized fiber, gooey, medicines, pesticides and dyes, and also a good organic solvent. It is widely applied in such industries as of plastics, rubbers and printing etc. Manufacture of acetic anhydride, vinyl acetate; Widely used in solvents, dyes, celluloseacetate, pharmaceuticals, in-socticides, textile printing, photographic film and coagulating rubber tec.
Acetic Acid,Acetic Acid Glacial,Glacial Acetic Acid,Acetic Acid Industry Grade
Yucheng Jinhe Industrial Co.,Ltd , https://www.jinhetec.com