Young scientists from the Institute of Physical Chemistry and Electrochemistry. A.N. Frumkina, together with colleagues from the Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, as well as from the Moscow State University. M.V. Lomonosov have developed a method for obtaining conducting nanostructures (“nanowires”), which allows you to solve all these problems. The article was published in the journal Inorganic Chemistry. The authors use the ability of organic molecules to spontaneously, the so-called supramolecular assembly using weak intermolecular bonds that hold molecules together due to a large number of contacts. It is this principle that underlies the self-assembly of complex biological objects: membranes, cells, tissues.
The nanowires were assembled from ready-made supramolecular blocks 2 nm in size synthesized from phthalocyanines – synthetic dyes of cyclic structure with semiconducting properties and widely used in organic electronics. Crown ether groups (cyclic molecules-“traps” for metal cations) were added to the phthalocyanines and coupled together in pairs with rare-earth ions. Despite the complexity of the molecular structure of an individual block, the process of obtaining nanowires from them is very simple – it is enough to add a potassium salt to them. Potassium cations bind to crown ether traps of neighboring blocks and collect them in one-dimensional stacks up to 100 microns in length. Such nanowires are practically free of defects and conduct electric current 50 times more efficiently than other known materials based on phthalocyanines.
The simplicity of the method opens up the possibility for its adaptation to the real production of new compact optoelectronic devices. “In order to connect the elements of an electrical circuit in a device for organic electronics, it is necessary to be able to lay nanowires in the desired configuration on the surface of a silicon chip,” says Alexandra Zvyagina, head of the Russian Science Foundation grant for young scientists, within the framework of which this work was carried out (Grant No. 19- 73-00025). “We found that our nanowires align themselves along the lines of force in an external electric field, and due to this effect, we easily and quickly get films with nanowires laid on the surface in a given direction.”
Self-assembly and orientation in an electric field are not all the advantages of supramolecular nanowires over traditional conductive polymers. The comparative “weakness” of bonds between molecules in nanowires becomes their strength, allowing one to solve one of the most difficult problems of modern chemistry, associated with the prevention of the release of microplastics into the environment during the disposal of polymers. Scientists from the Institute of Physics and Chemistry of Economics of the Russian Academy of Sciences have shown that ready-made supramolecular nanowires, which are stable under normal operating conditions of electronic devices, can be quickly disassembled to the original molecules in a special solvent without the formation of by-products that could damage the environment. The technology makes it possible to preserve valuable compounds containing rare earth metals in the process of recycling a spent chip and use them again to assemble a new device. Young researchers are confident that technologies based on supramolecular assembly can provide future progress in the field of “green” waste-free microelectronics, and conductive nanostructures obtained using this technology will become a reliable alternative for difficult-to-decompose conductive polymers.
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