The Laboratory of Multiscale Modeling of Multicomponent Functional Materials of South Ural State University employs specialists in the field of quantum chemistry. They are studying the properties of materials of the future, which are now only at the development stage.
One of the modern trends in the design of materials is materials based on metal-organic frameworks (MOF, or MOF from the English metal organic framework). They are built from separate structural blocks and due to this are capable of manifesting a combination of properties, for example, flexibility and luminescence, sorption and electrical conductivity.
«Children like to play with construction sets, where there are different blocks, sticks, balls», says Irina Yushina, a researcher at the SUSU Research Laboratory of Multiscale Modeling of Multicomponent Functional Materials. «And our construction set consists of structural blocks, which, depending on how they are connected, are «assembled» into a frame of different structures. By changing the central metal or binder blocks, you can control the structure, and therefore the properties of the resulting framework».
For example, the nickel-based organometallic framework DUT-8 (named after the Dresden University of Technology), whose properties are studied by Irina Yushina, is remarkable for the fact that it can work as a box with a lock for packaging molecules. Under normal conditions, the pores are open and can contain various molecules, but under external influence, on the contrary, they click. This reversible transition from the open to the closed phase allows you to control the sorption and retention of molecules in the pores.
«Many of the materials that are now being actively implemented in the technology started with the earliest stages of obtaining, modeling the structure and screening potential areas where this compound could be useful. And then engineers come to the aid of experimental chemists and theorists», says Irina Yushina. – Of what has already been implemented, probably the most famous example is a water regenerator in the desert. It is implemented in the form of a portable device with a cartridge containing MOF, and is capable of extracting up to 200 g of water per 1 kg of the frame per day, according to the journal Nature Water. Pores trap water molecules, retain them, and due to temperature fluctuations in the desert, water is regenerated from the pores. This technology can really be used to solve the problems of water scarcity, and it began simply with the fundamental study of sorption».
Irina Yushina and her colleagues study not only phase transitions, but also the mechanics of flexible metal-organic frameworks – MOFs. They conduct computational experiments, including with the involvement of the Tornado-SUSU supercomputer. The result is stress tensors of «molecular structures» at the level of crystals, which can be compared to the calculations of the strength of houses that builders make. The approaches and phenomena are similar, but the scales and methods are completely different.
However, the SUSU team focuses not only on the mechanical properties of frameworks capable of changing shape, but also on the use of crystals based on organometallic frameworks in nonlinear optics.
«The task of such a crystal is to convert the wavelength of laser radiation, thereby expanding the list of available laser wavelengths: from violet to long-wavelength», explains Irina. «If a crystal has certain structural characteristics, then it is possible to record such an effect in an experiment, but the answer to the question of whether this structure potentially has the desired property without conducting an experiment can be given by quantum chemical modeling».
The results of the research of Irina Yushina and her colleagues were published in the international journals Crystal Growth & Design (Q1 Scopus) https://doi.org/10.1021/acs.cgd.3c01154 and Advanced optical materials (Top 10%) https://doi.org/10.1002/adom.202300881