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Scientists from St. Petersburg State University and Tomsk Polytechnic University applied the key-lock concept developed in the 19th century to complex inorganic molecules - polyoxometallates (POMS) — and found that compounds of iodonium cations can be a "key" for them, triggering selective interaction between ions. Thanks to this, it is possible to create materials with specified properties and new catalysts. The results of the study are published in the flagship scientific journal of the Royal Society of Chemistry, Chemical Science.

The interaction of enzymes and substrates in chemistry was described by the German scientist Emil Fischer in 1894. Fischer noticed that enzymes (biological catalysts) interact with their substrates (the molecules they affect) in a very specific way. He compared this interaction to a key that fits only a certain lock. This analogy helped explain why enzymes are so selective in their work. Just as the key must have the correct shape to open the lock, the substrate molecule must exactly match the active center of the enzyme in order for a chemical reaction to occur. The concept of "key-lock" is still used by chemists. Moreover, it is developing and has found application in various fields of chemistry, including inorganic chemistry. Scientists at St. Petersburg State University and TPU applied the key-lock principle to complex inorganic molecules — polyoxometallates (POM). POMS are large anionic clusters consisting of oxygen atoms and transition metals such as molybdenum or tungsten. They have unique properties and are used in catalysis, materials science and even medicine. "During the study, scientists found that a certain type of POM — anion [β-mo₈o₂₆]⁴⁻ — exhibits selectivity in interaction with iodonium cations. This interaction can be described using the "key-lock" analogy. In this case, the iodonium cation acts as a "key", and the POM anion acts as a "lock". Interestingly, this selectivity is manifested only for one isomer (type) of POM," said Vadim Kukushkin, one of the key authors of the study, Honorary Professor of St. Petersburg State University, Academician of the Russian Academy of Sciences. According to him, this interaction is due to the formation of a special type of intermolecular interactions between a cation and anion — halogen bonds. Halogen bonds have been attracting more and more attention from researchers in recent years due to their unique properties and potential applications in the creation of new materials. The scientists note that this study demonstrates fundamental principles such as the key-lock concept.

The results obtained may find unexpected applications in modern chemistry. In the future, this discovery provides new opportunities for creating materials with specified properties based on specific interactions between ions. For example, such systems can be used to create new types of sensors capable of selectively recognizing certain ions in solution. Another important horizon that this work opens is the development of new catalysts. POMS are already used in catalysis, but the ability to precisely control their interaction with other molecules opens the way to the creation of even more effective and selective catalysts. This work became possible thanks to the collaboration of specialists from various fields of St. Petersburg State University and TSU within the framework of the Mendeleev scientific and educational cluster. St. Petersburg State University acts as a coordinator, promotes the development and implementation of projects that require combining the potentials and resources of organizations participating in the Mendeleev cluster. "Like the key-lock principle in the molecular world, cooperation between TPU and St. Petersburg State University demonstrates complementarity in science. TPU with technical experience acts as a "key", and St. Petersburg State University with a fundamental base acts as a "lock". Their interaction, as an ideal molecular correspondence, creates synergy, opening up new prospects in the study of chemical processes and the creation of innovative materials," said Vadim Kukushkin. Information provided by the press service of St. Petersburg State University

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The information is taken from the portal "Scientific Russia" (https://scientificrussia.ru /)