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Multifunctional spin-crossover materials

Work number - M 28 FILED

Presented Taras Shevchenko National University of Kyiv

Illia Guralskyi, Ph.D. in Chemistry, senior research associate.

Purpose and objectives of the research: the purpose of this work was to develop new coordination compounds and materials based on them with a wide range of spin transition characteristics, as well as to study the ability of these materials to function as chirooptical and microwave switches. The tasks of this work were the following: development of ligand systems and obtaining of new spin-crossover compounds; study of the phenomenon of spin transition in the synthesized complexes, establishment of correlations between the structure of the complex and the morphology of the material with the characteristics of the spin transition; study of the influence of spin transition on the chirooptical properties of complexes; study of enantioselective guest effects on spin transition; study of the interaction of complexes in different spin states with microwave radiation.

Scientific novelty of the obtained results: a series of novel spin transition complexes were obtained based on pyrazine, substituted pyrazines, pyridazine and various chelate ligands with unique spin transition characteristics (temperature, sharpness, completeness, hysteresis). Chiral nanoparticles and gels with spin transition were obtained, they were shown to change their chirooptic properties upon spin transition. For the first time, the enantioselective effect of alcohol sorption on a chiral complex with a spin transition is shown. Mechanical actuators that use the effect of spin transition to generate motion were developed. It was shown that the absorption of electromagnetic radiation of the microwave range by a complex effectively changes upon spin transition.

The practical significance of the obtained results: the development of complexes with spin transition is one of the promising ways of creating new switchable materials that have variable transition characteristics. The obtained complexes of three classes have spin transitions at different temperatures (with and without hysteresis); in particular, a complex with hysteresis of spin transition at room temperature was obtained. This makes new compounds promising for thermometry within a wide range of temperatures, for use as protective elements, thermochromic pigments etc. Variable chiro-optical properties can allow the integration of the obtained materials into optical elements, and the enantioselective sensitivity to chiral analytes makes it possible to use the complexes as active compounds of enantioselective sensors. The effect of significant expansion of complexes during spin transition allows their use in mechanical structures with thermal, optical and electrothermal mechanisms of action. The change in microwave absorption during the spin transition is promising in the context of radio frequency wave control.

Number of publications: the work submitted for the competition includes 18 papers published in international refereed journals and 20 abstracts. In total, the author published 46 articles on the subject of the research, all of which are indexed by Scopus database, 44 abstracts and 1 patent of Ukraine, h-index of the author is 19. Number of citations of the articles, included to this work/h-index of the work in databases: Web of Science – 125/7; Scopus – 125/7; Google Scholar – 140/7.