Guralskiy I. Fe(II) spin-crossover complexes and materials on their basis as multifunctional switches

This thesis describes the preparation and investigation of spin-crossover compounds, characterization of their structures, magnetic and optical properties, preparation of composites and nanomaterials on their basis, study of spin-crossover effects on electrical and optical properties of complexes, development of mechanical elements working via the phenomenon of spin crossover. A series of new spin-crossover complexes was obtained. They belong to three different classes of coordination compounds: cyanoheterometallic frameworks, complexes with 1,2,4-triazoles and complexes with polycyclic chelating ligands. The effect of spin crossover in Fe(II) complexes and materials on their basis was studied using magnetometry, Moessbauer spectroscopy, calorimetry and optical microscopy. It was shown that compounds of these classes can display spin crossover in a wide temperature range and with different characteristics of the transition. It was shown that chiral materials with spin transition have a spin dependent response of circular dichroism, and also can act as active compounds for enantioselective detection. Spin crossover can cause a drastic change of electric properties of a coordination compound and its ability to absorb microwave radiation. Mechanical changes upon spin transition allowed to develop effective micromechanical constructions that use this effect of molecular switching.