ИСТИНА

The design and study of molecular compounds exhibiting various structural topologies capable of exhibiting interesting physical and chemical properties, such as catalytic, magnetic, and optical ones, constitute one of the major fields in strong development. In particular, the metalasil- or germsesquioxanes containing transition metal ions or lanthanides represent a fascinating family of molecular compounds due to the diversity of their structural organization and their physical properties. The aim of this work was therefore the synthesis of several families of sil- and germsesquioxanes containing transition metal ions or lanthanides and the study of their catalytic, magnetic, and optical (luminescence) properties. A self-assembly reaction based approach has been improved for the synthesis of Cu(II)-containing silsesquioxanes. Thus, 51 metalsilsesquioxanes containing from 2 to 11 Cu (II) ions have been synthesized, characterized, and investigated. The impact of various parameters, such as the presence of organic substituents on the silicon atom, the nature of the solvent, the use of additional ligands, the use of bridging ligands on the structural organization has been demonstrated. The approach used for the synthesis of metallasilsesquioxanes has also been transposed to germsesquioxanes containing Cu (II) ions with the synthesis of five new polynuclear compounds. The catalytic and magnetic properties of Cu (II) sil- and germsesquioxanes have been investigated. The synthesis of sil- and germsesquioxanes of Ni (II) was carried out and two complexes Ni4Na2-phenylgermsesquioxane and Ni4-pyridine-carbonate were obtained and studied. The study of the magnetic properties of these compounds shows the presence of slow relaxation of the magnetization due to the spin glass behavior. Finally, four new tetranuclear metallasilsesquioxanes containing Eu3+ and Tb3+ were synthesized, characterized and their magnetic and optical properties (luminescence) were studied. These compounds exhibit an unusual prism-shaped cage topology. The study of their magnetic property revealed that the Tb3+ -based compound exhibits a spin-flip transition induced by the magnetic field from the canted state to the paramagnetic regime. Remarkably, these compounds show a characteristic luminescence of Eu3+ or Tb3+ at low temperature (77 K) or at room temperature in the solid-state and can be considered as the first luminescent lanthanide-silsesquioxanes. Key words: metallasilsesquioxanes, metallagermsesquioxanes, coordination compounds, catalysis, magnetic properties, luminescence