ИСТИНА

Coordination compounds of rare-earth compounds (REE) are extensively studied and employed for volatile and soluble precursors for inorganic REE-based materials, as emitting layers in OLEDs, as magnetic recording materials. Metal-Organic Frameworks (MOFs) attract a great deal of attention. Their development is limited by the absence of REE-based rigid Secondary Building Units because of structural flexibility of their compounds. During the last 5−7 years, the frameworks with polynuclear nodes Ln4(OH)4, Ln6(OH)8 or Ln6O8 of REE hydroxo/oxo carboxylates have been emerging in the literature. Up to now, only polynuclear hydroxonitrantes of REE containing an octahedral core O@Ln6(OH)8 with an oxide anion inside have been studied in detail. These compounds, however, easily disassemble theirself in solution because nitrate anions are weakly coordinated by REE ions and practically do not participate in the stabilization of the octahedral core. In order to organize the flexible REE compound into desired structures and to improve their stability we apply supramolecular chemistry approaches. Namely, hydrophobic interactions, H-bonds and specific packing effects were revealed and designed to promote self-assembly of polynuclear REE carboxylates. A series of isolated molecules (0D), coordination polymers (1D, 2D) and MOF (3D) structures based on {Ln2(Carb)2-4}, {Ln4(OH)2-4} and {Ln6(OH)8} species were synthesized and characterized. Stability of species was studied by DFT simulations with further electron density distribution analysis. Local and non-local structure transformations were studied by means of X-ray diffraction and Pair Distribution Function.