Synthesis, Structures And Properties Of Supramolecular Assemblies Based On Classical Polyoxometalates

In this thesis, we study the construction of a series of organic-inorganic supramolecular compounds based on the classical Keggin and Wells-Dawson type polyoxometalate building blocks and different rigid ligands, flexible ligands and lanthanide cationic cluster, investigate the synthetic conditions and rules for these compounds and observe the relationship between the structures and properties for these new compounds.Five new organic-inorganic supramolecular compounds based on polyoxometalate building blocks have been synthesized under hydrothermal conditions, and structurally characterized by elemental analysis, IR, and single crystal X-ray diffractions. The electrochemical properties of these compounds have been studied.1. Two supramolecular compounds 1 and 2 have been synthesized based on Keggin type polyoxometalate building blocks, through using rigid organic ligand Me2bpy and flexible ligand bbi: [H₃(Me₂bpy)₄][PW₁₂O₄₀]·3H₂O (1) [H₃(bbi)_2.5][PMo₁₂O₄₀]·H₂O (2)Compounds 1 and 2 were synthesized under identical conditions, except for choosing organic ligands with different nature, which induce different supramolecular packing modes. In compound 1, rigid ligand Me2bpy can afford abundantÏ€?Ï€stacking interactions, which induce forming line-style supramolecular chains. In compound 2, the flexible bbi ligand can rotate and bend flexibly and form wave-like chains throughÏ€?Ï€stacking interactions and hydrogen bondings. The polyanions disperse in the void between adjacent chains.2. Three new isostructural compounds 3?5 based on Wells-Dawson building block have been synthesized and characterized through using dimeric lanthanide cluster: [Tb₂(C₆H5NO₂)₄][P₂W₁₈O₆₂]·14H₂O (3) [Sm₂(C₆H5NO₂)₄][P₂W₁₈O₆₂]·15H₂O (4) [Yb₂(C₆H₅NO₂)₄][P₂W₁₈O₆₂]·16H₂O (5)In compound 3, the two Tb atoms are bridged by three bidentate C₆H₅NO₂ ligands to construct a dimeric cluster [Tb₂(C₆H₅NO₂)₄]³⁺. Viewing along the c axis, the polyanions and countercations form 2D wave-like layers. 1D channels are formed between adjacent layers, which are occupied by water molecules.