Syntheses, Structures And Properties Of 12-Polyoxotungstates Functionalize By Transition Metal Complexes

Polyoxometalates (POMs), have been employed as building blocks to construct inorganic–organic hybrid compounds owing to not only their intriguing structural and topological novelty but also potential applications in such as photochemistry, catalysis, electrical conductivity, material science and magnetism. An acknowledged fact is that the synthesis of such hybrids depends on the proper selection of POMs as inorganic building blocks and transition-metal complexes (TMCs) as structure-directing and functional components. In this paper, four new compounds based on 12-polyoxotungstates have been synthesized via water solution synthesis methods together with hydrothermal technique. These compounds are structurally characterized by elemental analyses, IR, UV, TG and single crystal X-ray diffractions.1. One novel paradodecatungstate derivative has been synthesized by water solution synthesis method and structurally characterized: H4{[Cu3(2-Hpzc)2(H2O)4](H2W12O42)}·13H2O (2-Hpzc = 2-pyrazinecarboxylic acid) (1). In the structure of compound 1, each paradodecatungstate anion acts as a quadridentate ligand coordinating to four Cu2+ cations through its terminal oxygen atoms to form a two-dimensional (2D) layer. The infinite [Cu(2-Hpzc)]2+ chains connect adjacent layers forming a three-dimensional (3D) architecture. To our knowledge, compound 1 represents the first high-dimensional hybrid based on paradodecatungstate and Cu-2-Hpzc complexes. A fascinating structural feature is that the three-dimensional framework contains two kinds of channels with sizes of ca. 5.737×4.628 ? and ca. 9.104×8.640 ? along the b and c directions, respectively, water molecules fill in the channels. The magnetic behavior of 1 exhibits antiferromagnetic interaction.2. We have get three compounds by utilizingα-SiW12O404- polyanion as a precursor and choosing hydrothermal technique. [Cu(imi)]4[SiW12O40] (imi = imidazole) (2) (bpe)[Cu(bpe)]3[HSiW12O40]·4H2O (bpe = 1, 2-bis(4-pyridyl)ethane) (3) (bpe)[Mn(bpe)]2[SiW12O40]·2H2O (4)3. Compound 2 is a disupported compound, Keggin polyanion regarded as a bi-dentate liagand simultaneously provides two terminal oxygen atom to coordinate to two {Cu(imi)2} fragments. Compounds 3 and 4 were synthesized under similar conditions except for selection different transition metal cations, which can form 1D"ladder"style chain through the linkage of Cu/Mn ions. However, there exist some differences between the two compounds. In compound 3, the isolated infinite [Cu(bpe)]n+n and [Cu2(bpe)2SiW12O40]2n?n chain connect to 2D supramolecular structure through the weak Cu-O interaction. In compound 4, every two [Mn2(bpe)2SiW12O40]∞infinite chain connect to 2D supramolecular structure through the weak Mn-O interaction.