Study On Organic - Inorganic Hybrid Based On Polymolybdic Acid Cluster Compounds

As a part of polyoxometalates (POMs), isopolymolybdates have been employed as inorganic building blocks to build functional molecular materials with the special structure and properties, especially for constructing organic-inorganic hybrid materials. In this paper, several novel organic-inorganic hybrids based on isopolymolybdates have been prepared by reacting MoO3 or ammonium molybdate as inorganic reactants and organic N-donor ligands (1,4-bis(imidazolyl)benzene, 1,4-bis((1H-imidazol-1-yl)methyl)benzene and 4H-4-amino-1,2,4-triazole et al.) in controlling conditions, such as pH, temperature and the amount of reactants. These organic-inorganic hybrids were characterized by elemental analysis, IR, UV-vis spectra and TG-DSC, part of them characterized by magnetism measurements and cyclic voltammetry. Their structures were determined by X-ray single crystal diffraction analysis.1. Three novel organic-inorganic hybrids based on octamolybdate have been synthesized: (NH4)6n[Mn(H2O)2Mo8O28]n(H2O)2n (1) [Cu2(bib)3(β-Mo8O26)]·2H2O (2) [Cu2H4(bix)6(α-Mo8O26)(β-Mo8O26)]·2H2O (3)In compound 1, the unique [Mo8O28]8- anions act as tetradentate ligands and are alternately linked by Mn(H2O)22+ ions into a one-dimensional chain structure. As a derivative of [Mo8O26], [Mo8O28] subunit has Ci symmetry and is composed of eight {MoO6} octahedra. It is interesting that 1 represents the first example of pure inorganic-inorganic hybrid based on octamolybdate and transition metal ions. In compound 2, (β-Mo8O26)4- anions connect with trapezoidal polymer chain {Cu2(bib)3}n to form a 2D framework. The polymer chain composed of transition metals and bib has never been observed before. In compound 3, two kinds of octamolybdate anions, [α-Mo8O26]4- and [β-Mo8O26]4-, are alternately linked with one-dimensional polymer chain [CuH2(bix)3]n to form a 2D structure.2. A new organic-inorganic hybrid based on decamolybdate has been synthesized under hydrothermal condition: (NH4)2n[Cu3(atrz)6Mo10O34]n(4)The decamolybdate subunit{Mo10O34} in 4 represents a new type of decamolybdate unit, which has Ci symmetry and the structure of the decamolybdate subunit is different from the reported{Mo10O34} polyanion. The capped{MoO6} octahedra of decamolybdates and the external copper ions of the linear trinuclear cation [Cu3(atrz)6]6+ further connect alternately to form a 1D chain. Magnetic measurement reveals the antiferromagnetic interactions among the Cu3 cluster.3. A new organic-inorganic hybrid based on heptamolybdate has been synthesized by conventional solution method: Na2(H2O)7Cu(enMe)2Mo7O24·2H2O (5)In compound 5, a bridging oxygen atom from [Mo7O24]6- connects with cupric ions from [Cu(enMe)2]2+ to form the organic-inorganic hybrid [Cu(enMe)2Mo7O24]2+, which further interacts with other components to construct the supermolecular structure by salt bonds and weak interactions.4. A new organic-inorganic hybrid based on molybdenum oxide has been synthesized under hydrothermal condition: [(MoO3)2(atrz)2]n (6)In compound 6, six coordination atoms of Mo are from four O atoms and two N atoms of two ligands atrz, respectively. The neighbouring Mo atoms are connected through bridge O atoms and bidentate atrz ligands to form a one-dimensional zig-zag infinite chain.