| In this paper, using Keggin, Wells-Dawson heteropolyoxometalates and reduced molybdenum phosphates clusters [P4Mo6] as basic building units, different kinds of N-containing ligands and transition metal ions, a series of new heteropolyoxometalate compounds have been synthesized by covalent bonds and hydrogen bonds under hydrothermal conditions, The influence of pH value, counter cations, solvents and charge density of coordinated atoms on the syntheses and structures of products have been investigated. The influences of different metal secondary building units on the structure of heteropolyoxometalates and possible synergetic effect among them have also been studied based on molecule design methods. The investigation of structures and properties is benefit for the effective syntheses of new POMs-based functional materials and developments of new theory and experiments.We choose bipy, bpp, im, pyz and pyd as organic ligands, different transition metal cations and heteropolyoxometalates as inorganic components, we have successfully synthesized new twenty organic-inorganic hybrid materials by adjust reactants under hydrothermal conditions. These compounds have been investigated by elemental analysis, IR, TG, XPS spectrum, electrochemical and X-ray diffractometer analyses.1. Using saturated Wells-Dawson POMs as building units, compounds （1-6） have been synthesized and characterized by the linkages of Cu+, Ni2+ ions （im = imizole, bipy = 4,4’-bipyridine, bipy = 2,2’-bipyridine, bpp=1,3-bis（4-pyridyl） propane）: [H2bpy]3（bipy）[ [P2W18O62]·1.5 H2O （1）[H2bpp]3（bpp）2[ [P2W18O62]·1.5 H2O （2）（Him）5[Cu（im）2][P2W18O62]·4H2O （3） [Cu3（Hbipy）3（bipy）1.5][P2W18O62]·H2O （4）（H2bpp）[Ni2（bpp）2（H2O）4(P2W18O62)]·H2O （5） {[Ni（bpp）（H2O）2]3[P2W18O62]}·24H2O （6）Compound 1 composes of [α-P2W18O62]6-, one free bipy, three protonated bipy and water molecule, supramolecular compound has been synthesized by hydrogen bonds andπ-πstacking interactions. Compound 2 consists of [α-P2W18O62]6- polyanion, three protonated bpp, two bpp and water molecule, supramolecular compound has been synthesized by hydrogen bonds andπ-πstacking interactions.Compound 3 composes of [α-P2W18O62]6-, [Cu（im）2]+, free im and crystal water, 1D chain structure has been generated by the weak interaction between [α-P2W18O62]6- and Cu（I）-im. Compound 4 contains a double-chain structure, and consists of a [α-P2W18O62]6-, a [Cu3（Hbpy）3（bipy）1.5]6+ unit and crystal water in the asymmetric unit. Two adjacent [α-P2W18O62]6- units are linked into a 1D chain by“stick 2”, and two 1D chains are extended into a unique 1D double-chain structure by“stick 1”. Compound 4 represents the first Wells-Dawson POM double-chain structure.Compound 5 composes of a [α-P2W18O62]6- ion, two Ni2+ ion, two bpp ligands, four coordinated water molecule, a free H2bpp2+ ions and crystal water. It has a anatase topological structure with [α-P2W18O62]6- as six-connected nodes and Ni2+ as three-connected nodes to generate a （3,6）-connected 3D net. Compound 6 crystallizes in Pm-3n, 3D cubic, and is a porous framework based on Dawson POMs, octahedral {NiN2O4} units and flexible bpp ligands. The topological analysis of it shows a unique Perovskite polyporous cubic framework with two kinds of cavities. It represents the first Dawson POMs cubic framework by covalent bonds.2. Six POMs compounds have been hydrohthermal synthesized and characterized based on organic ligands bipy, bpp, Dafo and Keggin POMs unit （dafo = 4, 5-diazafluoren-9-one, pyd = pyridine）: H3（H10C4N2）3[PMoVI12O40] （7）H3（bipy）3[PMoVI12O40] 3 H2O （8）H5（bipy）5[BW12O40] 3H2O （9）H3（bpp）2[PW12O40] 2H2O （10）H4（bpp）2[SiW12O40] （11） H4[L1]2[PWVI11WVO40]·6H2O （12）Compounds 7-12 all 3D supramolecular frameworks based on Keggin POMs units and organic ligands via hydrogen bonds andπ-πstacking interactions. Compound 12 generates a new ligand L due to the in-situ reaction of ligand Dafo.Six POMs compounds have been hydrohthermal synthesized and characterized based on organic ligands bipy, bpp, im, Dafo, pyd and Keggin POMs units （dafo = 4, 5- diazafluoren -9 -one, pyd = pyridine）: [Ag（dafo）]2{(PW12O40)[Ag（4,4’-bipy）]} （13）Ag（bipy）2[Ag（bipy）2]2}{[Ag（bipy）]2(PW12O40)]} （14）{[PMoVI12O40][Ag（4,4’-bipy）3]（4,4’-bipy）}H2O （15）Na2[{Ag10（C6H4NO2）8（H2O）6}(SiW12O40)] （16）{Ag（pyz）)2[Ag（pyd）2]8[(PW12O40)2]}n （17） （2,2’-bipy）[[Mn（2,2’-bipy）2（H2O）]2[SiW12O40] H2O （18）Compound 13 consists of two basic units [Ag（4,4’-bipy）]+ and {[Ag（dafo）2]2(PW12O40)}-. The fragmets {[Ag（dafo）2]2(PW12O40)}- link together to generate the 4×4 porous with 16.62×16.69 ’2 cavities, On the other hand, it contains other fragment, 1D chain was constructed from Ag（1） and two 4, 4’-bipy, [Ag（4, 4’-bipy）]nn+ penetrate the cavities to assemble 1D + 2D = 3D supramolecular framework. Compound 14 contains three basic units, {[Ag（bipy）]2(PW12O40)]} fragments, Ag（bipy）2 and [Ag（bipy）2]2} fragments, there are five crystallographic independent Ag+ ions, one Keggin aions [PW12O40]3-. The Keggin anions could link together by covalent bonds with Ag （3） and Ag （4）. Ag （1）, Ag （2） and Ag （5） connect with two （bipy） to assemble free transition metal complex fragments. Supramolecular structures could be generated by hydrogen bonds. The basic unit of compound 15 contains two crystallographic independent Ag+ ions, one Keggin anion, one free 4,4’-bipy and one free water molecule. Ag（1） and Ag（2） connect with [PMo12O40]3- anion via weak interaction Ag-O. So adjacent POM anions connects with [Ag（4, 4’-bipy）2]n fragments to build 2D layers, then 2D layer extended to 3D supramolecular structure via weak interactions.Compound 16 consists of aα-Keggin [SiW12O40]4- basic motif, four crystallographic independent Ag+. [SiW12O40]4- link six Ag atoms to build （3,6）-connected topologies. Interestingly, IN comes from the in-situ reaction of bpp in this compound. Compound 17 contains [Ag（pyd）2]8[(PW12O40)2]}n fragments and Ag（pyz）2 fragments, three crystallographic independent Ag （I） ions. [PW12O40]3- anions connect with eight Ag （I） via covalent bonds and weak interactions. Firstly, Ag1 links pyridine ligands to construct 1D chain structures. Ag（3） ions link chain and POMs units to build 2D layers, and 3D frameworks. Compound 18 is a bis-supported structure which contains oneα-Keggin [SiW12O40] 4- units, one crystallographic independent Mn2+ ions, one free bipy and one free water molecule. The supported structure builds 1D supramolecular chain along a axis, then the 1D chain extended to 3D supramolecular structure via short interaction andπ-πstacking interactions between oxygen atoms and 2,2’-bipy.3. Two novel transition metal complex molybdenum phosphates have been prepared and characterized by the linkage of reduced [P4Mo6] units and Cd2+ and Mn2+ions: （Hbipy）2[Cd（H2O）]3[Cd（H2PO4）2（HPO4）4（PO4）)2（OH）6（MoO2）12]·5H2O （19）（H2bipy）3[Mn（H2O）2]2[Mn（HPO4）6（PO4）2（OH）6（MoO2）12]·10H2OCompound 19 represents the first example that 1D inorganic chain structure was built from three-core transition metal clusters {Cd3} as bridging units and dimeric Cd[P4Mo6]2 via covalent bonds, then 3D supramolecular frameworks could be assembled by the hydrogen bonds among 1D chains, protonated 4,4’-bipy and solvent water molecule. In compound 20, 2D inorganic layers could be linked by dimeric Mn[P4Mo6]2 and Mn2+ ions, two adjacent 2D inorganic layers interact with protonated 4,4’-bipy by hydrogen bond to assemble Hydrotalcite structure 3D supramolecular compounds. |
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