Synthesis And Property Study Of Polyoxometalate Compounds Modified By Cu-Ligand Group

Polyoxometalates （POMs） is a kind of nano-sized inorganic anionic cluster, which hasextensive applications in catalysis, medicine, material. Nowadays, they have not only beenlimited to the research in inorganic metal-oxygen clusters, but also the surface modification ofstructure and researchs. This paper mainly focuses on simple molybdates or tungstates as theraw materials and introducing Cu-ligand groups to construct new POM-based compounds.Here nine compounds have been synthesized and characterized by elemental analysis, IR,thermogravimetric analysis and XRD powder diffraction. The electrochemical behaviors ofcompounds have been also studied.（1） Four capped-Keggin-type structures have been synthesized under hydrothermalconditions:[Cu（mbpy）₂]₂[PMo₁₂O₄₀Sb₂]·4H₂O （1）[Cu（mbpy）₂][PMo₁₂O₄₀Sb₂]·4H₂O （2）{Cu（mbpy）[Cu（mbpy）₂]₂}[VMo₈V₄O₄₀Sb₂]·2H₂O （3）[Cu（mbpy）]₄[PMo₁₂O₄₀]·4H₂O （4）Compounds1-3consist of bi-antimony capped-Keggin clusters, while compound4presents a bi-copper capped-Keggin cluster. The cationic moieties in1-4are Cu-mbpy （mbpy=4,4’-Dimethyl-2,2’-dipyridyl or5,5’-Dimethyl-2,2’-dipyridyl） fragments, in which Cucenters with different valent states show different coordination environments.（2） Two one-dimensional polyoxometalate compounds have been obtained throughhydrothermally synthesis methods. Compound5is built on Keggin-type [VW12O40]4-anion;and compound6is new {Mo₆} isomolybdate:[Cu（mbpy）]₆[（HPO₄）₄(VW₁₂O₄₀)]·4H₂O （5）[Cu（mbpy）（OH₂）]₂[Mo₆O₂₀]（6）Compound5is a1D cationic chain structure built upon eight-element rings of{Cu-O-P-O}2units. The1D structure in compound6consists of isopolyanion molybdenumoxygen grafted by Cu-mbpy groups.（3） A large wheel-cluster structure and a case of phosphorus manganese cluster complexes have been synthesized:Na₈Ni₃[(Mo₁₆O₃₂)Ni₁₆（H₂PO₄）₄（HPO₄）₁₀（PO₄）₁₂（OH）2（H₂O）8]·40H₂O （7）[Mn（H₂O）]₄[Mn（HPO₄）₂（PO₄）₂]（8）Compound7represent a wheel-like Mo-O-Ni cluster. There existed a large size cavity inevery wheel cluster. It could also be viewed as multidimensional porous structure.（4） By using molybdenum oxide as the raw material, and introducing flexible organicunit [bpp=1,3-Di（4-pyridyl）propane], a Keggin-based supramolecular compound isconstructed:[H₂bpp]₂[PMo₁₂O₄₀]·2H₂O （9）...