The Synthesis, Crystal Structure And Properties Of Organic-Inorganic Hybrid Compounds Containing POMs

The synthesis and preparation of organic- inorganic hybrid compounds is an important part of molecule designing in modern chemistry. The self-assembly is adopted to achieve purposeful synthesis through selecting the transition metal cations as templating and organic ligands with multi-coordinate atoms, polyoxometalates (POMs) as building blocks. In this paper, two novel Organic- Inorganic Hybrid Compounds Containing POMs were achieved by selecting POMs with unique structure and properties and organic ligands with bipyridyl groups as building blocks and transition mental cation as templating through hydrothermal reaction.A hydrothermal reaction of WO3, CoCl2 and 4,4'-bipyridine yields a novel organic-inorganic hybrid compound, Co2(bpy)6(W6O19)2, at 170°C. X-ray single crystal structure determination reveals a two-dimensional covalent structure which adopts (W6O19)2- as inorganic building blocks, bpy as organic building blocks, and Co(II) as templating species. Its single crystal structure belong to monoclinic crystal system, space group C2/c, with cell parameters a = 19.971(4) ?, b = 11.523(2) ?, c = 16138(3) ?, ( = 96.49(3)°, V = 3690.0 ?3 and Z = 2. The structure of this compound is novel because (W6O19)2- is connected into extended structure which is unparalleled. A hydrothermal reaction of NH4VO3, CoCl2 and 1,3-bis(4-pyridyl)propane(bpp), yields a novel organic-inorganic hybrid compound, [Co(bpp)2V2O6] ·2H2O, at 120°C. X-ray single crystal structure determination reveals a three-dimensional covalent structure which adopts (V4O12)2- as inorganic building blocks, bpp as organic building blocks, and metal Co(II) as templating species. Its single crystal structure belongs to Tetragonal crystal system, space group I4, with cell parameters a = 21.5674(7) ?, α?= 90°,b = 21.5696(7)?, ( = 90°, c = 12.8126(4) ?, γ= 90°, V = 5960.4(3) ?3 and Z = 8. In this compound, the 2-D 2∞{Co (bpp)2}n2n+ cation chains are interpenetrated into channels which are occupied by (V4O12)4- through V-O-Co bonds. From UV-Vis-NIR reflectance spectra, it's found that these two compounds have optical energy gap of 2.2eV and 2.1eV, respectively, and both belong to semiconductor.The influence of the reaction conditions on the products such as mole ratio of reactants, the pH value of the reaction solution and the reaction temperature were discussed through many practical experiments; the optimum conditions of these reactions are determinated.