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Synthesis, Structures And Spectroscopy Properties Of Polyoxovanadium Borate Compounds

Posted on:2012-12-29Degree:MasterType:Thesis
Country:ChinaCandidate:G M LiFull Text:PDF
GTID:2181330452962010Subject:Physical chemistry
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With the development of polyoxometalate chemistry, the design and synthesis oforganic-inorganic hybrid compounds containing polyoxometalate units withremarkable structural, physical and chemical properties have drawn an increasingchemist’s interest, especially for their potential applications in the fields ofluminescence, magnetism, electronic, gas adsorption and catalytic activity properties.Organic-inorganic Polyoxovanadium Borate compounds are as an important branch ofthe polyoxometalate compounds, has its potential application prospect.Based on summary of literature search systematically, we carried out thesynthesis, structures and spectroscopy properties of polyoxovanadium borates.1. In this work, we successfully got ten polyoxovanadium borate compounds byhydrothermal synthesis:Na[V12B16O50(OH)7(en)]2(en)8(H3O)13(H2O)71Li4[V12B16O50(OH)8](H3O)4(H2O)212Na3[V12B16O50(OH)8](en)2(H3O)5(H2O)23Na8[V12B16O50(OH)8](en)2(H2O)10.54Mn2[V12B16O50(OH)8](en)2(H3O)4(H2O)75[Na(H2O)]2[Na(H2O)2]2[Cu(en)2][V12B18O54(OH)6](H3O)2(H2O)186Na16[Cu(en)2]4[V12B18O54(OH)6]2(BO3)2(H2O)30(H3O)27K12[V12B18O54(OH)6](H2O)15(OH)48K24[V12B18O54(OH)6]2(H2O)24(OH)89 [V12B18O54(OH)6]2(SO4)4(en)10(H2en)4(H3O)1610These compounds1-10with abundant structural features were determined bysingle-crystal X-ray diffraction. Compound1consists of a interestingorganic-inorganic hybrid [V12B16(en)] cluster formed by B-N, the clusters connectwith each other by Na+and hydrogen bond to form a three-dimensional(3D) architecture.Compounds2-5contain a [V12B16] cluster. Compound2shows a3D architecture withclusters connected by Li+, compounds3-4show a3D architecture with clustersconnected by Na+, compound5exhibits a3D architecture with clusters connected byMn2+and hydrogen bond. In addition, compounds6-10contain a [V12B18] cluster,compounds6-7show a3D architecture with clusters connected by Na+and[Cu(en)2]2+, compounds8-9show a3D architecture with clusters connected by K+,compound10exhibits a3D architecture with clusters connected by hydrogen bond. Inorder to further research on structure of compounds1-10, the TOP4.0is introducedfirstly to polyoxovanadium borate. The pore ratio is high, except componds3,4,8,9.2. In order to further research on the frameworks of compounds1-10, theTOP4.0is firstly introduced into polyoxovanadium borate field. The topology of1isNb2O5net, in addition, The topology of2、3、6、10is pcu alpha-Po primitive cubicnet, The topology of8is alb net. To our knowledge, The topology of4、7、9is a newtopological structure.3. Based on the structure of compounds1-10from X-ray single-crystal diffraction, the properties have been characterized with FTIR,2D IR correlationspectroscopy (2D-IR COS), ultraviolet-visible absorption spectrum (UV-Vis DRIS)and thermogravimetric analysis (TGA). FTIR spectrum show a characteristic peak ofpolyoxovanadium borates. From2D-IR COS analysis with magnetic perturbation of1,2,4,6,9, the evidence for understanding the groups coordinated with magneticparticles can be founded. In addition, From2D-IR COS analysis with thermalperturbation of1,2,5-7,10, V=Otasymmetric stretching vibrations are not sensitivewith thermal perturbation, however, V=Otsymmetric stretching vibrations are sensitivewith thermal perturbation, therefore, it is founding that V=Otsymmetric stretchingvibrations are more sensitive with thermal perturbation than V=Otasymmetricstretching vibrations. In UV-Vis DRIS spectra, the LMCT bands of O→M were foundat about206nm and the LMCT bands of O→M split into two peaks caused bycomplex coordination environmental. It is found that with the rise of temperature,compounds have two or three ranges of weight losing, corresponding to the loss ofwaters and ethylenediamine (en) molecules from TGA diagram. Thepolyoxovanadium borate cluster exsists stably below400°C. Good thermal stabilityand high pore ratio make polyoxovanadium borates potentially used in materials.4. In order to confirm the accuracy of the2D-IR COS analysis with thermalperturbation and thermal gravimetric analysis, firstly introduced thermal infraredspectrum to polyoxovanadium borate field. its can clearly observed changes of peakon IR spectrum under the tempreture with more than120°C. In compound6,Whenthe temperature is rised to550°C, the peaks of718,953,1041and1408cm1on IRspectrum are steadily existed, it means the V12B18cluster is also existed. The resultsof thermal infrared spectrum are consistent with2D-IR COS analysis with thermalperturbation and thermal gravimetric analysis, there are shows thermal stabilityproperties of compounds from three different angles.5. In this work, the V12B18cluster anion of compound10was carried out by thequantum chemical calculation. It is mainly discussed the net charge and reactionactivity center. μ2-O and Otare more easier to be as the receptors for cations orpositive charged protons offense. μ3-O may be as the catalysis activity center.
Keywords/Search Tags:organic-inorganic hybrid, Polyoxovanadium Boratecompounds, crystal structure, spectroscopy analysis, quantumchemistry calculation
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