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Structural Chemistry Of Novel Vanadium Tellurite

Posted on:2004-01-23Degree:MasterType:Thesis
Country:ChinaCandidate:X H HuangFull Text:PDF
GTID:2121360095455175Subject:Physical chemistry
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The structures and properties of the compounds are profundity affected by the unusual stereochemical effects of the so-call lone-pair elements in heavy p-block elements. With the effect of lone-pair, the coordination atoms of heavy p-block elements located the same side, which can lead to reducing the structure dimension. This characteristic can be used as scissors to devise the structure. The research on composite oxides of heavy p-block elements and transition metal elements, especially the early transition metal elements, is an appealing area for their great potential practical applications in many fields, such as, catalysis, fast ion conductor, ferroelectric materials, piezoelectric materials, optics materials and so on. The tellurium atom and vanadium atom possess enrich coordination geometries and flexibility conjunct modes; and the organic groups can control and modify the structure of inorganic framework, for its rigidity in conjunct mode, flexibility in stereochemical and strong capability of coordination. The research on vanadium tellurites is limited so far, and the study on synthesis and characterization of vanadium tellurites is still unexpanded. So it is significant to synthesize novel vanadium tellurites, study the rule of assemble, structure and the relation between structure and properties.This dissertation focus on the synthesis, structure and characterization of vanadium tellurites, especially organic-vanadium-tellurites; at the same time, we intended to find the relationship between properties and structures. In this work, we inducted some organic groups into vanadium tellurites successfully. So far we had made achievements on such aspects:(1) Synthesize ten novel vanadium tellurites and one novel linear tri-nuclear oxo-vanadium cluster, determined the structure of these compounds by X-ray single crystal diffraction technology. They were NH4[V2TeO7] (VTO1), (NH3CH2CH2NH3)2[V2Te2O11] (VTO2), (NH3CH2CH2NH3)[V2Te2O10] (VTO3), [NH2(CH2CH2)2NH2][V2Te2O10] (VTO4), (NH3CH2CH2NH3)[VTe3O9] (VTO5),K3V5Te4O20·4H2O (VTO6), (NH3CH2CH2CH2NH3)[V2TeO8] (VTO7), [NH3CH2CH(CH3)NH3][V2Te2O10](VTO8), [(NH3CH2CH3)2NH](H2O·OH)[V2Te2O10] (VTO9), [NH2(CH2CH2)2NCH2CH2NH3][V2Te2O10](VTO10) and [VO2(phen)(OSO3)(H2O)]2[VO(phen)(H2O)]·5.5H2O (V-3). In addition, NaVTeO5 was obtained under the hydrothermal condition, which was formerly synthesized by high temperature solid state reaction in report. In all the compounds, the Te-O polyhedrons and V-O polyhedrons build up the anion frameworks through corner-sharing, edge-sharing or face-sharing. Among these compounds, the vanadium atom possess +4 valence in VTO5, +4 and +5 mixed valence in VTO1,VTO6 and V-3, and +5 valence in other compounds. VTO2,VTO10 and NaVTeO5 are of 1D chain frameworks, VTO1,VTO3,VTO4,VTO7,VTO8 and VTO9 are of 2D layer frameworks, and VTO6 is with extended 3D tunnel structure. There are extensive hydrogen bonds in these ten compounds.(2) The effects of reaction conditions on the outcome phase are considered and studied systematically. We have conquered the difficulties that oxidation reaction occurs easily at high temperature and contents cannot diffuse efficiently, and find a convenience method for synthesizing HnL-VTO.(3) The characteristic of Te-O polyhedron structure and the mode of Te-O bond are classified and reviewed based on summary of literature about tellurite. The relationship between the structure of framework and the linkage of Te-O polyhedron is discussed.(4) The IR spectrums of the 11 novel compounds have been characterized.(5) DSR and fluorescent spectrum are employed to characterize the 11 novel compounds and ESR is employed to characterize VTO5, VTO6 and V-3.The DSR spectrums show the compounds with unpaired electron (with V+4 atom) possess broad absorbed peaks at VIS wave range, and the compounds with only V+5 atom show a obvious absorption edge. Strong emission peaks are observed for all of the compounds under exciting of ultraviolet light. The ESR spectrums of VTO5,VTO6 and V-3 indicate that they p...
Keywords/Search Tags:vanadium tellurite, organic group, hydrothermal synthesis, crystal structure, spectrum analysis, electronic structure calculation
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