Synthesis, Structure Chemistry Of Polyoxometalate And Dye-polyoxometalate Supermolecules

The time of structure scissor and self-assembly in synthesis of polyoxometalates is coming, and now a quantity of polyoxometalates with novel structure were synthesized with the organic templated directing. Polyoxometalates have received a lot of interest in research because of their potential applications in the areas such as catalysis, medicine and functional materials.Based on the systematic investigation on the literature in polyoxometalates research, we carried out the study about hydrothermal synthesis of polyoxometalates and intended to find the relationship between properties and structures. At the same time, we synthesized the dye-polyoxometalate supermolecules and studied the spectrum characterization about them systematically, discussed the reaction activity center and inferred the reaction mechanism. So far we had made achievements in two aspects: synthesis and characterization study on polyoxometalates and the dye-polyoxometalate supermolecules. 1. Devising and synthesizing nine novel polyoxometalates and employing X-ray single crystal diffractometer technology to determine their structures:[{Ni(phen)₂}₂V₄O₁2]H₂O (â… )[{Fe(phen)₃}₂V₄O₁2] >19.3H₂O (â…¡)[N(CH₂CH₂)₃NH]Na(H₂O)₆{K₄(H₂O)₄[V₁0O₂8]}(H₂O)₄ (â…¢)[(CH₃)₄N]₆[V₁5O₃6Cl] (â…£) (NH₄)₁.33[M_o6O₁8] (â…¤)Na[Fe₂(O₂H₃)M_o2O₈] (â…¥)(NH₄)[Fe(M_oO₄)₂] (â…¦)Mn₅(PO₃(OH))₂(PO₄)₂(H₂O)₄ (â…§)[(CH₃)₂NH₂]₃[PW₁2O₄0] (â…¨)Among these compounds, compound â…  and â…¡ all possess [V₄O₁2] group. In the compound â… , [V₄O₁2] offers the terminal oxygen atom to coordinate with nickel atom in the Ni(phen)₂, but in the compound â…¡, Fe(phen)₃ exists as a counter cation. In the compound â…¢ [V₁0O₂8] groups are connected by K⁺, but [V₁5O₃6Cl] group incompound â…£ is an isolated clusters. Compound â…¤ is a hexagonal ammonium molybdenum bronze with dissaturation value, and NH4^{＋} statistically reside in the tunnels with 3/4 c axis distance between ammoniums. Compound â…¥,â…¦ and â…§ all possess infinite three-dimensional framework structure, but compound â…¨ is a polyoxotungstate supermolecule with Keggin-type.Employing DRS, IR, fluorescent spectra and TGA to characterize some compounds. We found the characteristic peaks of M-O, O-M-O are related to the structures; In UV-Vis DRS spectra, the LMCT bands of O→M are found in the range 200nm to 400nm. The fluorescent emission peak is related to the inorganic framework. TGA diagram shows the process of compounds losing the crystal waters or organic molecules respectively. At last, quantum chemistry calculations were carried out on two kinds of polyoxometalates, discussing the properties of bonds and the electronic structure.2. Synthesized a series of vanadium-substituted Keggin-type polyoxotungstate with differ capability of oxidization, which were used as materials reacted with dyes, such as crystal violet, methyl violet and rhodamine B, to obtain dye-polyoxometalate supermolecular systems respectively. Studied the supermolecular systems, we found that the interaction is increasing with the polarity of dye and oxidization of polyoxometalates are increasing, correspondingly the characteristic peaks move increasing. By analyzing the IR spectrum, we found the reaction activity center is at bridge-oxygen atom.