| Polyoxometalates （Polyoxometalate, abbreviation: POMs） is commonly knownas polyacids, is a kind of metal-oxo clusters compounds by the early transition metalions through the oxygen formed connecting. Polyoxometalates have favorableapplications prospect in diverse areas such as medicine, catalysis, materials science,analytical chemistry owing to their incredible structural diversity and interestingproperties. Polyoxoniobates （PONb） are an important subfamily of polyoxometalates（POMs）. They have potential applications in the study of virology, nuclear wastedisposal and photocatalytic decomposition of water due to the high negative chargeand the unique nature of high alkaline. The hydrothermal method is an effectivestrategy for the synthesis of polyoxoniobates. The temperature of the reaction system,the pH value, the ratio of raw materials and other conditions are controlled using thehydrothermal synthesis technique to gain many novel structure polyoxoniobates.In this paper, we used hydrothermal synthesis and chose [Nb6O19]8-alkali metalsalts, sodium silicate and copper-ethylenediamine organometallic complexes as thebasic raw material. We explored the optimal experimental conditions and thesynthesis of law, successfully obtained a potassium, sodium sandwich-typeheteropolyniobate compound under the alkaline conditions:[Cu（en）2][Cu（en）2（H2O）2]4Na4K4[（SiOH）2Si2Nb16H5O54]2·40H2O （1）. Single-crystalX-ray diffraction tests showed that the anionic portion of the compound is asandwich-type heteropolyniobate, composed of two [（SiOH）2Si2Nb16H2O54]12-unitsconnected through both Na+and four K+. The conditions of the synthesis of thecompound are discussed, and the structure and nature of the compounds furthercharacterized by elemental analysis, IR, solid diffuse reflectance, thermal gravimetricanalysis and other means. |
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