| Polyoxometalates (POMs) are regarded as one of the excellent building blocks due to their nano-size, unique structural variety and interesting physicochemical properties, which have potential applications in the fields of photochemistry, electronic, magnetic and solid acid catalytic materials. As an important part of POMs, high-nuclearity heteropolytungstate clusters have received much attention and a series of lacunary heteropolytungstate POMs such as monovacant divacant{β-SiW11}, divacant{γ-SiW10}, trivacant{A-PW9}, and the hexavacant{P2W12} etc can be found. One of the remarkable approaches in the construction of high-nuclearity metal-oxygen clusters is to combine the lacunary POMs with transition-metal ions. On the other hand, the self-assembly of the lacunary POMs via terminal oxygen atoms has been proved an efficient method for synthesizing different dimensional POMs. In addition, POMs decorated with transition-metal complex (TMC) are of great interest because the properties of POMs and coordination complex can be brought together, which is anticipated to obtain new heteropolytungstate clusters with a variety of structural motifs and interesting properties, which should lead to new functional materials.In this paper, we selected lacunary POMs [γ-SiW10O36]8- and [A-PW9O34]9 as precursors synthesizing eleven novel heteropolytungstate clusters 1-11. In addition, the 4,4’-bipydidine-N,N’-dioxide (dpdo) has been utilized to construct two POM-based organic-inorganic hybrid compounds 12 and 13. The compounds have been structurally characterized by IR, UV-vis, elemental analysis, XRPD and single-crystal X-ray diffraction. Moreover, the electrocatalysis and photocatalytic activities for RhB degradation under UV light irradiation of products have also been investigated in detail. This paper has divided into three chapters which were introduced as follows:(1) We select the divacant heteropolyanion [γ-SiW10O36]8- as precursor, synthesizing a cyclic trimer polyoxometalate K9Na3[EMIm][Co2(SiW10O37)]3Br·3H2O (1) via ionothermal syntheis, in which three{γ-SiW10} units are connected by Co6 cluster. Three M4-substituted (M= Co, Ni) sandwich transition-metal-substituted polyoxometalates (TMSPs) H8[PMIm]2[Co2(H2O)12Co4(H2O)2(OH)2(SiW10O37)2]·12H2O (2), H10[Ni2(H2O)12Ni4(H2O)2(OH)2(SiW10O37)2]·6H2O (3), H8[PMIm]2[Ni2(H2O)12Ni4(H2O)2(OH)2(SiW10O37)2]·12H2O (4) have been synthesized by the reaction of the divacant heteropolyanions [γ-SiW10O36]8- and transition-metal ions Co2+, Ni2+ in the mixed solvents of H2O and ionic liquids. A novel high-nuclearity metal-oxygen cluster H16K2[Cu13(OH)4(H2O)10(SiW8O31)4]·12H2O (5) has been synthesized via the reaction of Cu2+ and [γ-SiW10O36]8- under has been conventional solution synthesis. The magnetic properties of 3 and 5 have been studied, indicating antiferromagnetic and ferromagnetic interactions between metal atoms, respectively.(2) The trivacant polyanion [A-PW9O34]9- has been selected as starting materials, a one-dimensional compound H17Na4(bipy)3(PW7Co5O39)·2H2O (6) has been synthesized in hydrothermal condition, in which the adjacent{PW7CO5O39} unites are connected by terminal oxygen atoms. Three compounds H5Na4[EMIm]3[(PW11Co0·9)(PW11CoO40)] (7), H8Na8[EMIm]4[(PW10.5Cu1.5O39)(PW12O40)]2·2H2O (8), H12[EMIm]4[(PW11MnO39)(PW10Mn2O4o)]·H2O (9) have been synthesized in mixed solvents of H2O and ionic liquids, exhibiting a dimer structure based on two Keggin-typed polyanions which are connected by a terminal oxygen atom. In addition, two sandwich structures H2[EMIm]8[Mn4(H2O)2(PW9O34)2]·2H2O (10) (EMIm+:1-ethyl-3-methylimidazolium cation) and H4[PMIM]6[MnPW11O39]2·H2O (11) (PMIM+:1-ethyl-3-pentylimidazolium cation) containing Mn4 and Mn2, respectively, have been synthesized by changing the length of the substituent from the ionic liquids. The optical properties imply the energy bands (Eg) of compounds 6-9 are 2.41 eV,2.45 eV,3.64 eV and 3.78 eV, respectively. The Eg values of 8 and 9 are similar to the semiconductor materials ZnS (3.60 eV) and SnO2 (3.70 eV), implying that compounds 8 and 9 are wide band-gap semiconductor materials. Compounds 8-11 exhibit good electrocatalytic activity toward the reduction of nitrite.(3) Two Co-dpdo containing POM-based organic-inorganic hybrids H2[Co2(dpdo)3(H2O)4(P2W18062)]·3H20 (12) and H7[(PW11CoO39)dpdo]·3H2O (13) have been synthesized via the reaction of Co2+,dpdp and the lacunary polyoxoanions [A-PW9O34]9- and [P2W12O48]14-, repectively. The photocatalytic activities for RhB degradation under UV lights have been investigated. The degradation rates for 12 and 13 are 58.4% and 37.4%, repectively. And the electrocatalytic activities of 12 for reduction of nitrite in the aqueous solution have also been investigated, suggesting that 12 shows good electrocatalytic activity toward the reduction of nitrite. |
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