| POMs (Polyoxometalates) acted as a kind of important anion building block are applied widely in construction of original and functional crystalline inorganic-organic hybrids. With abundant and defined structure, POMs such as classical Keggin and Dawson types still attract much interest partly based on their large domains of applications, ranging from catalysis, medicine, electrochemistry, photochromism, to magnetism etc. In parallel to POMs, inorganic-organic hybrids based on POMs have gained the attention of researchers, especially in catalytic application. POM anions represent a well-defined library of inorganic building blocks with Lewis and Br(?)nsted acidity that can be utilized to build effective solid-acid catalysts for a series of chemical reactions. In this work, Keggin POMs are used as one of basic building blocks to synthesize twelve compounds with organic ligands and metal salts, and conduct structural characterization and preliminary exploration of catalytic or antibacterial property.1. We select Keggin{PW12}, AgNO3 and rigid N-donor bridging ligands, bpy 2,2-bipyridine, H2biim= 2,2-biimidazole and pytz= 4-(1H-tetrazol-5-yl)pyridine), to synthesize three crystalline compounds (1,2,3), which exhibit light-driven degradation of dyes and antibacterial properties. Besides, we synthesize compound 4 by using H2biim to prove that nitration that happens to compound 2 is not ascribed to impurity of H2biim. {Ag3(bpy)6[PW12O40]} (1) {Ag5(H2biim)2(Hbiim-NO2)2[PW12O40]} (2) {Ag7(pytz)4[PW12O40]} (3) {Cu2.5(H2biim)5(H2O)[BW12O40]}ˇ3H2O (4)Structural analysis and characterization to compounds 1-3 show structures of compounds varies from low dimension to high dimension due to change of coordination modes from unilateral chelating ligand to all-around ligand, and frameworks of compounds are becoming more complicated and fascinating. Furthermore, it is noteworthy that nitration happens to compound 2 during the hydrothermal condition, which is quite rare. Photo-degradation of organic dyes and antibacterial activities measurements indicate compounds 1-3 all have dual functions, which not only can catalyze degradation reaction of RhB, MB and AR dyes under UV irradiation, but also can kill negative Escherichia coli and positive Streptococcus agalactiae.2. We synthesize three organic ligands, 1,4-bis(1,2,4-triazol-1-lmethyl)benzene (1,4-BBTZ), (1,3-BBTZ) and 1,4-bis(3-pyridyloxy)-benzene (L). In addition, the use of Keggin{BW12} anion with higher negative charges makes it more likely to combine with metal-organic moieties. Secondly, it is easily prepared but less studied. Based on adjustment of temperature, we obtain four compounds (5,6,7,8) constructed with{BW12} and BBTZ-Cu. Also, we use L and{SiW12} to synthesize compound 9. {Cu?3Cl(1,4-BBTZ)5[BW12040](H20)2}ˇ6H2O (5) {Cu?3Cu?(1,4-BBTZ)5[BW12040](H20)ˇH20 (6) {Cu?Cu? (1,3-BBTZ)5[BW12040]}ˇH2O (7) {Cu?5(1,3-BBTZ)4[BW12040]}ˇ4H2O (8) {Cu?2(L)4[SiW12O40]}ˇ6H2O (9)Crystallographic analyses show compounds 5-7 are three-dimensional structures,8 and 9 are two-dimensional structures. Through adjustment of ligands and temperature, we analyze their structures and speculate photocatalytic property and emphatically investigate compounds 5 and 6. Results indicate that compound 6 with narrow band-gap size exhibits more favorable efficiency of photocatalytic activity under visible light irradiation than compound 5.3. We use high temperature strategy again to assemble three isostructural compounds 10, 11,12 under 190-195? by adopting 1,2,4-1H-triazole (1H-trz), CuCl2 and Keggin POMs. {Cu?12Cl(trz)8PW12O40]} (10) {Cu?12Cl(trz)8[PMo12040]} (11) {Cu?12Cl(trz)8[HSiW12O40]} (12)All copper atoms are in+1 oxidation state in the compounds 10-12, and these compounds can catalyze degradation of dyes under visible light irradiation. Its relevant photocatalytic mechanism is also delicately investigated. All of the title compounds display high heat stability, and excellent acid and alkali resistance. |
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