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The first example of Rh-substituted organic–inorganic hybrid arsenotungstate [H2N(CH3)2]8{[Na(H2O)4]NaAs2W22(CH3COO)2O76 Rh2(N(CH3)2)2}·H2O (1) synthesised in an aqueous solution by the conventional method is reported. Two [Rh(N(CH3)2)]3+ fragments are imbedded into the vacancy of the [NaAs2W22(CH3COO)2O76]15− unit by Rh–As bonds [2.439(1) Å], which are observed in POM chemistry for the first time. [ABSTRACT FROM AUTHOR]

Two mononuclear Dy3+ compounds [Dy(bmbpen-F)X] (X = Cl, 1; Br, 2) with a pentagonal bipyramidal (PBP) geometry were obtained from N,N′-bis-(5-methyl-2-hydroxybenzyl)-N,N′-bis(5-fluoro-2-methylpyridyl)ethylenediamine (H2bmbpen-F) and dysprosium halides. The magnetic anisotropy and single-molecule magnet (SMM) behavior of these PBP compounds were regulated by introducing both electron-withdrawing F atoms into the equatorial pyridine rings and electron-donating –CH3 groups into the axial phenolic hydroxyl rings. The results of magnetic characterization show that 1 and 2 exhibit single molecule magnet behavior with magnetization reversal barriers of 990(13) and 1189(16) K under a zero dc external field and magnetic hysteresis loops up to 26 K and 36 K, respectively. The results of ab initio calculations are consistent with the experimental observations, confirming that the simultaneous introduction of electron-withdrawing groups into the equatorial positions and electron-donating groups into the axial positions can lead to PBP Dy-SMMs with improved properties. [ABSTRACT FROM AUTHOR]

Three structurally intriguing polyoxoniobates (PONbs) based on the trivacant B-type α-Keggin ion {TeNb9O33}, H4K(CN3H6)2{[Cu4(2,2′-bipy)4(H2O)2][TeNb9V2O37]}·29H2O (1, 2,2′-bipy = 2,2′-bipyridine), H0.5K5Na2.5{[Cu(en)H2O]3[TeNb9V3O39]}·10H2O (2, en = ethylenediamine), and K3Na5{[Cu(1,3-dap)H2O]3[TeNb9V3O39]}·11H2O (3, 1,3-dap = 1,3-diaminopropane), are assembled by the conventional aqueous solution methods using a series of N-containing organic ligands. In 1, each of the two {VO4} units is attached to two coplanar NbO6 octahedra on the {Nb3O13} cluster of the {TeNb9O33} unit. Differently, three {VO4} units in 2 and 3 are linked to two edge-sharing NbO6 octahedra, respectively. Compounds 1–3 represent the first oxo NbTeV clusters and also the first vanadoniobates based on the trivacant Keggin PONb units. All three compounds were characterised by single-crystal X-ray structural analysis, TGA and IR, ESI-MS and 51V NMR spectroscopy. Furthermore, the magnetic properties of compounds 1 and 2 were also studied. [ABSTRACT FROM AUTHOR]

Because indiscriminate antibiotic usage has driven bacterial evolutionary selection so that there is increasing microbial resistance, there is an urgent need to develop new generations of effective antibacterial agents. Herein, we developed a facile and green strategy for the preparation of a nanostructured Fe3O4@PDA@Ni-DT composite by anchoring decatungstate-based nickel(II) complex (Ni-DT) ([Ni(HL)2]2[W10O32]·4H2O, HL = 2-acetylpyridine thiosemicarbazone) onto hybrid Fe3O4@PDA (PDA = polydopamine) nanosheets. Compared with pristine Ni-DT and Fe3O4@PDA, the Fe3O4@PDA@Ni-DT composite killed 99.3% of Gram-negative Escherichia coli and 98.8% of Gram-positive Staphylococcus aureus bacteria. Notably, the composite showed potent antibacterial activity against antibiotic-resistant E. coli bacteria (ampicillin and kanamycin). The composite retained excellent recyclable performance due to the introduction of Fe3O4 nanoparticles. The detailed antibacterial mechanism used by the hybrid Fe3O4@PDA@Ni-DT composite against E. coli indicates that the nanostructured composite played a significant role in destroying the cell membrane of bacteria, inhibiting the enzymatic activity of bacteria, and increasing bacteria-destroying oxidative stress. The current work provides an effective strategy to synthesize multifunctional decatungstate-based material for highly effective and reusable antimicrobial agents. [ABSTRACT FROM AUTHOR]

A nanoscale polyoxoniobate based on trivalent nickel complex and Lindqvist-type cluster, [Ni(en)3]2[H2Nb6O19]·8H2O (abbreviated as NEN) (en = ethylenediamine, C2H8N2) has been synthesized and structurally characterized by elemental analyses, IR spectrum, UV–visible spectra, X-ray photoelectron spectrum (XPS), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Structural analysis shows that NEN is an ionic compound, in which the cations are two trivalent nickel complexes [Ni(en)3]3+ and the anion is a Lindqvist-type polyoxoniobate [Nb6O19]8− cluster. Notably, NEN can catalyze the production of reactive oxygen species efficiently in aqueous solution system. [ABSTRACT FROM AUTHOR]

A 72-nuclearity niobium cluster was synthesized, in which two {CuNb26O76} clusters and one {Nb20O59} cluster are fused in a triangular fashion, resulting in a {Nb12} cavity. Further, the simple nature of the species allowed its investigation by ESI-MS analysis, yielding two subunits with time. [ABSTRACT FROM AUTHOR]

The development of new heterogeneous catalysts for Knoevenagel condensation reaction is critical for practical applications. Herein, we prepared three organophosphonate-functionalized polyoxomolybdates, Cs2Na9H9[{Co(H2O)4}(TeMo6O21)2{Co(OOCCH2NCH2PO3)2}3]·41H2O (1), Cs2Na8[H6{Co(H2O)4}3(SeMo6O21)2{Co(OOCCH2NCH2PO3)2}3]·31H2O (2) and Cs2Na9H3[H6{Ni(H2O)4}(SeMo6O21)2{Ni(OOCCH2NCH2PO3)2}3]·28H2O (3), which exhibit high catalytic activity for gram-scale Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate. Especially, under the optimal conditions, compound 1 can achieve a satisfactory yield (98%) and show high TON value (1960), which is superior to that of compounds 2 and 3. Notably, the TON value is much higher than that of previously reported catalysts. Such high catalytic performance could be attributed to the co-existence of Lewis acid and Lewis base sites in catalysts. In addition, based on substrates screening and recyclability tests, 1 has exhibited broad catalytic generality and good recyclability. [ABSTRACT FROM AUTHOR]

An organic-inorganic hybrid polyoxometalate (POM) based on bi-nuclear copper complexes and Dawson-type phosphotungstate (POT) [CuL(H2O)][CuL]2[P2W18O62]·3H2O (abbreviated as CPW) (L = 2-(1H-pyrazol-3-yl)pyridine) was synthesized and structurally characterized by IR spectrum, and single-crystal X-ray diffraction. Structural analysis indicated that CPW is nanoscale molecule and extends into a two-dimensional layer, in which three bi-nuclear copper complexes are substituted at different sites of Dawson-type POT and joined adjacent POT fragments together. Notably, CPW can efficiently catalyze the production of reactive oxygen species. [ABSTRACT FROM AUTHOR]

Two new members of highly charged Silverton archetype [NaM12O42]11− were demonstrated in the 3D POM-based frameworks Na3[NaM12O42(Ru(DMSO)3)4]·13H2O (M = Mo (1), W (2)), where the unusual icosahedron coordination of a Na+ ion incubated as a heteroatom is reported for the first time in topical POMs. Furthermore, 23Na NMR was applied to certify the interpretation of X-ray diffraction data concerning Na localization. Additionally, the porous nature of the frameworks 1 and 2 has also been investigated. [ABSTRACT FROM AUTHOR]

Key message: New powdery mildew resistance gene Pm68 was found in the terminal region of chromosome 2BS of Greek durum wheat TRI 1796. The co-segregated molecular markers could be used for MAS. Durum wheat (Triticum turgidum L. var. durum Desf.) is not only an important cereal crop for pasta making, but also a genetic resource for common wheat improvement. In the present study, a Greek durum wheat TRI 1796 was found to confer high resistance to all 22 tested isolates of Blumeria graminis f. sp. tritici (Bgt). Inheritance study on the F1 plants and the F2 population derived from the cross TRI 1796/PI 584832 revealed that the resistance in TRI 1796 was controlled by a single dominant gene, herein designated Pm68. Using the bulked segregant RNA-Seq (BSR-Seq) analysis combined with molecular analysis, Pm68 was mapped to the terminal part of the short arm of chromosome 2B and flanked by markers Xdw04 and Xdw12/Xdw13 with genetic distances of 0.22 cM each. According to the reference genome of durum wheat cv. Svevo, the corresponding physical region spanned the Pm68 locus was about 1.78-Mb, in which a number of disease resistance-related genes were annotated. This study reports the new powdery mildew resistance gene Pm68 that would be a valuable resource for improvement of both common wheat and durum wheat. The co-segregated markers (Xdw05–Xdw11) developed here would be useful tools for marker-assisted selection (MAS) in breeding. [ABSTRACT FROM AUTHOR]