Low-temperature phase of hexaguanidinium hepta­molybdate monohydrate

The crystal structure of the title compound, [C(NH2)3]6[Mo7O24]·H2O, previously determined at room temperature in the monoclinic space group C2/c from Weissenberg techniques [Don & Weakley (1981 ▶). Acta Cryst. B37, 451–453], has been redetermined from low-temperature single-crystal data in the monoclinic space group P21/c. The asymmetric unit contains one hepta­molybdate anion, six guanidinium cations and one water mol­ecule of hydration. The anions and cations are linked by an extensive network of N—H⋯O hydrogen bonds

Synthesis and Structure of Hexatungstochromate(III), [H3CrIIIW6O24]6–

The hexatungstochromate(III) [H3CrIIIW6O24]6- (1) was synthesized in aqueous, basic medium by simple reaction of chromium(III) nitrate nonahydrate and sodium tungstate dihydrate in a 1:6 ratio. Polyanion 1 represents the first Anderson-Evans type heteropolytungstate with a trivalent hetero element. The sodium salt of 1 with the formula Na6[H3CrIIIW6O24]·22H2O (1a) was fully characterized in the solid state by single crystal XRD, FT-IR spectroscopy, and thermogravimetric analysis

Anomalous permeation of the [P5W30O110 ]15- polyoxoanion in polyelectrolyte multilayer films

International audienceThe integration of polyoxoanions into functional thin films is of major interest to increase their use as catalysts or to provide new properties to the films. The incorporation of polyoxoanions in polyelectrolyte multilayer (PEM) films has been widely used for such aims. In most investigations, the polyoxoanions were used as a component of the layering process and there is only limited work investigating the interactions of polyoxoanions with preformed PEM films. Herein, we investigated the incorporation of the 30-tungsto-5-phosphate [P 5 W 30 O 110 ] 152 polyoxoanion into PEM films made from hyaluronic acid (HA) and poly(allylamine hydrochloride) (PAH) as a function of the polyoxoanion's concentration. Surprisingly, we found an increased amount of incorporated [P 5 W 30 O 110 ] 152 upon a decrease in its bulk concentration. Confocal Raman microscopy allowed us to investigate the concentration profile of the polyoxoanion across films of about 3 mm in thickness. Homogeneous distribution was only found for films fed with polyoxoanions at the lowest bulk concentration, namely 1.2 6 10 26 M, whereas the films fed with solutions at higher concentrations (1.2 6 10 24 M) showed local enrichment in POM at the film-solution interface. We explain the lower amount of incorporated polyoxoanion at high bulk concentration by the formation of a polyoxoanion-rich barrier reducing further diffusion of the anions in the deeper part of the films

Vanadium-based polyoxometalate as new material for sodium-ion battery anodes

Affordable energy storage is crucial for a variety of technologies. One option is sodium-ion batteries (NIBs) for which, however, suitable anode materials are still a problem. We report on the application of a promising new class of materials, polyoxometalates (POMs), as an anode in NIBs. Specifically, Na6[V10O28]·16H2O is being synthesized and characterized. Galvanostatic tests reveal a reversible capacity of approximately 276 mA h g−1 with an average discharge potential of 0.4 V vs. Na/Na+, as well as a high cycling stability. The underlying mechanism is rationalized to be an insertion of Na+ in between the [V10O28]6− anions rather than an intercalation into a crystal structure; the accompanying reduction of V+V to V+IV is confirmed by X-ray Photoelectron Spectroscopy. Finally, a working full-cell set-up is presented with the POM as the anode, substantiating the claim that Na6[V10O28]·16H2O is a promising option for future high-performing sodium-ion batteries

Characterization of polyoxometalate I as an inhibitor of RNA-dependent RNA polymerase of Foot and Mouth Disease virus [abstract]

Abstract only availableFoot and Mouth Disease (FMD) is a highly contagious disease that affects a variety of domesticated cloven-hoofed animals including cattle, swine, sheep and goats, as well as several wild animal species. FMD outbreaks are currently controlled with mass-extermination of livestock. The financial cost of potential outbreaks would be immense. This disease is caused by foot-and-mouth disease virus (FMDV), a non-enveloped, single-stranded, positive-sense RNA virus. The purpose of our investigation is to identify chemicals that interfere with the replication of FMDV. As part of this effort we have identified a polyoxometalate inhibitor (polyoxometalate I). We have cloned, expressed and purified FMDV RdRp. We use steady-state kinetic experiments and polymerization assays to characterize the inhibitory activity of the polyoxometalate I, determining the precise inhibitory potential and the mechanism of inhibition. Preliminary results show that polyoxometalate I inhibits the FMDV RdRp surprisingly efficiently with an IC50 of 0.5uM. Current experiments are focusing on a detailed kinetic characterization of the mechanism of action for this inhibitor. This research may provide insights that lead to new treatment options to prevent the further spread of FMD to unaffected animals.USD

Antineuroblastoma potential of polyoxopalladate(II)

Background: Polyoxometalates are a class of anionic, polynuclear metal-oxo clusters reported as promising in vitro and in vivo antitumor agents for several decades. The aim of this study was to investigate the antineuroblastoma potential of the polyoxopalladate(II) nanocube Na8[Pd13As8O34(OH)6]・42H2O (Pd13). Material and methods: All experiments were performed on human neuroblastoma cell line, SH-SY5Y. The number of viable cells after the treatment with Pd13 was assessed using an acid phosphatase viability assay. The level of superoxide ion, mitochondrial membrane potential, pan-caspase activity, acidic intracellular vesicles content, and the cell cycle was determined by flow cytometry. Results: The obtained results suggest that Pd13 caused a significant decrease in cell viability with IC50 values of 7.7 µM (24 h) and 4.4 µM (48 h). Pd13 induced depolarization of mitochondrial membrane (2 h), followed by ~ 30% increase in the production of the superoxide ion (O2-) 4 h after treatment. An increase (~ 30%) in pancaspase activation and disturbance of neuroblastma cell cycle were observed after 24 h treatment. Namely, Pd13 caused an increase (14.4%) in the number of cells with fragmented nuclear DNA (SubG0), a decrease (%) of cells in the G1 phase, and an increase (%) in the S phase, all suggestive of cell cycle arrest. Finally, Pd13 increased the orange to green fluorescence ratio for ~ 45% 24 h after treatment, supporting intracellular acidification. Conclusion: The polyoxopalladate, Pd13 can be regarded as a promising antineuroblastoma agent which induces oxidative stress, and causes pan-caspase activation, DNA fragmentation and cell cycle arrest, which are all hallmarks of apoptotic neuroblastoma cell death.5th Congress of the Serbian Association for Cancer Research with International Participation SDIR-5, Virtual event, December 3, Belgrade, 2021

Cytogenotoxicity assessment of polyoxopalladates(II) as promising antileukemic drug candidates

Polyoxopalladates(II) (POPs) are discrete, anionic palladium(II)- oxo nanoclusters that possess features of both conventional polyoxometalates (POMs) and palladium(II), which were shown to exhibit promising antitumor properties. In this study, in vitro cyto- and genotoxicity evaluation was performed on normal non-target human blood cells using two isostructural POPs with tetravalent metal ions (SnIV, PbIV) encapsulated in the cuboid Pd12-oxo host, Na12[SnO8Pd12(PO4)8]·43H2O (SnPd12) and Na12[PbO8Pd12(PO4)8]·38H2O (PbPd12), with confirmed in vitro antileukemic actions against HL-60 cell line. For this purpose, whole blood samples were exposed to the POPs, at concentrations of ≈ IC50 (24 h) values, resulting in cytotoxicity in HL-60 cells for 24 h at 37 °C. The cytotoxicity studies were performed on human peripheral blood mononuclear cells which were stained with acridine orange and ethidium bromide, and then viewed under a fluorescence microscope. The genotoxicity was tested in whole blood by the alkaline comet assay (microgel electrophoresis). The results of the cytotoxicity evaluation and the comet assay demonstrated that none of the tested POPs, within the investigated concentration range 12.5 – 50 µM, resulted in a statistically significant modulation of blood cell viability as well as DNA damage, expressed as % of tail DNA (relative increase of tail DNA), compared to the untreated controls. Therefore, the promising antileukemic drug candidates, SnPd12 and PbPd12, can be considered as selective and safe from a cytogenotoxicity point of view.15th international conference on fundamental and applied aspects of physical chemistry : September 20-24, Belgrade

Selected polyoxopalladates as potential antitumor drug candidates

Background: Polyoxo-noble-metalates, a class of molecular noble metal-oxo nanoclusters that combine features of both polyoxometalates and noble metals, are a promising platform for the development of nextgeneration antitumor metallodrugs. The aim of this study was to evaluate the antineuroblastoma potential of three novel polyoxopalladates. Material and methods: All experiments were performed on human neuroblastoma cell line, SHSY5Y. The three polyoxo-noble-palladates Na4[SrPd12O6(OH)3(PhAsO3)6(OAc)3] ・2NaOAc・32H2O (SrPd12), Na12[SnIVO8Pd12(PO4)8]·43H2O (SnPd12) and Na12[PbIVO8Pd12(PO4)8]·38H2O (PbPd12) were investigated in our study. The viability of neuroblastoma cells after 24h treatment was assessed using an acid phosphatase assay. The level of superoxide ion, mitochondrial membrane potential, pan-caspase activity, cell cycle analysis and acidic vesicles content were determined by flow cytometry using appropriate fluorochromes. Results: Calculated IC50 (μM; 24h) values were 75.8 ± 6.7 (SrPd12) and >>100 (SnPd12 and PbPd12), selecting SrPd12 as the most efficient. SrPd12 did not affect the mitochondrial membrane potential and superoxide production in neuroblastoma cells after short (2 h and 4 h) exposure. Also, it did not induce an increase in the number of neuroblastoma cells with fragmented DNA content, but displayed the cell cycle arrest: the ~ 23% reduction of neuroblastoma cells in G0/G1 phase and the ~ 17% increase in S phase. The treatment with SrPd12 did not increase the level of acidic vesicles but it increased the activity of caspases five-fold. Conclusion: Only SrPd12 exhibited a satisfactory antineuroblastoma action by inducing caspase activation and neuroblastoma cell cycle arrest.5th Congress of the Serbian Association for Cancer Research with International Participation SDIR-5, Virtual event, December 3, Belgrade, 2021