Recent advances of decatungstate photocatalyst in HAT process

The decatungstate anion (W10O324-) appears to exhibit especially interesting properties as a photocatalyst. Because of its unique photocatalytic properties, it is now recognised as a promising tool in organic chemistry. This study examines recent advances in decatungstate chemistry, primarily concerned with synthetic and, to some degree, mechanistic challenges. In this short review we have selected to give a number of illustrative examples that demonstrate the various applications of decatungstate in the hydrogen atom transfer (HAT) process.

Synthesis and characterization of a new copper-based polyoxomolybdate and its catalytic activity for azide-alkyne cycloaddition reaction under UV light irradiation

A new organic-functionalized Cu-based Anderson-type polyoxomolybdate, namely (C7H15N4)2[Na(H2O)4]2[C6H12CuMo6N2O24]·2(H2O) (CuII-POM), was synthesized via a simple one-pot reaction and subsequently characterized using a range of analytical and spectral techniques. Structural investigation by single crystal X-ray diffraction analysis revealed that the polyanion component of the synthesized compound (i.e. [C6H12CuMo6N2O24]4-) possesses a δ-isomer Anderson-type structure, which is surrounded by four lattice water molecules and four [C7H15N4-NaH15(H2O)8]4+ cations in the crystal packing arrangement. The resulting double-sided tris-functionalized Anderson-type compound can function as highly effective heterogeneous photocatalysts for the copper(I)-catalyzed Huisgen azide-alkyne cycloaddition (Cu-AAC) reaction of terminal alkyne, benzyl halides, and sodium azide (acts as the azidonation and reducing agent) in aqueous media. Ultraviolet light irradiation enhances the catalytic activity of CuII-POM ~ 4.4 times of the "off" situation under reaction conditions of 0.00239 mmol cat., 80 °C, 8 h, 2 mL H2O, So that the isolated yields for the AAC reaction involving a variety of terminal alkynes and benzyl halides using the CuII-POM catalyst ranged between 19-97%. The current study is the first report about using an efficient and economical Cu(II)-POM/UV/NaN3 catalytic system in the Cu-AAC reaction and reveals its significant potential for applying to other Cu(I)-catalyzed reactions.

Development and application of decatungstate catalyzed C-H 18F- and 19F-fluorination, fluoroalkylation and beyond

Over the past few decades, photocatalytic C-H functionalization reactions have received increasing attention due to the often mild reaction conditions and complementary selectivities to conventional functionalization processes. Now, photocatalytic C-H functionalization is a widely employed tool, supporting activities ranging from complex molecule synthesis to late-stage structure-activity relationship studies. In this perspective, we will discuss our efforts in developing a photocatalytic decatungstate catalyzed C-H fluorination reaction as well as its practical application realized through collaborations with industry partners at Hoffmann-La Roche and Merck, and extension to radiofluorination with radiopharmaceutical chemists and imaging experts at TRIUMF and the BC Cancer Agency. Importantly, we feel that our efforts address a question of utility posed by Professor Tobias Ritter in "Late-Stage Fluorination: Fancy Novelty or Useful Tool?" (ACIE, 2015, 54, 3216). In addition, we will discuss decatungstate catalyzed C-H fluoroalkylation and the interesting electrostatic effects observed in decatungstate-catalyzed C-H functionalization. We hope this perspective will inspire other researchers to explore the use of decatungstate for the purposes of photocatalytic C-H functionalization and further advance the exploitation of electrostatic effects for both rate acceleration and directing effects in these reactions.

Bifunctional K3PW12O40/Graphene Oxide-Modified Separator for Inhibiting Polysulfide Diffusion and Stabilizing Lithium Anode

Lithium-sulfur (Li-S) batteries are considered as promising candidates for next-generation batteries due to their high theoretical energy density. However, the practical application of Li-S batteries is still hindered by several challenges, such as the polysulfide shuttle and the growth of lithium dendrites. Herein, we introduce a bifunctional K3PW12O40/graphene oxide-modified polypropylene separator (KPW/GO/PP) as a highly effective solution for mitigating polysulfide diffusion and protecting the lithium anode in Li-S batteries. By incorporating KPW into a densely stacked nanostructured graphene oxide (GO) barrier membrane, we synergistically capture and rapidly convert lithium polysulfides (LiPSs) electrochemically, thus effectively suppressing the shuttling effect. Moreover, the KPW/GO/PP separator can stabilize the lithium metal anode during cycling, suppress dendrite formation, and ensure a smooth and dense lithium metal surface, owing to regulated Li+ flux and uniform Li nucleation. Consequently, the constructed KPW/GO/PP separator delivered a favorable initial specific capacity (1006 mAh g-1) and remarkable cycling performance at 1.0 C (626 mAh g-1 for up to 500 cycles with a decay rate of 0.075% per cycle).

Photoinduced electron transfer between a noble-metal-free [Mo6I8Cl6]2- cluster and polyoxometalates

Evidence for photoinduced intermolecular electron transfer from the excited state of the [Mo6I8Cl6]2- electron-rich cluster to polyoxometalates (POMs) is reported. We demonstrate that the global charge density of POMs affects the efficiency of electron transfer. This work paves the way for the rational design of photocatalytic systems using cluster-based complexes as robust noble-metal-free photosensitizers.

Novel morphological mono-metallic substituted polyoxometalate immobilized 3-(aminopropyl)-imidazole photocatalysts for visible-light driven degradation: Anti-bacterial activity, membrane bacterial activity applications

A novel keggin-type tetra-metalates substituted polyoxometalate was functionalized by 3-(aminopropyl)-imidazole (3-API) supporting a ligand substitution method. In this paper, polyoxometalate (POMs) (NH₄)₃ [PMo₁₂O₄₀] and transition metal substituted of (NH₄)₃ [{PM^IVMo₁₁O₄₀}.(H₂O)] (M = Mn, V) are used as one of the adsorbents. The 3-API/POMs hybrid have been synthesized and used as adsorbent for the photo-catalysis of azo-dye molecule degradation after visible-light illumination as a simulated organic contaminant in water. The transition metal (M = M^IV, V^IV) substituted keggin-type anions (MPOMs) were synthesized, which reveals the degradation of methyl orange (MO) of about 94.0 % and 88.6 %. Immobilizing high redox ability POMs as an efficient acceptor of photo generated electron, on metal 3-API. In the presence of visible light irradiation result reveals that 3-API/POMs (89.9 %) have incredibly achieved after certain irradiation time and at specific conditions (3)-API/POMs; photo-catalysts dose = 5mg/100 ml, pH = 3 and MO dye concentration = 5 ppm). As the surface of POM catalyst has strong absorption of azo-dye MO molecule engaged as a molecular exploration through photo catalytic reactant. From the SEM images it is clear that the synthesized POMs based materials and POMs conjugated MO have varieties of morphological changes observed such as flakes, rods and spherical like structures. Anti-bacterial study reveals that the process of targeted microorganism occur higher activity against pathogenic bacterium for 180 min of visible-light irradiation is measured in terms of zone of the inhibition. Furthermore, the photo catalytic degradation mechanism of MO using POM, metaled POMs and 3-API/POMs also has been discussed.

Phosphotungstic Acid-treated Picrosirius Red Staining Improves Whole-slide Quantitative Analysis of Collagen in Histological Specimens

We tried to prevent nonspecific nuclear staining (NS-NS) of picrosirius red (PSR) staining by treating the specimens with one of the heteropoly acids phosphotungstic acid (PTA). We analyzed a total of 35 cases of non-cancerous liver tissue for fibrosis and NS-NS under PSR-alone, phosphomolybdic acid (PMA)-pretreated PSR (PMA + PSR), or PTA-pretreated PSR (PTA + PSR) condition. In addition, we analyzed the photosensitivity of PMA or PTA single stain specimens. PTA + PSR significantly suppressed NS-NS compared with PSR. The color of the specimens did not change into blue by 30 times the exposure to whole slide scanner (WSS) light. The PTA + PSR condition showed the highest correlation with the Ishak score (pathological evaluation of liver fibrosis) compared with other conditions. Furthermore, Sirius Red-positive percentage (SRP%) in PSR was increased in the NS-NS observed cases. SRP% in PMA + PSR was significantly affected by WSS light exposure time. Moreover, the deposition of non-polarized PSR-stained substances (NP-PSR+S) clinging to the collagen fibers potentially explains why SRP% seemed bigger under PSR than PTA + PSR. Our protocol enabled us to analyze the whole slide image of PSR staining by high magnification, which would contribute to the accurate analysis of collagen amount in the tissue sections.

Controlled Assembly of Ru-Containing Polyoxometalates for Photocatalytic Activity of the Primary Amine Coupling Reaction

Three Ru-induced structural interconversion polyoxometalates (POMs), Na₁₃H₅[Ru₄(H₂O)₂(Cl)₂(WO₂)₄(AsW₉O₃₃)₄]·43H₂O (1), K₅Na₉H₈[Ru₂(WO₂)₄(AsW₉O₃₃)₄]·50H₂O (2), and KNa₁₃H₁₄[(WO₂)₄(AsW₉O₃₃)₄]·34H₂O (3), were successfully synthesized and thoroughly characterized. Interconversion of structures was accomplished by changing the number of active sites for compounds 1-3. All three compounds contain one {As₄W₄₀O₁₄₀} unit, showing similar structural characteristics except for the active center number (Ru). Interestingly, compound 1 [turnover number (TON)= 486; turnover frequency (TOF)= 20 h^-1] showed highly efficient photocatalysis in achieving oxidative coupling of primary amines. Compound 2 (TON = 406, TOF = 17 h^-1) was also found to promote the oxidative coupling with relatively poor efficiency; however, compound 3 (TON = 178; TOF = 7.4 h^-1) had no obvious contribution to the coupling reaction system, and a chain of evidence indicates that the catalytic performances are strongly dependent on element contents of active sites. Furthermore, the Ru-containing POM-based photocatalysts are conveniently recyclable and reusable during the photocatalytic processes. This study demonstrates the possibility of tuning the catalytic efficiency and stability of POM-based photocatalysts by well designing and controlling their structures. The possible reaction mechanism for the photocatalysis synthesis of imine product is also proposed based on experimental studies.

Binuclear Ru(III)-Containing Polyoxometalate with Efficient Photocatalytic Activity for Oxidative Coupling of Amines to Imines

A novel binuclear ruthenium-based polyoxometalate, K₆H[{Ru₂Cl(H₂O)(CH₃COO)₂}{WO(H₂O)}₂(PW₉O₃₄)₂]·14H₂O (1), was successfully synthesized by the conventional hydrothermal method. Compound 1 was well-characterized by single-crystal X-ray diffraction, X-ray powder diffraction (PXRD), infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), electrospray ionization-mass spectrometry (ESI-MS), thermogravimetric analyses (TGA), and elemental analysis. The structural unit of compound 1 contains two [A-α-PW₉O₃₄]^9- building blocks at the upper and lower positions connected by two W atoms and two Ru atoms, where the W atoms and Ru atoms are arranged in a trapezoidal arrangement and the Ru atoms are bridged by acetic acid. Furthermore, compound 1 features characteristic absorption bands in the visible region, which allows the investigation of its photocatalytic properties in visible light. Under simulated sunlight radiation (λ > 400 nm), compound 1 exhibits high photocatalytic activity and good circularity toward the oxidative coupling of amines to imines at room temperature with O₂ as the sole oxidant.

Merging the chemistry of metal-organic and polyoxometalate clusters into an enhanced photocatalytic material

The combination of a zirconium metal-organic cluster and a Keggin type polyoxotungstate into a compound of formula [Zr6(µ3-O)4(µ3-OH)4(µ-OOCC6H5)8(H2O)8][SiW12O40] led to a chemically and photochemically stable porous material in which a...

Reaction of H2 with polyoxometalate supported Rhodium(0) and Iridium(0) nanoparticles in aqueous suspensions: a kinetic study

The mechanism of the reaction between Rh0 and Ir0 NPs with H2 was measured in the absence of an electrical bias via monitoring the catalytic reduction of PW12O403− and it was compared to the previous results of Pt0 NPs.

Time-Resolved Spectroscopy and High-Efficiency Light-Driven Hydrogen Evolution of a {Mo3 S4 }-Containing Polyoxometalate-Based System

Polyoxothiometalate ions (ThioPOM) are active hydrogen-evolution reaction (HER) catalysts based on modular assembly built from electrophilic clusters {MoS_x } and vacant polyoxotungstates. Herein, the dumbbell-like anion [{(PW₁₁ O₃₉ )Mo₃ S₄ (H₂ O)₃ (OH)}₂ ]^8- exhibits very high light-driven HER activity, while the active cores {Mo₃ S₄ } do not contain any exposed disulfido ligands, which were suspected to be the origin of the HER activity. Moreover, in the catalyst architecture, the two central {Mo₃ S₄ } cores are sandwiched by two {PW₁₁ O₃₉ }^7- subunits that act as oxidant-resistant protecting groups and behave as electron-collecting units. A detailed photophysical study was carried out confirming the reductive quenching mechanism of the photosensitizer [Ir(ppy)₂ (dtbbpy)]⁺ by the sacrificial donor triethanolamine (TEOA) and highlighting the very high rate constant of the electron transfer from the reduced photosensitizer to the ThioPOM catalyst. Such results provide new insights into the field of molecular catalytic systems able to promote high HER activity.

The Intrinsic Charge Carrier Behaviors and Applications of Polyoxometalate Clusters Based Materials

Polyoxometalates (POMs) are a series of molecular metal oxide clusters, which span the two domains of solutes and solid metal oxides. The unique characters of POMs in structure, geometry, and adjustable redox properties have attracted widespread attention in functional material synthesis, catalysis, electronic devices, and electrochemical energy storage and conversion. This review is focused on the links between the intrinsic charge carrier behaviors of POMs from a chemistry-oriented view and their recent ground-breaking developments in related areas. First, the advantageous charge transfer behaviors of POMs in molecular-level electronic devices are summarized. Solar-driven, thermal-driven, and electrochemical-driven charge carrier behaviors of POMs in energy generation, conversion and storage systems are also discussed. Finally, present challenges and fundamental insights are discussed as to the advanced design of functional systems based upon POM building blocks for their possible emerging application areas.

Self-Assembled Polyoxometalate Nanodots as Bidirectional Cluster Catalysts for Polysulfide/Sulfide Redox Conversion in Lithium-Sulfur Batteries

Polyoxometalates (POMs) are a class of discrete molecular inorganic metal-oxide clusters with reversible multielectron redox capability. Taking advantage of their redox properties, POMs are thus expected to be directly involved in the lithium-sulfur batteries (Li-S, LSBs) system as a bidirectional molecular catalyst. Herein, we design a three-dimensional porous structure of reduced graphene-carbon nanotube skeleton supported POM catalyst as a high-conductive and high-stability host material. Based on various spectroscopic techniques and in situ electrochemical studies together with computational methods, the catalytic mechanism of POM clusters in Li-S battery was systematically clarified at the molecular level. The constructed POM-based sulfur cathode delivers a reversible capacity 1110 mAh g^-1 at 1.0 C and cycling stability up to 1000 cycles at 3.0 C. Furthermore, Li-S pouch/beaker batteries with a POM-based cathode were successfully demonstrated. This work provides essential inputs to promote molecular catalyst design and its application in LSBs.

A Molecular Hybrid of an Atomically Precise Silver Nanocluster and Polyoxometalates for H2 Cleavage into Protons and Electrons

Atomically precise silver (Ag) nanoclusters are promising materials as catalysts, photocatalysts, and sensors because of their unique structures and mixed-valence states (Ag⁺ /Ag⁰ ). However, their low stability hinders the in-depth study of their intrinsic reactivity and catalytic property accompanying their redox processes. Herein, we demonstrate that a molecular hybrid of an atomically precise {Ag₂₇ }¹⁷⁺ nanocluster and polyoxometalates (POMs) can efficiently cleave H₂ into protons and electrons. The Ag nanocluster accommodates electrons through the redox reaction from {Ag₂₇ }¹⁷⁺ to {Ag₂₇ }¹³⁺ , and the POM ligands play the following important roles: (i) a significant stabilization of the typically unstable Ag nanocluster to preserve its structure during the redox reaction with H₂ , (ii) formation of a unique interface between the Ag nanocluster and metal oxides for efficient H₂ cleavage, and (iii) storage of the generated protons on the negatively charged basic surface.

Multinuclear Lanthanide-Implanted Tetrameric Dawson-Type Phosphotungstates with Switchable Luminescence Behaviors Induced by Fast Photochromism

A series of benzoate-decorated lanthanide (Ln)-containing tetrameric Dawson-type phosphotungstates [N(CH₃)₄]₆H₂₀[{(P₂W₁₇O₆₁)Ln(H₂O)₃Ln(C₆H₅COO)(H₂O)₆]}{[(P₂W₁₇O₆₁)Ln(H₂O)₃}]₂Cl₂·98H₂O [Ln = Sm (1), Eu (2), and Gd (3)] were made using a facile one-step assembly strategy and characterized by several techniques. Notably, the Ln-containing tetrameric Dawson-type polyoxoanions [{(P₂W₁₇O₆₁)Ln(H₂O)₃Ln(C₆H₅COO)(H₂O)₆]}{[(P₂W₁₇O₆₁)Ln(H₂O)₃}]₂^24- are all established by four monolacunary Dawson-type [P₂W₁₇O₆₁]^10- segments, encapsulating a Ln³⁺ ion with two benzoates coordinating to the Ln³⁺ ions. 1-3 exhibit reversible photochromism, which can change from intrinsic white to blue for 6 min upon UV irradiation, and their colors gradually recover for 30 h in the dark. The solid-state photoluminescence spectra of 1 and 2 display characteristic emissions of Ln components based on 4f-4f transitions. Time-resolved emission spectra of 1 and 2 were also measured to authenticate the energy transfer from the phosphotungstate and organic chromophores to Eu³⁺. In particular, 1 shows an effectively switchable luminescence behavior induced by its fast photochromism.

Polyoxometalate-Mediated Vacancy-Engineered Cerium Oxide Nanoparticles Exhibiting Controlled Biological Enzyme-Mimicking Activities

The biological enzyme-mimetic activity of cerium oxide nanoparticles (CeNPs) is well known to scavenge the reactive oxygen and nitrogen species in cell culture and animal models, imparting protection from the deleterious effects of oxidative and nitrosative stress. The superoxide dismutase (SOD)- and catalase-mimicking activity of CeNPs is reported to be controlled by the oxidation state of the surface "Ce" ions, where a high ratio of Ce^3+/4+ or Ce^4+/3+ has been considered for the displayed SOD and catalase-like activity, respectively. However, the redox behavior of CeNPs can be controlled by certain ligands that could offer changes in their enzyme-mimetic properties. Therefore, in this work, we have studied the enzyme-mimetic activities of CeNPs under the influence of polyoxometalates [phosphomolybdic acid (PMA) and phosphotungstic acid (PTA)], which are electron-dense molecules displaying quick and reversible multielectron redox reactions. Results revealed that the interaction of PMA with CeNPs results in the inhibition of the SOD-like activity; however, it has no impact on the catalase-like activity. Contrary to this, the interaction of PTA with CeNPs improved the SOD as well as catalase-like activities of CeNPs (3+), which generally do not exhibit catalase activity in the bare form. Although CeNPs (3+) did not show any peroxidase-like activity, CeNPs (4+) showed excellent activity, which was enhanced after the interaction with polyoxometalates. Further, the autoregeneration ability of CeNPs was found to be intact even after PTA or PMA interaction; however, the full catalytic activity was observed in the case of PTA but partially with PMA.

Influence of the Contact Geometry and Counterions on the Current Flow and Charge Transfer in Polyoxometalate Molecular Junctions: A Density Functional Theory Study

Polyoxometalates (POMs) are promising candidates for molecular electronic applications because (1) they are inorganic molecules, which have better CMOS compatibility compared to organic molecules; (2) they are easily synthesized in a one-pot reaction from metal oxides (MO _x ) (where the metal M can be, e.g., W, V, or Mo, and x is an integer between 4 and 7); (3) POMs can self-assemble to form various shapes and configurations, and thus the chemical synthesis can be tailored for specific device performance; and (4) they are redox-active with multiple states that have a very low voltage switching between polarized states. However, a deep understanding is required if we are to make commercial molecular devices a reality. Simulation and modeling are the most time efficient and cost-effective methods to evaluate a potential device performance. Here, we use density functional theory in combination with nonequilibrium Green's function to study the transport properties of [W₁₈O₅₄(SO₃)₂]^4-, a POM cluster, in a variety of molecular junction configurations. Our calculations reveal that the transport profile not only is linked to the electronic structure of the molecule but also is influenced by contact geometry and presence of ions. More specifically, the contact geometry and the number of bonds between the POM and the electrodes determine the current flow. Hence, strong and reproducible contact between the leads and the molecule is mandatory to establish a reliable fabrication process. Moreover, although often ignored, our simulations show that the charge balancing counterions activate the conductance channels intrinsic to the molecule, leading to a dramatic increase in the computed current at low bias. Therefore, the role of these counterions cannot be ignored when molecular based devices are fabricated. In summary, this work shows that the current transport in POM junctions is determined by not only the contact geometry between the molecule and the electrode but also the presence of ions around the molecule. This significantly impacts the transport properties in such nanoscale molecular electronic devices.

Potentialities of selenium nanoparticles in biomedical science

Selenium nanoparticles (SeNPs) have revolutionized biomedical domain and are still developing rapidly. Hence, this perspective elaborates SeNPs properties, synthesis, and biomedical applications, together with their potential for management of SARS-CoV-2.

Kinetics of the reaction of H2 with Pt0-nanoparticles in aqueous suspensions monitored by the catalytic reduction of PW12O403−

The mechanism of the reaction between Pt⁰ nanoparticles and Hydrogen was measured in the absence of an electric field via following the formation of PW₁₂O₄₀^4−/5−.

36-Nuclearity Organophosphonate-Functionalized Polyoxomolybdates: Synthesis, Characterization and Selective Catalytic Oxidation of Sulfides

The crown-shaped 36-molybdate cluster organophosphonate-functionalized polyoxomolybdates with the highest nuclearity in organophosphonate-based polyoxometalate chemistry, (NH₄ )₁₉ Na₇ H₁₀ [Cu(H₂ O)TeMo₆ O₂₁ {N(CH₂ PO₃ )₃ }]₆ ⋅31 H₂ O, has been reported for the first time. The synthesized 36-molybdate cluster was characterized by routine techniques and tested as a heterogeneous catalyst for selective oxidation of sulfides with impressive catalytic and selective performances after heat treatment. High efficiency (TON=15333) was achieved in the selective oxidation of sulfides to sulfoxides, caused by the synergic effect between copper and polyoxomolybdates and the generation of the cuprous species during the heat treatment.

In-Situ Energy Dispersive X-ray Reflectivity Applied to Polyoxometalate Films: An Approach to Morphology and Interface Stability Issues in Organic Photovoltaics

Organic solar cells, characterized by a symmetrical regular layered structure, are very promising systems for developing green, low cost, and flexible solar energy conversion devices. Despite the efficiencies being appealing (over 17%), the technological transfer is still limited by the low durability. Several processes, in bulk and at interface, are responsible. The quick downgrading of the performance is due to a combination of physical and chemical degradations. These phenomena induce instability and a drop of performance in working conditions. Close monitoring of these processes is mandatory to understand the degradation pathways upon device operation. Here, an unconventional approach based on Energy Dispersive X-ray Reflectivity (ED-XRR) performed in-situ is used to address the role of Wells–Dawson polyoxometalate (K6-P2W18O62, hereafter K6-P2W18) as hole transporting layer in organic photovoltaics. The results demonstrate that K6-P2W18 thin films, showing ideal bulk and interface properties and superior optical/morphological stability upon prolonged illumination, are attractive candidates for the interface of durable OPV devices.

Phosphomolybdic Acid Prevents Nonspecific Nuclear Staining by Picrosirius Red but Is Converted to Molybdenum Blue by Blue Light

Picrosirius red (PSR) staining is generally used to evaluate liver fibrosis; however, PSR sometimes causes nonspecific nuclear staining. In this study, we evaluated the ability of phosphomolybdic acid (PMA) pretreatment to prevent nonspecific nuclear staining by PSR. In a manual evaluation of 27 non-tumor samples from patients with hepatocellular carcinoma, nonspecific nuclear staining was observed in 3.7% of PMA-treated specimens, compared with 85.2% of untreated specimens. Conversely, computer-assisted image analysis (CAIA) identified nonspecific nuclear staining in 0% of PMA-treated samples, vs 44.4% of untreated samples. Surprisingly, after mounting, PMA-treated specimens exhibited a blue tinge because of molybdenum blue (MB) production following sunlight exposure or virtual slide scanning. Using UV cut film, MB production induced by sunlight exposure was prevented; however, the film did not prevent MB production during virtual slide scanning. Moreover, only blue light-emitting diode exposure resulted in a blue tinge in PMA solution. Our data indicated that PMA pretreatment is effective for evaluating liver fibrosis using CAIA. Meanwhile, improvements in virtual slide scanning protocols would directly improve the quality of PMA-pretreated specimens subjected to CAIA.

Sonochemical synthesis of polyoxometalate-stabilized gold nanoparticles for point-of-care determination of acetaminophen levels: preclinical study in an animal model

The aim of this study is the accurate and rapid detection of acetaminophen (AP) for point-of-care (POC) clinical diagnosis. Acetaminophen overdose causes acute liver failure and currently there is a lack of rapid quantitative detection methods for this drug in the emergency room. Here, low-frequency sonication (20 kHz) in the presence of phosphomolybdic acid (PMo₁₂) was used to reduce Au³⁺ to Au⁰ and stabilize the resulting spherical Au⁰ nanoparticles (herein AuNPs). These AuNPs@PMo₁₂ were used as nano-probes for the selective detection of acetaminophen in the presence of other commercial drugs. The optical sensing method we describe is based on the aggregation of AuNPs@PMo₁₂ in the presence of acetaminophen, which produces a red-shift in the absorption spectrum of the AuNPs@PMo₁₂, which is characterised by a color change from red to purple that is visible to the naked eye. Furthermore, the quantitative determination of acetaminophen concentrations can be carried out using the eyedropper function in Microsoft's PowerPoint or open access ImageJ software, using RGB (red, green, and blue) values. To prove the feasibility of this novel nanosensor, the concentration of acetaminophen was measured in over-the-counter pharmaceutical tablets and in serum samples taken from mice. This simple sensing approach offers high stability, selectivity, rapid detection time, and cost saving compared to other detection methods, which therefore opens the way for the development of quantitative POC acetaminophen detection using polyoxometalate-stabilized metal nanoparticles.

The aim of this study is the accurate detection of acetaminophen (AP) for point-of-care (POC) clinical diagnosis. The concentration of acetaminophen was measured in over-the-counter pharmaceutical tablets and in serum samples taken from mice.

Reduced State of the Graphene Oxide@Polyoxometalate Nanocatalyst Achieving High-Efficiency Nitrogen Fixation under Light Driving Conditions

The nitrogen (N₂) reduction to generate ammonia (NH₃) is a prerequisite for inputting fixed nitrogen (N) into a global biogeochemical cycle. Developing highly efficient photocatalysts for N₂ fixation under mild conditions is still a challenge. Herein, we first report three kinds of reduction states of graphene oxide (GO)@polyoxometalate (POM) composite nanomaterials, which have outstanding photocatalytic N₂ fixation activities in pure water without any other electronic sacrificial agents and cocatalysts at atmospheric pressure and room temperature. A lot of experiments show that the remarkable photocatalytic N₂ fixation performance of these three nanocatalysts is due to three factors that doping the reduced POMs (also called heteropoly blues) into the reduce GO (rGO) reduces the aggregation state of rGO (from 5 to 2 nm), resulting in rGO exposing many active sites to enhance the N₂ adsorption amount, these three nanocatalysts possess a wide absorption spectrum and strong reducibility, which facilitate absorb light energy exciting abundant photoelectrons to activate N₂, and rGO can effectively suppress the electrons recombination and rapidly transfer electrons to the absorbed N₂ to accelerate NH₃ production. Among them, r-GO@H₅[PMo₁₀V₂O₄₀] (PMo₁₀V₂) exhibits the highest NH₃ generation efficiency of 130.3 μmol L^-1 h^-1, which is improved by 65.9 and 97.3% compared to the reduced PMo₁₀V₂ (rPMo₁₀V₂) and PMo₁₀V₂. Introduction of POMs provides a new perspective in the design of high-performance photocatalytic N₂ fixation nanomaterials.

Synthesis, X-ray Crystal Structure, and Photochromism of a Sandwich-Type Mono-Aluminum Complex Composed of Two Tri-Lacunary α-Dawson-Type Polyoxotungstates

The synthesis and molecular structure of a dimeric, mono-aluminum complex composed of two tri-lacunary α-Dawson polyoxometalates, [H₁₄Al(B-α-P₂W₁₅O₅₆)₂]^7- (1), is described herein. The tetra-n-butylammonium salt of 1, [(n-C₄H₉)₄N]₇[H₁₄Al(B-α-P₂W₁₅O₅₆)₂] (TBA-1) was prepared by passing an aqueous solution of K₆[B-α-H₃P₂W₁₅O₅₉{Al(OH₂)}₃]⋅14H₂O through an ion-exchange resin column (H⁺-form), followed by addition of tetra-n-butylammonium bromide. Analytically pure and colorless crystals of TBA-1 were obtained via vapor diffusion from acetonitrile/methanol at ~25 °C. Single-crystal X-ray structure analysis revealed that a six-coordinate aluminum ion was sandwiched between two tri-lacunary α-Dawson-type units, resulting in an overall C_2h symmetry. The characterization of TBA-1 was accomplished by elemental analyses, thermogravimetric/differential thermal analyses, Fourier-transform infrared spectroscopy, and solution ³¹P nuclear magnetic resonance spectroscopy. The photochromic properties of TBA-1 were also characterized in methanol under light irradiation (λ = 365 nm and ≥400 nm).

Polyoxometalate-Based Catalysts for CO2 Conversion

Polyoxometalates (POMs) are a diverse class of anionic metal-oxo clusters with intriguing chemical and physical properties. Owing to unrivaled versatility and structural variation, POMs have been extensively utilized for catalysis for a plethora of reactions. In this focused review, the applications of POMs as promising catalysts or co-catalysts for CO₂ conversion, including CO₂ photo/electro reduction and CO₂ as a carbonyl source for the carbonylation process are summarized. A brief perspective on the potentiality in this field is proposed.