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Water-soluble titanium-oxides: Complexes, clusters and nanocrystals
摘要： The water-soluble titanium-oxide structures covered in this review span a continuum from molecular clusters to colloidal nanocrystals. Here, a deliberate distinction is made between titanium clusters and nanoparticles with organic ligands, soluble in organic solvents, and related structures prepared and soluble in water. This distinction is made in response to rapid developments in three areas covered in this article: small titanium-oxide clusters prepared at low pH values in water, heterpolytungstate macroanions with high-nuclearity titanium-oxide cores, and polyoxometalate complexes of anatase-phase TiO2. The latter nanostructures occupy a unique position between polyoxometalate macroanions and traditional colloidal TiO2. As such, the progressively larger water-soluble titanium-oxide structures covered in the three main sections of this review establish a continuum that begins to blur the longstanding divide between molecular and colloid science.
关键词： Polyoxometalates,Titanium oxide,Water soluble,Clusters,Nanocrystals
更新于2025-09-23 15:23:52
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Coordination Polymers Based on Organic–Inorganic Hybrid Rigid Rod Comprising a Backbone of Anderson-Evans POMs
摘要： To construct polyoxometalates coordination polymers (PCPs), we prepared two pyridine ligand functionalized Anderson POMs: (TBA)3[MnMo6O18((OCH2)3CN=CH-4-Py)2]·DMF ((TBA)3POM-1, TBA = tetrabutyl ammonium, Py = pyridine) and (TBA)3[MnMo6O18((OCH2)3CN=CH-3-Py)2] ((TBA)3POM-2) via the post-functionalization of (TBA)3[MnMo6O18((OCH2)3CNH2)2] (Anderson-NH2) by 4-pyridinealdehyde and 3-pyridinealdehyde, respectively. They are characterized using X-ray single crystal diffraction, MALDI-TOF MS, ESI MS, FT-IR, UV-Vis and 1H NMR . The self-assembly of (TBA)3POM-1 and [Cu(PPh3)2(CH3CN)2]ClO4 (CuP2) in the mole ratios of 1 : 2 and 1 : 3, both gave the same 1D double chain with the molecular formula of (NBu4)n{[Cu(PPh3)2]2(POM-1)}n (7.5DMF)n (1). On the contrary, the self-assembly of (TBA)3POM-2 and CuP2 in the mole ratio of 1:2 yields a 2D coordination polymer of (TBA)n{[Cu(PPh3)2]2(POM-2)}n·(2DMF)n (2), while that self-assembly process in the mole ratio of 1:3 results in different 2D coordination polymer of {[Cu(PPh3)2]3(POM-2)·(CH3CN)}n·(5CH3CN)n (3). Compounds 1-3 can keep their skeleton structures below 230oC. They exhibit intense green emission (496nm for 1; 537nm for 2; 530nm for 3) by ultra-violet irradiation (327nm for 1; 303nm for 2; 331nm for 3), which can be tentatively ascribed as ILCT with metal perturbation.
关键词： Luminescence,Polyoxometalates,Pyridine,Coordination Polymer,Copper (I)
更新于2025-09-23 15:23:52
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A series of germanotungstate-based 3d-4f heterometallic compounds with visible-light induced photocatalytic, electrochemical and magnetic properties
摘要： A series of 3d-4f heterometallic germanotungstate dimers {[Cu(dap)(H2O)3][LnCu3(dap)3(OH)3(H2O)2(GeW11O39)]}·nH2O (Ln = SmⅢ, n = 11 (1), EuⅢ, n = 12 (2), GdⅢ, n = 10 (3) and TbⅢ, n = 13 (4); dap = 1, 2-diaminopropane) have been prepared under hydrothermal conditions and structurally characterized by IR, UV-Vis, XRD, and X-ray single-crystal diffraction. Compounds 1–4 are essentially isomorphic and display organic-inorganic hybrid dimeric structures consisting of [LnCu3(dap)3(OH)3(H2O)(GeW11O39)]2 4– with two supporting [Cu(dap)(H2O)3]2+ cations on both sides. The four compounds all exhibit the excellent photocatalytic activities to delaradation of methylene blue (MB) and rhodamine-B (RhB) under visible light irradiation in the presence of H2O2. Additionally, 1–4 displays an apparent electrocatalytic activity for the reduction of hydrogen peroxide. The variable-temperature magnetic studies show that the magnetic behaviours of 1, 2 and 4 are dominated by antiferromagnetic coupling interactions, while that of 3 is ferromagnetic interactions coexist along with antiferromagnetic interactions.
关键词： Photocatalytic properties,Lacunary polyoxometalates,magnetic properties,Crystal structure,Electrocatalytic properties,3d-4f Heterometallic compounds
更新于2025-09-23 15:23:52
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In situ electrochemical reduction assisted assembly of a graphene-gold nanoparticles@polyoxometalate nanocomposite film and its high response current for detection of hydrogen peroxide
摘要： The nanocomposite film including polyoxometalate (POM) cluster K28Li5H7P8W48O184·92H2O (P8W48), reduced graphene oxide (rGO) and Au nanoparticles (Au NPs) was successfully fabricated by electrochemical reduction assisted technique. This synthesis was novel, convenient, and environmentally friendly. Moreover, the time of fabricating process was greatly shorten to about 1 hour comparing to that of the traditional method of layer by layer (LbL) self-assembly. The reduced P8W48 was served as reducing agent, stabilizer and bridging molecules simultaneously in the composite film. The structure of the composite material was verified by comprehensive characterization using scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The investigation of the electrocatalysis for H2O2 showed that the {PEI/rGO}-Au@P8W48 modified electrode has high catalytic activity, good sensitivity, good selectivity, low detection limit and fast response. In addition, the result indicated that the electrocatalytic activity of the electrode with Au NPs was better than that of the electrode without Au NPs. The enhanced catalytic property was attributed to the synergistic effect of the rGO, P8W48 and Au NPs.
关键词： graphene,hydrogen peroxide,Au nanoparticles,electrocatalysis,polyoxometalates
更新于2025-09-23 15:22:29
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Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals
摘要： Intraband and plasmonic transitions have appeared over the last years as an interesting tool to achieve optical absorption in the mid infrared. Tuning the doping magnitude has become a major challenge not only to tune the optical spectrum but also properties such as the dark current or the time response. Here we investigate the case of self-doped HgSe colloidal quantum dots (CQDs). Tuning of the doping was so far relying on band bending induced by a dipole design at the nanoparticle surface. With such a surface gating approach, it is difficult to conciliate both the massive tuning of the Fermi level with the preservation of transport properties of the CQD arrays. Here we propose a strategy to graft functionalized polyoxometalates (POMs) at the CQD surface and obtain simultaneously a massive tuning of the carrier density (≈5 electrons per nanoparticle) and conduction properties. We bring a consistent demonstration of the HgSe CQD doping decrease by a charge transfer to the POM. This method is highly promising for large tuning of carrier density in degenerately doped semiconductor nanoparticles.
关键词： Intraband,mid infrared,charge transfer,polyoxometalates,plasmonic transitions,doping control,HgSe colloidal quantum dots
更新于2025-09-23 15:21:21
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Self-Assembly of Europium-Containing Polyoxometalates/Tetra- <i>n</i> -alkyl Ammonium with Enhanced Emission for Cu <sup>2+</sup> Detection
摘要： Lanthanide-containing polyoxometalates (POMs) can be used to detect various materials, but their luminescence in water has suffered enormous limitations due to the strong fluorescence quenching. Herein, to resolve this problem, three-dimensional nanoparticles built by mixed Weakley-type europium-containing POMs (Na9[EuW10O36]·32H2O, abbreviated to EuW10) and tetra-n-alkyl ammonium (TA) with enhanced fluorescent properties have been designed in aqueous solution using an ionic self-assembly (ISA) technique, which is mainly driven by the electrostatic interaction between EuW10 and TA. The morphology and fluorescent properties of the system as well as some influencing factors (alkyl chain length, amino group, and inorganic salt concentration) were systematically investigated. The results indicated that the fluorescent intensity of EuW10/tetramethylammonium bromide (TMAB) composite increased about 14 times, whereas the extent of increase of fluorescence for EuW10/tetraethylammonium bromide (TEAB) and EuW10/tetrabutylammonium bromide (TMAB) composites gradually decrease due to the bulkier steric hindrance of the longer alkyl chain. Besides, the luminescence of EuW10/TMAB nanoparticles is pH responsive, and the reversibility of their structures and luminescence can be realized upon the addition of NaOH/HCl. Moreover, the EuW10/TMAB system also shows great fluorescence-sensing behavior, which could detect Cu2+ with a detection limit of 0.15 μM. Our work provides a facile construction strategy for a functional fluorescent complex via POMs-based supramolecular self-assembly in aqueous solution, which will be further used in biomarkers and sensors.
关键词： Cu2+ detection,fluorescence enhancement,ionic self-assembly,lanthanide-containing polyoxometalates,pH-responsive
更新于2025-09-23 15:21:01
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Design of an inherently-stable water oxidation catalyst
摘要： While molecular water-oxidation catalysts are remarkably rapid, oxidative and hydrolytic processes in water can convert their active transition metals to colloidal metal oxides or hydroxides that, while quite reactive, are insoluble or susceptible to precipitation. In response, we propose using oxidatively-inert ligands to harness the metal oxides themselves. This approach is demonstrated by covalently attaching entirely inorganic oxo-donor ligands (polyoxometalates) to 3-nm hematite cores, giving soluble anionic structures, highly resistant to aggregation, yet thermodynamically stable to oxidation and hydrolysis. Using orthoperiodate (at pH 8), and no added photosensitizers, the hematite-core complex catalyzes visible-light driven water oxidation for seven days (7600 turnovers) with no decrease in activity, far exceeding the documented lifetimes of molecular catalysts under turnover conditions in water. As such, a fundamental limitation of molecular complexes is entirely bypassed by using coordination chemistry to harness a transition-metal oxide as the reactive center of an inherently stable, homogeneous water-oxidation catalyst.
关键词： visible-light driven,hematite,polyoxometalates,water oxidation,catalyst
更新于2025-09-23 15:21:01
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Ionic Self-Assembled Luminescent Nanospheres from Cationic Polyelectrolyte and Eu-Containing Polyoxometalate
摘要： Using the ionic self-assembly (ISA) strategy to combine Eu-containing polyoxometalates (Eu-POMs) and organic molecules mainly through noncovalent electrostatic interactions can protect Eu-POMs from solvent quenching of luminescence and enhance their processability. For this reason, a cationic polyelectrolyte, branched polyethyleneimine (PEI), and a Eu-POM, Na9(EuW10O36)·32H2O (EuW10), were used here to construct luminescence-enhanced spherical aggregates with diameters ranging from 50 to 200 nm. At a fixed concentration of EuW10, the phase behavior and luminescence properties of the mixture could be modulated by the PEI concentration. Such ISA-induced aggregates could effectively shield water molecules and result in better photophysical properties. Compared to bare EuW10, the absolute quantum yield and lifetime of luminescence for aggregates increased 10 and 5 times, respectively. Meanwhile, the sensitivity of the EuW10 coordination structure to the environment made it possible for obtained aggregates being used to detect either copper cations or permanganate anions due to their strong specific quenching effects to luminescence. Such a new type of luminescent soft material not only provided a reference for exploring the luminescence enhancement mechanism of lanthanide through self-assembly in aqueous solution but also exhibited potential in detection by luminescence analysis.
关键词： polyoxometalates,permanganate detection,polyethyleneimine,ionic self-assembly,copper detection,luminescence enhancement,luminescent nanospheres
更新于2025-09-23 15:19:57
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Shape-control of CeF <sub/>3</sub> nanocrystals by doping polyoxometalates: syntheses, characterization and tunable photoluminescence
摘要： A series of CeF3 nanocrystals with uniform morphologies have been synthesized by introducing various polyoxometalates as dopants and shape modifiers. The results indicate that the shape and photoluminescence of the CeF3 nanocrystals could be finely tuned by changing the component and amount of the polyoxometalates.
关键词： doping,CeF3 nanocrystals,photoluminescence,shape-control,polyoxometalates
更新于2025-09-19 17:15:36
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A solid-state supramolecular hybrid complex based on dimethylammonium ions and silicon molybdate: Crystal structure, photochromic properties and catalytic performance
摘要： A novel organic-inorganic hybrid supramolecular Complex (C2H8N)4SiMo12O40 based on Keggin building blocks has been successfully synthesized by solvothermal method. Single-crystal X-ray analysis revealed that it crystallized in orthorhombic system, Pnma space group. The supramolecular crystalline network is formed via intermolecular hydrogen bonds. The target product was characterized by Infrared spectrum, thermogravimetric-differential thermal, cyclic voltammetry and fluorescent spectrum. Results prove that Complex emits blue fluorescence and has irreversible photochromic properties. Differential thermal-thermogravimetric and cyclic voltammetry shows that Complex has high thermal stability and strong oxidizability. The catalytic performances of Complex were investigated by solid-gas heterogeneous catalysis method. Using solid target product as catalyst, the catalyze degradation of methanol was tested in the temperature range from rt. to 160 °C. When the system flow rate is 5.0 mL min?1, initial concentration of methanol is 5.34 g m?3, reaction temperature is 150 °C, eliminating rate of methanol is 76%, those indicate that Complex has good catalytic activity.
关键词： Keggin structure,Polyoxometalates,Catalytic elimination,Methanol,Organic-inorganic hybrid
更新于2025-09-19 17:15:36