PW12 O40 Research Articles

Polyoxometalate Li3 PW12 O40 and Li3 PMo12 O40 Electrolytes for High-energy All-solid-state Lithium Batteries.

Solid-state lithium (Li) batteries promise both high energy density and safety while existing solid-state electrolytes (SSEs) fail to satisfy the rigorous requirements of battery operations. Herein, novel polyoxometalate SSEs, Li3 PW12 O40 and Li3 PMo12 O40 , are synthesized, which exhibit excellent interfacial compatibility with electrodes and chemical stability, overcoming the limitations of conventional SSEs. A high ionic conductivity of 0.89 mS cm-1 and a low activation energy of 0.23 eV are obtained due to the optimized three-dimensional Li+ migration network of Li3 PW12 O40 . Li3 PW12 O40 exhibits a wide window of electrochemical stability that can both accommodate the Li anode and high-voltage cathodes. As a result, all-solid-state Li metal batteries fabricated with Li/Li3 PW12 O40 /LiNi0.5 Co0.2 Mn0.3 O2 display a stable cycling up to 100 cycles with a cutoff voltage of 4.35 V and an areal capacity of more than 4 mAh cm-2 , as well as a cost-competitive SSEs price of $5.68 kg-1 . Moreover, Li3 PMo12 O40 homologous to Li3 PW12 O40 was obtained via isomorphous substitution, which formed a low-resistance interface with Li3 PW12 O40 . Applications of Li3 PW12 O40 and Li3 PMo12 O40 in Li-air batteries further demonstrate that long cycle life (650 cycles) can be achieved. This strategy provides a facile, low-cost strategy to construct efficient and scalable solid polyoxometalate electrolytes for high-energy solid-state Li metal batteries.

Calcined ZnTi-Layered Double Hydroxide Intercalated with H3 PW12 O40 with Efficiently Photocatalytic and Adsorption Performances.

Wastewater treatment is of great significance to environmental remediation. The exploration of efficient and stable methods for wastewater treatment is still a challenging issue. Herein, a heterojunction material with photocatalysis and adsorption properties has been designed to remove the complex pollutants from wastewater. The heterojunction material (ZnO/TiO2 -PW12 , PW12 =[PW12 O40 ]3- ) was synthesized by calcining the ZnTi-layered double hydroxide (ZnTi-LDH) intercalated with the Keggin-type polyoxometalate H3 PW12 O40 . In the construction of ZnO/TiO2 -PW12 it was found that the polyanionic PW12 remained unchanged in the process of forming the proposed heterojunction. The photochemical properties verify that heterojunction synergistic with PW12 facilitated the separation of photoproduced electron-hole pairs and thus suppressed the recombination. Therefore, ZnO/TiO2 -PW12 exhibits excellent photocatalytic property, and the efficiency of Cr(VI) photoreduction reached more than 90 % in the first 3 min. Furthermore, the electrostatic force between the PW12 and cationic dyes makes ZnO/TiO2 -PW12 having an outstanding adsorption performance for cationic dyes, such as rhodamine B, crystal violet and methyl blue. Such heterojunction material combined with polyoxometalate puts forward new insights for the design of functional materials for water treatment with low cost and high efficiency.

Au-Polyoxometalates A-B-A-B Type Copolymer-Analogue Sub-1 nm Nanowires.

Here it is shown that polyoxometalate (POM) clusters (H3 PW12 O40 ·xH2 O, PW12 ) can be introduced to interact with Au nanoclusters to form the "A-B-A-B" type building block ("A" represents Au nanoclusters and "B" stands for PW12 clusters), which continue to grow into copolymer-analogue Au-PW12 sub-1 nm nanowires. Due to the synergetic effect of Au nanoclusters and POMs, the obtained Au-PW12 sub-1 nm nanowires efficiently perform catalytic activity in the photo-electrochemical converting CO2 into CO. Under light, the catalyst maintains remarkable faradic efficiency (FE) of ≈99% from -0.7 to -0.9V (RHE), which is better than that in dark (FE of 66.4-90.64% from -0.7 to -0.9 V (RHE)). Density functional theory calculations and cryo-electron microscope images support the "A-B-A-B" type of structure and mechanistic studies also reveal the higher reactivity toward COOH* formation and CO adsorption on the catalyst, which lead to the superior catalytic activity in CO2 reduction reaction.

Selective Hydrolysis of Terminal Glycosidic Bond in α-1-Acid Glycoprotein Promoted by Keggin and Wells-Dawson Type Heteropolyacids.

The reactivity of a range of Keggin and Wells-Dawson type heteropolyacids (HPAs): H3 PW12 O40 H4 SiW12 O40 , H3 PMo12 O40 , K6 P2 W18 O62 , and NaH2 W12 O4 , towards the heavily glycosylated α-1-acid glycoprotein (AGP) is reported. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) show that after incubation of the protein with HPAs at 80 °C and pH 2.8 complete hydrolysis of terminal glycosidic bond has been achieved, resulting in the removal of sialic acids with no observed destruction of the protein core or the residual glycan chains. The 1 H NMR spectroscopy confirmed that the released sialic acids preserve intact structure upon their excision from the protein, which makes the reported method suitable for the analysis of sialic acid modifications which play an important role in numerous biological processes. The presence of other sugars was not detected by 1 H NMR and HPAEC-PAD, suggesting that HPAs hydrolyze only the terminal glycosidic bond in the glycoprotein, resulting in the selective release of sialic acid from AGP. The kinetic results have shown that under equal temperature and pH conditions, the hydrolysis of the terminal glucosidic bond occurred faster in the presence of HPAs compared to conventional mineral acids. The observed rate constants were in the range 6,7×10-2 -11,9×10-2 min-1 and the complete and selective excision of sialic acids could be achieved within 60 min of incubation. The Trp fluorescence and CD spectroscopy show that non-covalent interaction between HPA and protein takes place in solution which could lead to stabilization of the sialosyl cation that is formed during the glycosidic bond hydrolysis by anionic HPA cluster.

Triblock Copolymer/Polyoxometalate Nanocomposite Electrolytes with Inverse Hexagonal Cylindrical Nanostructures.

The primary issue of polymer electrolytes is to achieve high ion conductivity while retaining mechanical properties. A nanocomposite electrolyte with the inverse hexagonal cylindrical phase (three-dimensionally continuous domains for ion conduction and embedded domains for mechanical support) is prepared through the electrostatic self-assembly of a polyoxometalate (H3 PW12 O40 , PW) and a triblock copolymer poly(N-vinyl pyrrolidone)-block-polystyrene-block-poly(N-vinyl pyrrolidone) (PSP). The cylindrical nanocomposite exhibits a conductivity of 1.32 mS cm-1 and a storage modulus of 4.6 × 107 Pa at room temperature. These two values are higher than those of pristine PSP by two orders of magnitudes and a factor of six, respectively. PW clusters are used as multifunctional nano-additives (morphological inducer, proton conductor, and nano-enhancer) and their incorporation achieves the simultaneous improvement in both conductive and mechanical performance.

ВЗАЄМОДІЯ КОМПЛЕКСНИХ СПОЛУК 1,3,7- ТРИМЕТИЛКСАНТИНІЮ ЗІ АНІОНАМИ ПОЛІОКСОМЕТАЛАТІВ МОЛІБДЕНУ ТА ВОЛЬФРАМУ З ШТУЧНИМИ РАДИКАЛАМИ

In the course of research on interaction of artificial radicals of triphenyl-verdazyl (TPV) and diphenyl picryl hydrazyl (DPPH) with complex compounds of 1,3,7-trimethylxanthine with anions of polyoxometalates of molybdenum and tungsten, an anti-radical action of the coordination compounds mentioned above was proved. During the interaction of these compounds with the TPV-radical, deactivation of the latter occurs. This is evidenced, firstly, by a decrease followed by vanishing of characteristic absorption maximum in the visible area of spectroscopy for the radical form – 720 nm and, secondly, by disappearance on і,Е-curves of maxima of TPV-radical transition into the anionic form. Unequal decrease in absorption maxima of the cationic and anionic forms of TPV can give evidence of complicated nature of the interaction of the TPV-radical with the complex (Hcaf)3[PМе12O40]×6H2O (where Ме = Мо, W). According to the spectroscopy data, compounds (Hcaf)3[PМо12O40]×6H2O showed greater anti-radical action compared to (Hcaf)3[PW 12O40]×6H2O. That is, the antiradical effect of the complex compounds (Hcaf)3[PМо12O40]×6H2O, (Hcaf)3[PW 12O40]×6H2O was proved.

Heightened Integration of POM-based Metal-Organic Frameworks with Functionalized Single-Walled Carbon Nanotubes for Superior Energy Storage.

To increase the conductivity of polyoxometalate-based metal-organic frameworks (POMOFs) and promote their applications in the field of energy storage, herein, a simple approach was employed to improve their overall electrochemical performances by introducing a functionalized single-walled carbon nanotubes (SWNT-COOH). A new POMOF compound, [Cu18 (trz)12 Cl3 (H2 O)2 ][PW12 O40 ] (CuPW), was successfully synthesized, then the size-matched functionalized SWNT-COOH was introduced to fabricate CuPW/SWNT-COOH composite (PMNT-COOH) by employing a simple sonication-driven periodic functionalization strategy. When the PMNT-COOH nanocomposite was used as the anode material for Lithium-ion batteries (LIBs), PMNT-COOH(3) (CuPWNC:SWNT-COOH=3:1) showed superior behavior of energy storage, a high reversible capacity of 885 mA h g-1 up to a cycle life of 170 cycles. The electrochemical results indicate that the uniform packing of SWNT-COOH provided a favored contact between the electrolyte and the electrode, resulting in enhanced specific capacity during lithium insertion/extraction process. This fabrication of PMNT-COOH nanocomposite opens new avenues for the design and synthesis of new generation electrode materials for LIBs.

Tuning Redox Active Polyoxometalates for Efficient Electron-Coupled Proton-Buffer-Mediated Water Splitting.

We present strategies to tune the redox properties of polyoxometalate clusters to enhance the electron‐coupled proton‐buffer‐mediated water splitting process, in which the evolution of hydrogen and oxygen can occur in different forms and is separated in time and space. By substituting the heteroatom template in the Keggin‐type polyoxometalate cluster, H6ZnW12O40, it is possible to double the number of electrons and protonation in the redox reactions (from two to four). This increase can be achieved with better matching of the energy levels as indicated by the redox potentials, compared to the ones of well‐studied H3PW12O40 and H4SiW12O40. This means that H6ZnW12O40 can act as a high‐performance redox mediator in an electrolytic cell for the on‐demand generation of hydrogen with a high decoupling efficiency of 95.5 % and an electrochemical energy efficiency of 83.3 %. Furthermore, the H6ZnW12O40 cluster also exhibits an excellent cycling behaviour and redox reversibility with almost 100 % H2‐mediated capacity retention during 200 cycles and a high coulombic efficiency >92 % each cycle at 30 mA cm−2.

Responsive Janus Cage Reactor.

A Janus silica cage was synthesized by selectively grafting an ionic liquid (IL) and poly-N-isopropylacrylamide (PNIPAM) (lower critical solution temperature (LCST)≈32 °C) onto the exterior and interior sides of the mesoporous SiO2 shell. The paramagnetic core inside the cavity is responsible for magnetic collection. The PW12 O40 3- anion is further conjugated onto the IL side by anion exchange. The Janus cage acts as a thermal-responsive reactor for catalytic oxidization of dibenzothiophene (DBT) in the presence of H2 O2 . The sulfide in the model oil can be completely decomposed at 25 °C, whilst the oxidative products are more dissoluble in water and preferentially captured inside the Janus cage. The Janus cage reactor could be regenerated at high temperature above 32 °C after releasing the products.

Photocatalytic Performance of H6 P2 W18 O62 /TiO2 Nanocomposite Encapsulated into Beta Zeolite under UV Irradiation in the Degradation of Methyl Orange.

In this work, neat and supported H6 P2 W18 O62 into nanocage of β-zeolite were synthesized. However, H6 P2 W18 O62 into nanocage of β-zeolite was synthesized via template synthesis method. In addition, TiO2 was supported on H6 P2 W18 O62 /β zeolite by impregnation method. The obtained materials were characterized by XRD, FT-IR, UV-Vis, FESEM and EDS techniques. Also, W and Ti contents of the catalyst were determined by ICP and EDS technique. The results reveal that the photocatalyst performance depends on catalyst loading, pH effect, and methyl orange concentration. Photocatalytic degradation of methyl orange follows a pseudo-first order kinetic. The chemical oxygen demand (COD) experimental proved mineralization of methyl orange. Another reason for degradation and mineralization of methyl orange is the absence of hydrazine at the end of reaction which is one of the photodecolorization products. The plausible mechanism for photodegradation of MO was proposed.

Synthesis and Characterization of a New Nano Ionic Liquid Based on Dawson-Type Polyoxometalate and Its Application in the Synthesis of Symmetrical N,N′-Alkylidene Bisamides

A new organic-inorganic nano hybrid ionic liquid based on polyoxometalate H2 [MIMBS]4 [P2W18O62]·11 H2O (MIMBS − P2W18), originated from self-assembling of Dawson-type polyoxometalate [P2W18 O62]6− and organic ionic liquid [1-(3-sulfonic group) butyl-3-methyl imidazolium (MIMBS)] components, has been successfully prepared and characterized by elemental analysis, Fourier transform infrared (FT-IR), 1H, 13C, and 15P nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The analysis results present that the size range of the nanosheets are between 40 and 50 nm. The resulting heterogeneous catalyst is shown to be an efficient acidic catalyst for the synthesis of symmetrical N, N′-alkylidene bisamides under solvent-free conditions at 80 °C in high yields. After completion of reaction, the catalyst was simply recovered by filtration and recycled without significant loss in the catalytic activity. The hallmark privileges presented by this method are green chemistry, mild condition, simple method and great yield.

A calibration framework for the determination of accurate collision cross sections of polyanions using polyoxometalate standards.

Polyoxometalates (POMs) are remarkable oxo-clusters forming compact highly charged anions. We measured their collision cross sections (CCS) in N2 with drift tube ion mobility spectrometry (DTIMS). These values were then used to calibrate a traveling wave ion mobility spectrometry (TWIMS) device and the accuracy of the calibration was tested. Six POM standards were analyzed by DTIM-MS (Tofwerk, Thun, Switzerland) at different voltages to determine absolute DT CCS (N2 ) values. Five POM compounds (Lindqvist TBA2 Mo6 O19; decatungstate TBA4 W10 O32; Keggin TBA3 PMo12 O40 ; TBA3 PW12 O40 and Dawson TBA6 P2 W18 O62 ) were used for the calibration of the TWIM-MS instrument (Synapt G2 HDMS, Waters, Manchester, UK) and a sixth Dawson POM, TBA9 P2 Nb3 W15 O62 , was used to compare the accuracy of the calibrations with POM or with polyalanine and dextran reference ions. We determined 45 DT CCS (N2 ) values at 30°C or 60°C. Fourteen DT CCS (N2 ) values at 30°C were used to perform calibration of the TWIMS instrument. Better correlations were observed than when DT CCS values in helium from the literature were used. The accuracy tests on six ions of Dawson POM TBA9 P2 Nb3 W15 O62 led to relative errors below 3.1% while relative errors of 3.6% to 10.1% were observed when calibration was performed with polyalanine and dextran reference ions. Our novel calibration strategy for determination of CCS values of multiply negatively charged ions on TWIM-MS devices based on DT CCS (N2 ) of standard POM structures covered a wider range of CCS and improved the accuracy to 2.1% relative error on average compared with 6.9% using polyalanine and dextran calibration.

A Reversible Redox Reaction in a Keggin Polyoxometalate Crystal Driven by Visible Light: A Programmable Solid-State Photochromic Switch.

The colourless crystals of (PPh4 )3 [PW12 O40 ]⋅3 C3 H7 NO (1) are converted to the dark blue crystals of {(PPh4 )3 [PW12 O40 ]⋅3C3 H7 NO}0.85 {(PPh4 )3 (C3 H7 NO)+. [PWV WVI11 O40 ]- ⋅2C3 H7 NO)}0.15 (2) upon irradiation with visible light in an interesting single crystal to single crystal transformation. This photochromic conversion is accompanied by the reduction of concerned Keggin anion from {PWVI12 } to {PWV WVI11 }. This redox conversion is characterized by various spectroscopic techniques including single crystal X-ray diffraction studies. The photochromic properties of compound 1 can be controlled reversibly through the dimethylformamide (DMF) molecule as a function of temperature and proton exposure in a gas-solid reaction. The present work can be described as a new concept of programmable photochromism with the formation of photochromic pockets in crystalline 1 host (solid state), wherein a solvent can be plugged at a time to show light induced coloration.

A Strategy for Breaking Polyoxometalate-based MOFs To Obtain High Loading Amounts of Nanosized Polyoxometalate Clusters to Improve the Performance of Dye-sensitized Solar Cells.

Polyoxometalates (POM) have already been confirmed to act as effective electron-transfer mediators for improving the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) based on previous studies. However, the improvement may be limited by the agglomeration of the polyoxoanions. In this paper, the previous synthesis strategy is improved upon by breaking the metal-organic frameworks (MOFs) with POMs as the secondary building units ([Ni(bpp)(H2 O)2 ]3 [P2 W18 O62 ]⋅24 H2 O (1) (bpp=1,3-bis(4-pyridyl)propane) and H6 [Cu3 (H2 O)6 (P2 W18 O62 )2 (3-dpye)6 ]⋅28 H2 O (2) (3-dpye=N,N'-bis(3-pyridinecarboxamide)-1,2-ethane)) to design and synthesize small sized and highly disperse POM nanoparticles by means of compositing with TiO2 , through calcination to remove the organic ligand. TEM and element mapping confirm that P2 W18 O626- (denoted as P2 W18 ) nanoparticles with the diameter of ≈1 nm are uniformly distributed in TiO2 composites. The loading amount (wt. %) of POM in MOFs reaches 75.67 %. The small sized and highly disperse P2 W18 nanoparticles may provide more active sites and specific surface areas for improving the PCE of DSSCs. Finally, the investigations indicate that the PCE of composite P2 W18 ⋅NiO@TiO2 photoanodes is up to 7.56 %, which was 26 % higher than the pristine TiO2 based photoanodes.

Synthesis of Butyl Levulinate Based on α-Angelica Lactone in the Presence of Easily Separable Heteropoly Acid Catalysts.

A series of choline (Ch)-exchanged heteropoly acids (HOCH2 CH2 N(CH3 )3 )x H(6-x) P2 W18 O62 [abbreviated as Chx H(6-x) P2 W18 O62 , x=1-6] was synthesized and used as catalysts for the reaction of α-angelica lactone (alpha-AL) with n-butanol to form butyl levulinate (BL). The solubility of Chx H(6-x) P2 W18 O62 in the reaction mixture was temperature dependent: The catalysts were soluble under the reaction conditions and precipitated upon cooling of the reaction mixture. This facilitated recovery of the catalysts from the liquid phase. Importantly, an increase of the Ch content caused a decrease of the catalyst solubility. Catalytic activity of Chx H(6-x) P2 W18 O62 for the reaction with n-butanol appeared to be in good agreement with the concentration of Brønsted-acidic sites. The results suggest that the reaction proceeded through formation of pseudo-butyl levulinate as intermediate. Ch2 H4 P2 W18 O62 exhibited the best balance between catalytic activity and temperature-dependent solubility. The yield of BL reached 79.4 % at full conversion of alpha-AL at a moderate temperature of 75 °C in an open system. Chx H(6-x) P2 W18 O62 could be successfully reused five times without significant loss of activity.

Functionalization of Polypyrrole Nanopipes with Redox-Active Polyoxometalates for High Energy Density Supercapacitors.

Hybrid materials are very attractive for the fabrication of high-performance supercapacitors. Here, we have explored organic-inorganic hybrid materials based on open-end porous 1 D polypyrrole nanopipes (PPy-NPipes) and heteropolyoxometalates (phosphotungstate ([PW12 O40 ]3- , PW12 ) or phosphomolybdate ([PMo12 O40 ]3- , PMo12 )) that display excellent areal capacitances. Two different hybrid materials (PMo12 @PPy and PW12 @PPy) were effectively synthesized and used for symmetric supercapacitors. The anchoring of the inorganic nanoclusters onto the conducting polymer nanopipes led to electrodes that stood up to our best expectations exhibiting outstanding areal capacitances that are almost 1.5 to 2 fold higher than that of pristine PPy-NPipes. In addition, symmetric cells based on PMo12 @PPy and PW12 @PPy hybrid electrodes were fabricated and showed significant improvement in cell performance with very high volumetric capacitances in the range of 6.3-6.8 F cm-3 (considering the volume of whole device). Indeed, they provide extended potential windows in acidic electrolytes (up to 1.5 V) which led to ultrahigh energy densities of 1.5 and 2.2 mWh cm-3 for PMo12 @PPy and PW12 @PPy cells, respectively. Thus, these unique organic-inorganic hybrid symmetric cells displayed extraordinary electrochemical performances far exceeding those of more complex asymmetric systems.

Catalytic Conversion of Carbohydrates to Levulinate Ester over Heteropolyanion-Based Ionic Liquids.

An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS]3 PW12 O40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control.

Biological evaluation of two Keggin-type polyoxometalates containing glycine as mushroom tyrosinase inhibitors.

Two Keggin-type polyoxometalates (POMs) containing glycine, (HGly)3 PW12 O40 and (HGly)4 SiW12 O40 , were synthesized and evaluated as mushroom tyrosinase inhibitors. The spectrophotometric method results showed that both (HGly)3 PW12 O40 and (HGly)4 SiW12 O40 could strongly inhibit the diphenolase activity of the tyrosinase and that their inhibition mechanisms were reversible. Their half-inhibition concentration values were estimated to be 1.55 and 1.39mmol/L, respectively. The inhibition kinetics analysis by Lineweaver-Burk plots indicated that (HGly)3 PW12 O40 was an uncompetitive inhibitor with KIS =0.046mmol/L, whereas (HGly)4 SiW12 O40 was a noncompetitive inhibitor with KI =KIS =2.17mmol/L. This study may help to extend the application of POMs in the fields of medicine and food preservation.

Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions.

The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12 O40 ](3-) (PW12 ) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73 Al0.22 (OH)2 [PW12 O40 ]0.04 ⋅0.98 H2 O (Mg3 Al-PW12 ) has been successfully obtained by applying a spontaneous flocculation method. The Mg3 Al-PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3 Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3 Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2 -Z' type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2-propanol :Vwater =2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3 Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3 Al-PW12 -catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction.

Direct Synthesis of Controlled-Size Nanospheres inside Nanocavities of Self-Organized Photopolymerizing Soft Oxometalates [PW12 O40 ]n (n=1100-7500).

The unusual self-assembly of {(BMIm)2 (DMIm)[PW12 O40 ]}n (n=1100-7500) (BMIm=1-butyl-3-methylimidazolium, DMIm=3,3'-dimethyl-1,1'-diimidazolium) soft oxometalates (SOMs) with controlled size and a hollow nanocavity was exploited for the photochemical synthesis of polymeric nanospheres within the nanocavity of the SOM. The SOM vesicle has been characterized by using several techniques, including dynamic light scattering (DLS), static light scattering (SLS), attenuated total reflection (ATR) IR spectroscopy, Raman spectroscopy, microscopy, and zeta-potential analysis. The self-assembly and stabilization of this soft-oxometalate vesicle has been shown by means of counter-ion condensation. The immediate implication of such stabilization-the variation of the dielectric constant with the hydrodynamic radius of the vesicle-has been used to synthesize vesicles of controlled size. Such vesicles of varying size have been used as templates for polymerization reactions that produce polymeric spheres of controlled size. Direct evidence shows that the SOM behaves as a model heterogeneous catalytic system. Such surfactant- and initiator-free photochemical synthetic routes for obtaining uniform latex spheres could be used in the making of optical bandgap materials, inverse opals, and paints.