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The aquasoluble FeIII complexes [Fe(H2O)3(L1)] ⋅ 4H2O (Fe1) and [Fe(H2O)3(L2)] ⋅ 3H2O (Fe2), bearing the basic forms of 5‐chloro‐3‐(2‐(4,4‐dimethyl‐2,6‐dioxocyclohexylidene)hydrazinyl)‐2‐hydroxy‐benzenesulfonic acid (H3L1) and 3‐(2‐(2,4‐dioxopentan‐3‐ylidene)hydrazinyl)‐2‐hydroxy‐5‐nitrobenzenesulfonic acid (H3L2), were incorporated for the first time into amine‐functionalized SBA‐15 support via an impregnation method. The successful preparation of the composites was confirmed by Fourier‐Transform Infrared spectroscopy (FT‐IR), powder X‐ray diffraction (XRD), scanning electron microscope (SEM/EDS), transmission electron microscopy (TEM), elemental analysis, and nitrogen adsorption‐desorption isotherms. The resulting Fe1@aptesSBA‐15 and Fe2@aptesSBA‐15 composites were tested as the first SBA‐15‐based heterogeneous catalysts for the conversion of furfuryl alcohol under mild reaction conditions (80 to 100 °C) and with an environmentally friendly oxidant (TBHP, 70 % aq. sol. with 1 : 1 oxidant/substrate molar ratio). The influence of various factors, such as reaction time, amounts of oxidant and catalyst, was investigated. The reaction time can be fairly reduced by adopting a microwave‐assisted method allowing it to reach complete conversion after 0.25 h, in the absence of any added solvent or additive. Under these conditions, a vigorous furfuryl alcohol polymerization process occurred, with furfural as a by‐product. Recycling studies were carried out for Fe2@aptesSBA‐15 and after four consecutive runs, the overall conversion of furfuryl alcohol remained high (≥99 %), without an appreciable change in the obtained yield. [ABSTRACT FROM AUTHOR]

The NMR relaxivities of the decatungstolanthanoate core‐shell nanoparticles, prepared by encapsulating [Ln(W5O18)2]9− polyoxometalates (LnPOM) within amorphous silica shells (K9[Ln(W5O18)2]@SiO2), were studied along the Ln series. The relaxivity of GdPOM is slightly higher than for Gd‐DTPA due to second‐sphere relaxation effects, but the values for the other paramagnetic LnPOMs are much smaller due to the short T1e values of their Ln3+‐ions. The NPs have core‐shell spherical structures, with LnPOM‐containing cores with 9.5–28 nm diameters, and 4.0–11.0 nm thick amorphous silica shells. In water suspensions, the NPs have negative zeta potentials (−32.5 to −40.0 mV) and time‐dependent hydrodynamic diameters (31–195 nm) reflecting the formation of aggregates. The relaxivities of GdPOM@SiO2 NPs suspensions (r1=10.97 (mM Gd)−1 s−1, r2=12.02 (mM Gd)−1 s−1, 0.47 T, 25 °C) are considerably larger than for the GdPOM solutions, indicating that their silica shell is significantly porous to water. This increase is limited by the agglomeration of the complexes in the NPs core, limiting their access to water to those at the core surface. Replacing half of the Gd3+ ions by Eu3+ decreases the NPs r1 and r2 relaxivities at 0.47 T to 20 % and 35 % of their initial values, which are still considerable, but does not affect the efficient luminescence properties of the Eu3+ centers. This indicates that the mixed NPs have potential as dual modality MRI/optical imaging contrast agents. [ABSTRACT FROM AUTHOR]

The incorporation of europium polyoxometalates into silica nanoparticles can lead to a biocompatible nanomaterial with luminescent properties suitable for applications in biosensors, biological probes, and imaging. Keggin-type europium polyoxometalates Eu(PW11) x ( x = 1 and 2) with different europium coordination environments were prepared by using simple methodologies and no expensive reactants. These luminescent compounds were then encapsulated into silica nanoparticles for the first time through the water-in-oil microemulsion methodology with a nonionic surfactant. The europium polyoxometalates and the nanoparticles were characterized by using several techniques [FTIR, FT-Raman, 31P magic angle spinning (MAS) NMR, and TEM/energy-dispersive X-ray spectroscopy (TEM-EDS), AFM, dynamic light scattering (DLS), and inductively coupled plasma MS (ICP-MS) analysis]. The stability of the material and the integrity of the europium compounds incorporated were also examined. Furthermore, the photoluminescence properties of the Eu(PW11) x@SiO2 nanomaterials were evaluated and compared with those of the free europium polyoxometalates. The silica surface of the most stable nanoparticles was successfully functionalized with appropriate organosilanes to enable the covalent binding of oligonucleotides. [ABSTRACT FROM AUTHOR]

A series of polysaccharide-based transparent composite films containing lanthanopolyoxometalates (LnPOMs) have been prepared by using a water-soluble cationic chitosan derivative [HTCC = N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride] and pullulan (PUL). HTCC was more suitable than pure chitosan for this purpose due to its positive charge and solubility in water over a broad range of pH values. The LnPOMs [Ln(W5O18)2]9- (Ln = Eu and Tb) were incorporated into the polysaccharides. EuPOMs encapsulated in amorphous silica shells were also incorporated into the polysaccharides to test the effect on film processing of the loading of nanoparticles instead of LnPOM anions. The incorporation of LnPOMs or LnPOM/silica core/shell nanoparticles into either HTCC or PUL polysaccharides originated clear transparent films. These composite films are transparent in daylight and exhibit visible emission under UV excitation. Photoluminescence studies (emission and excitation spectra and emission decay curves) were performed on the newly prepared films. [ABSTRACT FROM AUTHOR]

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