Structural and Luminescence Properties of Silica-Based Hybrids Containing New Silylated-Diketonato Europium(III) Complex

A new betadiketonate ligand displaying a trimethoxysilyl group as grafting function and a diketone moiety as complexing site (TTA-Si = 4,4,4-trifluoro-2-(3-trimethoxysilyl)propyl)-1-3-butanedione (C4H3S)COCH[(CH2)3Si(OCH3)3]COCF3) and its highly luminescent europium(III) complex [Eu(TTA-Si)3] have been synthesized and fully characterized. Luminescent silica-based hybrids have been prepared as well with this new complex grafted on the surface of dense silica nanoparticles (28 (+/-3 nm) or on mesoporous silica particles. The covalent bonding of Eu(TTA-Si)3 inside the core of uniform silica nanoparticles (40 (+/- 5 nm) was also achieved. Luminescence properties are discussed in relation to the europium chemical environment involved in each of the three hybrids. The general methodology proposed allowed high grafting ratios and overcame chelate release and tendency to agglomeration, and it could be applied to any silica matrix (in the core or at the surface, nanosized or not, dense or mesoporous) and therefore numerous applications such as luminescent markers and luminophors could be foreseen

Organosilylated complex [Eu(TTA)₃(Bpy-Si)]: a bifunctional moiety for the engeneering of luminescent silica-based nanoparticles for bioimaging

A new highly luminescent europium complex with the formula [Eu(TTA)₃(Bpy-Si)], where TTA stands for the thenoyltrifluoroacetone, (C₄H3S)COCH₂COCF₃, chelating ligand and Bpy-Si, Bpy-CH₂NH(CH₂)₃(OEt)₃, is an organosilyldipyridine ligand displaying a triethoxysilyl group as a grafting function has been synthesized and fully characterized. This bifunctional complex has been grafted onto the surface of dense silica nanoparticles (NPs) and on mesoporous silica microparticles as well. The covalent bonding of [Eu(TTA)₃(Bpy-Si)] inside uniform Stöber silica nanoparticles was also achieved. The general methodology proposed could be applied to any silica matrix, allowed high grafting ratios that overcome chelate release and the tendency to agglomerate. Luminescent silica-based nanoparticles SiO₂-[Eu(TTA)₃(Bpy-Si)], with a diameter of 28 ± 2 nm, were successfully tested as a luminescent labels for the imaging of Pseudomonas aeruginosa biofilms. They were also functionalized by a specific monoclonal antibody and subsequently employed for the selective imaging of Escherichia coli bacteria

Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu3+-Doped Mixed Rare Earth Nano-Orthophosphates

Eu3+-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd) have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For LaxY1–xPO4: Eu3+, the ion radius distinction between the La3+ and Y3+ is so large that only La0.9Y0.1PO4: Eu3+ shows the pure monoclinic phase. For LaxGd1–xPO4: Eu3+ system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, YxGd1–xPO4: Eu3+, Y0.1Gd0.9PO4: Eu3+ and Y0.5Gd0.5PO4: Eu3+ samples present the pure hexagonal phase and nanorods microstructure, while Y0.9Gd0.1PO4: Eu3+ exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu3+ in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure)

Functionalized Mesoporous SBA-15 with CeF3: Eu3+ Nanoparticle by Three Different Methods: Synthesis, Characterization, and Photoluminescence

Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF3: Eu3+ phosphor layer on its surface (denoted as CeF3: Eu3+/SBA-15/IS, CeF3: Eu3+/SBA-15/SI and CeF3: Eu3+/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF3: Eu3+ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce3+ and the central Eu3+ ion. They show the characteristic emission of Ce3+ 5d → 4f (200–320 nm) and Eu3+5D0 → 7FJ(J = 1–4, with 5D0 → 7F1 orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF3: Eu3+/SBA-15/SS exhibits the characteristic emission of Eu3+ ion under UV irradiation with higher luminescence intensity than the other materials

ÉTUDE PAR MICROSCOPIE ÉLECTRONIQUE ET SPECTROSCOPIE OPTIQUE DU SYSTÈME ZrO2/Y2O3 : Eu

Les techniques conjuguées de la diffraction des rayons X, de la diffraction électronique et de la spectroscopie optique ont été appliquées à l'étude du système ZrO2/Y2O3. Dans l'intervalle 90 ZrO2/10 YO1,5—C-Y2O3 aucune phase ordonnée n'a été décelée par les techniques de diffraction. La spectroscopie optique révèle une tendance à l'ordre à courte distance ou peut-être seulement l'existence d'une coordination préférentielle des cations dictée par la composition.X-Ray diffraction, electronic diffraction and optical spectroscopy techniques have been applied to the study of the ZrO2/Y2O3 system. Diffraction techniques did not reveal any ordered compound in the range 90 ZrO2/10 YO1,5—C-Y2O3. By optical spectroscopy, one might suspect some very short range ordering or perhaps the existence of a preferred coordination polyhedron, for cations, assigned by composition

Structural studies in lead germanate glasses: EXAFS and vibrational spectroscopy

The Raman, IR absorption and EXAFS spectra at the Ge K-edge and Pb LIII-edge of eight lead germanate glasses, with general formula xPbO(1-x)GeO2 with x = 0.20, 0.25, 0.33, 0.40, 0.50, 0.53, 0.56 and 0.60, have been measured. The occurrence of [GeO6] units besides [GeO4] could not be deduced unambiguously from the data. The vibrational and EXAFS data agree with a progressive depolymerization of the network. Starting from all Ge atoms linked to four bridging oxygens in GeO2 (x = 0), the number of tetrahedral units with one or two non-bridging oxygens increases with x. At low content, Pb2+ ions act as modifiers in the germanate structure, but to a lesser extent than an equivalent number of alkaline ions. © 1993

Luminescent Terbium Doped Aluminate Particles: Properties and Surface Modification with Asparagine

New luminescent organic-inorganic hybrid particles based on Tb-doped aluminates and asparagine (Asn) surface modifiers were investigated. The Tb 3+ doped inorganic core was obtained by spray pyrolysis, at 200 °C γ-AlOOH (BOE:Tbx%) or at 700 °C γ-Al 2 O 3 (γTA:Tbx%). The reaction of Asn with boehmite in water disaggregated the sub-micronic boehmite particles to give stable dispersion of surface modified nanoparticles Asn:BOE:Tbx% (x = 1 or 5). Concerning the Asn:γTA:Tbx% system, an Asn film wrapping alumina particles was observed. Photoluminescence spectra exhibited the bands assigned to Tb 3+ 5 D 4 → 7 F J = 6-3 transitions. A broad absorption band (240 nm) was assigned to the host (aluminate) to ion (Tb 3+ ) energy transfer. Efficient energy transfer was observed when active ions are incorporated in the defect-spinel structure of γTA, whereas it was relatively weak for BOE:Tb where Tb 3+ are bonded to the hydroxyls groups at nanocrystals surface. It is noticeable that Asn strengthens the linkage of Tb 3+ with the aluminate matrix, enhancing the host to dopant energy transfer