Β-diketone Chelates Research Articles

Real-Time Tracking of Highly Luminescent Mesoporous Silica Particles Modified with Europium β-Diketone Chelates in Living Cells.

Highly luminescent europium complexes modified mesoporous silica particles (MSP) were synthesized as an imaging probes for both in-vitro diagnostic and in-vivo cellular tracking agents. Europium β-diketone chelates (4,4,4-trifluoro-l-(2-thienyl)-l,3-butanedione) trioctylphosphine europium (III) (Eu(TTA)3(P(Oct)3)3) were incorporated inside the nanocavities that existed in hierarchical MSP (Eu@MSP). The MSP and Eu@MSP on mouse bone marrow-derived macrophages (BMDMs) did not show any toxic effect. The MSP and Eu@MSP in the BMDMs were found at cytoplasm without any degradation and immunogenicity. However, both pro- and anti-inflammatory cytokines of macrophages were significantly increased when lipopolysaccharide and a high concentration (100 μg/mL) of MSP and Eu@MSP were treated simultaneously.

Luminescent sensor based on the lanthanide-fibroin composite

Abstract This work aims to produce luminescent sensors based on lanthanide ions and silk fibroin composite films. Associating the physicochemical properties of fibroin with the spectroscopic properties of lanthanide ions can be a strategy to develop a new generation of biocompatible and biodegradable sensors with high transparency in the visible region. The results presented herein are a natural consequence of a previous study that used europium ions as structural probes in the composite fibroin matrix and investigated their potential application as photonic devices. Here, highly transparent thin films containing the silk fibroin matrix and an Eu3+ complex were produced by dip-coating under controlled conditions. Europium thenoyltrifluoroacetonate was employed as the luminescent component of the proposed sensor. The films were characterized by electronic spectroscopy in the UV–Vis region and photoluminescence. The effect of complex insertion on the refraction index of the silk fibroin film was studied. The results showed a high-intensity emission that is characteristic of europium β-diketone chelates, and the intensity of the 5D0 → 7F2 transition depended on the ammonia vapor concentration. To understand the whole process, different composite films were prepared, and the results corroborated the potential use of this system as a photonic sensor of vapors.

Synthesis and Crystal Structures of Volatile Neptunium(IV) β-Diketonates.

Production of certified reference materials in support of domestic nuclear forensics programs require volatile precursors for introduction into electromagnetic isotopic separation instruments. β-Diketone chelates of tetravalent actinides are known for their high volatility, but previously developed synthetic approaches require starting material (NpCl4) that is prohibitively difficult and hazardous to prepare. An alternative strategy was developed here that uses controlled potential electrolysis to reduce neptunium to the tetravalent state in submolar concentrations of hydrochloric acid. Four different β-diketone ligands of varying degrees of fluorination were reacted with an aqueous solution of Np4+. Products of this reaction were characterized via X-ray diffraction and infrared spectroscopy, and were found to be neutral 8-coordinate complexes that adopt square antiprismatic crystal geometry. Synthesis of Np β-diketonates by this approach circumvents the necessity of using NpCl4 in tetravalent Np coordination compound synthesis. The volatility of the complexes was assessed using thermogravimetric analysis, where the temperature of sublimation was determined to be in the range of 180° to 205 °C. The extent of fluorination did not appreciably alter the sublimation temperature of the complex. Thermal decomposition of these compounds was not observed during sublimation. High volatility and thermal stability of Np β-diketonates make them ideal candidates for gaseous introduction into isotopic separation instruments.

Synthesis, crystal structure and luminescent properties of new tris-β-diketonate Eu(III) complex with thiadiazolophenanthroline derivative ligand

Herein we describe the synthesis, characterization and spectroscopic properties of the complex tris-(thenoyltrifluoroacetonate)([1, 2, 5]thiadiazolo[3, 4-f][1,10]phenanthroline) europium(III) acetonitrile solvate, [Eu(TTA) 3 TDPHEN] 1.5CH 3CN, where TTA = 2-thenoyl trifluoroacetone and TDPHEN = [1, 2, 5]thiadiazolo[3, 4-f][1, 10] phenanthroline. X-ray crystallography reveals that it is an eight-coordinate Eu(III) complex containing three β-diketonate chelates and one N, N′-bidentate ligand, [1, 2, 5] thiadiazolo[3, 4-f][1, 10] phenanthroline. The excitation at 340 nm of the europium complex in a solution of acetonitrile, and at room-temperature, showed the typical Eu(III) red emission as a sharp band at 611 nm, characteristic of Eu(III) due to the transition 5D 0 → 7F 2. This complex also showed red emission in the solid state phase ( λ em = 612 nm).

Shape-controlled Synthesis of Gold Nanoparticles from Gold(III)-chelates of β-diketones

Chelating ligands with β-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes out of aqueous HAuCl4 solutions. Evolution of stable gold nanoparticles happens to be first order with respect to gold particles having rate constants ∼ ∼10−2 min−1 and subsequent chlorine insertion in the β-diketone skeleton is reported as a general feature. Spherical or triangular or hexagonal particle evolution goes selectively under the influence of different β-diketones in terms of capping and reducing capabilities of the reductants.

Novel synergism by complex ligands in solvent extraction of rare earth metals(III) with β-diketones

The extraction of rare earth metals(III) (RE) with hexafluoroacetylacetone (Hhfa) and 2-thenoyltrifluoroacetone (Htta) was studied in the presence of some cobalt(III) chelates such as tris(acetylacetonato)cobalt(III), tris(4-isopropyltropolonato)cobalt(III), tris(8-quinolinolato)cobalt(III), tris(8-quinolinethiolato)cobalt(III), and tris(diethyldithiocarbamato)cobalt(III) in benzene or toluene. The synergistic enhancement of the extraction of RE, especially of lanthanum(III) was found in all the systems. Therefore, those cobalt(III) chelates act as synergists or complex ligands. The equilibrium analysis and IR spectroscopic study were performed to evaluate the present synergistic mechanism. It was found that the RE–β-diketone chelates form 1:1 adducts, i.e., binuclear complexes, with the cobalt(III) chelates in the organic phase. The formation constants ( β s,1) were determined and compared with those reported previously. The spectroscopic studies demonstrated that adducts have two different structures with inner- and outer-sphere coordination. In the former the cobalt(III) chelate directly coordinated to the RE ion and displaced the coordinated water molecules. In the latter the hydrogen-bonding was formed between the coordinating oxygen or sulfur atoms of cobalt(III) chelate and hydrogen atoms of the coordinated water molecules in the RE–β-diketone chelate. The types of the adducts are mainly due to the steric factors of the RE–β-diketone chelates and the cobalt(III) chelates.

Synthesis In Situ, Characterization, and Photostability of Europium β-Diketone Chelates in Organically Modified Silicates (ORMOSILs)

Europium β-diketonates have desirable optical properties, and transparent inorganic materials that have been doped with these chelates seem to be promising for potential applications in luminescence-display devices, integrated optical device sources, and new visible lasers. However, these chelates may be decomposed or not dissolved in sol—gel precursor solutions and, thus, cannot be doped in gel glasses that have been prepared via traditional sol—gel processing. An in situ synthesis technique has been used for the first time to synthesize five binary and ternary coordination compounds of europium β-diketonates in transparent organically modified silicates (ORMOSILs) during heat treatment or during the process of sol-to-monolithic ORMOSIL conversion. ORMOSILs that have been doped with in situ europium β-diketonates exhibit rather-high fluorescence intensity and good monochromati-city. These materials result in enhanced red-light emission under ultraviolet excitation. The chelates that have been synthesized in situ in the ORMOSILs reveal better photostability, in comparison to that of the pure chelates that have been dissolved in ethanol solutions.

Application of novel aerosol-assisted chemical vapor deposition techniques for SOFC thin films

Novel aerosol-assisted chemical vapor deposition (AACVD) techniques have been developed at the author's laboratory in the last decade, to prepare ceramic thin films mainly used as electrolyte and electrode materials for intermediate temperature and micro solid oxide fuel cell (SOFC). Four types AACVD including spray-aerosol-assisted metal-organic chemical vapor deposition (AAMOCVD), cold wall-AAMOCVD, microwave plasma-AACVD and combustion-AACVD have been designed and employed to prepare Y 2O 3-stabilized ZrO 2, Y 2O 3-doped CeO 2, Gd 2O 3-doped CeO 2 and La 0.8Sr 0.2MnO 3 thin films on various ceramic substrates. The metal β-diketonate chelates were chosen as the source materials for AAMOCVD. The structure, composition, morphology and electrical properties of these films were characterized. Thin film SOFC was also constructed and tested.

Synthesis and characterization of volatile metal β-diketonate chelates of M(DPM) n (M=Ce, Gd, Y, Zr, n=3,4) used as precursors for MOCVD

High pure Ce(DPM) 4, Gd(DPM) 3, Y(DPM) 3 and Zr(DPM) 4 (DPM=dipivaloylmethanate=2,2,6,6-tetramethyl-3,5-heptanedionato) powders were successfully synthesized from inorganic salts and HDPM in ethanol/aqueous solution followed by recrystallization from toluene. Freshly prepared samples have been characterized by elemental analysis, X-ray diffraction, thermogravimetry-differential thermal analysis, nuclear magnetic resonance spectroscopy and fourier transform infrared spectroscopy. Aged samples, obtained by exposing fresh ones into air for 30 days, were also represented. Various structures, stabilities and volatilities result from different metal atoms and coordination numbers. Those metal β-diketonate chelates are served as precursors of metalorganic chemical vapor deposition for single and multi-component oxide thin films.

Preparation of amorphous fluoride films by electron cyclotron resonance plasma-enhanced chemical vapor deposition

Amorphous ZnF 2, ZnF 2–BaF 2, AlF 3 and AlF 3–BaF 2 films were prepared on CaF 2(1 1 1) substrates by an electron cyclotron resonance plasma-enhanced chemical vapor deposition (CVD) technique. Metal β-diketone chelates and NF 3 gas were used as starting materials and a fluorinating gas, respectively. ZnF 2 films deposited on the substrates kept at 300°C and 100°C were crystalline and amorphous, respectively. The crystalline ZnF 2 thin film prepared at a deposition rate of 0.2 μm h −1 was oriented along a [1 1 0] direction. The amorphous ZnF 2 film, tinted yellowish brown, had an IR spectra which were due to contaminants. Colorless and contaminant-free amorphous films were obtained for a 60ZnF 2·40BaF 2 composition. On the other hand, AlF 3 films generated on the CaF 2(1 1 1) substrate kept at 300°C were amorphous and colorless. We also found that amorphous 80AlF 3·20BaF 2 and 60AlF 3·40BaF 2 films could be synthesized at a deposition rate of 1.5 μm h −1 .

Preparation of ZnF 2 and ZnF 2–BaF 2 thin films by electron cyclotron resonance plasma-enhanced chemical vapor deposition

Crystalline and amorphous ZnF 2 and ZnF 2-BaF 2 thin-films were prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition. The Zn and Ba β-diketone chelates and an NF 3 gas were used as starting materials and a fluorinating gas, respectively. Crystalline and transparent ZnF 2 thin-films were obtained on CaF 2(111) substrates kept at 300°C at the deposition rates of 0.2–0.8 μm/h. The thin film prepared at the 0.2 μm/h deposition rate was oriented along a [110] direction. The ZnF 2 thin-film deposited on a substrate kept at 100°C was amorphous though it tinted yellowish brown and had IR absorption bands due to contaminants. Colorless and contaminant-free amorphous thin-films were obtained in a 60ZnF 2·40BaF 2 composition.

Electrochemical Studies of the Stability of Copper β-Diketone Chelates

The voltammetric reduction of copper β-diketone chelates was used to get information on their complex stability. 1,1,1-Trifluoropentane-2,4-dione, pentane-2,4-dione, 1-phenylbutane-1,3-dione, 1,3-diphenylpropane-1,3-dione and 2,2,6,6-tetramethylheptane-3,5-dione were chosen as model ligands. The complexes were reduced in two separate steps the first of which proved to be reversible. The experimental data are suitable for calculation of the relative stability constants of corresponding Cu(I) and Cu(II) complexes. The data well correlate with the overall stability constants determined potentiometrically. The results were applied to some new hydrophobic β-diketones which are not accessible to potentiometric measurements.

Plasma-Enhanced MOCVD of Superconducting Oxides

AbstractThe plasma-enhanced MOCVD is developed to prepare high-Tc oxide superconducting thin films. Plasmas generated by microwave and rf discharges decompose effectively the source materials ( β-diketonate chelates) into their elements and oxides. YBaCuO thin films were deposited on the MgO substrate of 500–650 °C at total pressure of 0.6–5 Torr with O2 contents less than 30%. The as-grown films produced by two kinds of plasma enhancement were porous and consisted of crystalline grains, but showed the superconducting transition after heating procedure at around 800 °C. It is shown that the inherent crystalline orientations of the as-grown films determine the crystal structure of the post-annealed films. The film of the metal atomic ratios of 0.91 for Ba/Y and 2.64 for Cu/Y showed the superconducting properties with Tc(zero) of 89 K and the critical current density (at 77 K) of 5×104 A/cm2. Spectroscopic analysis showed that the plasmas are composed of many excited species such as Y, Y+, Ba, Ba+, Cu, YO, BaO, CuO. Formation of the metal-oxides through the gas phase reaction is essential for the high-quality YBaCuO superconducting thin film preparation in the PEMOCVD.

Preparation of ZrO<sub>2</sub>-Y<sub>2</sub>O<sub>3</sub> Films by CVD Using β-Diketone Metal Chelates

Films in the system ZrO2-Y2O3 were prepared at 600°to 1000°C by chemical vapor deposition using β-diketone chelates of Zr and Y and O2. The films having Y2O3 contents from 2 to 12% were obtained at various evaporatiorn temperatures of the sources. The films containing less than 3mol% Y2O3 were composed of cubic and tetragonal phases. The films containing more than 3mol% Y2O3 had a cubic crystal structure. The lattice parameter of the cubic phase increased. from 5.11 to 5.16A with increasing Y2O3 content. The deposition rates of the cubic-phase films at 620° and 660°C were 1.8 and 9.0μm/h, respectively. The film deposited at 660°C was composed of randomly oriented fine grains. Dendritic structures were observed for the films deposited above 660°C. The films exhibited a crystallographic orientation of (100) parallel to the substrate plane.

Preparation of lanthanide, thorium and uranium oxide films by chemical vapor deposition using β-diketone chelates

Preparation of thin film deposits of lanthanide, thorium and uranium oxides has been studied by chemical vapor deposition (CVD) method using β-diketonate metal chelates with 2,2,6,6-tetramethyl-3,5-heptanedione and some reactant gases as starting materials. The deposition process was carried out using a special apparatus designed for the CVD method at atmospheric pressure and temperatures as low as 400–600°C.As a result, it was demonstrated that each chelate used was well suited for the above purpose by its high volatility and reactivity with the reactant, especially with water vapor.

Preparation of yttrium barium copper oxide superconducting films by metalorganic molecular beam epitaxy

We have prepared yttrium barium copper oxide superconducting thin films on MgO(100) substrates by newly developed metalorganic molecular beam epitaxy. As source materials, we have used fluorine-free β-diketonate chelates of yttrium, barium and copper. The films annealed at 940°C had the c axis oriented normal to the substrate surface and exhibited superconducting properties with T c (zero resistance) = 45 K.

Mombe growth of superconducting oxide thin films

We have fabricated YBCO superconducting thin films on MgO(100) substrates by MOMBE. As source materials, we have used fluorine-free β-diketonate chelates of Y, Ba and Cu. The films annealed at 940 °C had the c-axis orieted normal to the substrate surface and showed the superconducting properties with Tc(zero resistance) of 45 K.

Preparation of lanthanide sulfide films by chemical vapor deposition using β-diketone chelates

Preparation of thin films of lanthanide (Ln) sulfides has been studied by the chemical vapor deposition (CVD) method, using metal β-diketonato chelates with 2,2,6,6-tetramethyl-3,5-heptanedione and reactant H2S gas as starting materials. Two kinds of sulfides, Ln2O2S oxysulfides and EuS monosulfide, were obtained as thin films at temperatures as low as 390–570 °C. The CVD method was confirmed to be suited for the above purpose.

Thermodynamical detection of hydrophobic hydration of tris(2,4-pentanedionato)-cobalt(III) and tris(3,5-heptanedionato)cobalt(III) in water

The solubilities of tris(2,4-pentanedionato)cobalt(III) and tris(3,5-heptanedionato)cobalt(III) in water, heptane, and 1,2-ethanediol were determined over the temperature range 5–50 °C and from these data the thermodynamic quantities of solution at 25 °C were estimated. The free energy [Formula: see text], enthalpy [Formula: see text], and entropy [Formula: see text] of transfer of these chelates from heptane to some solvents were calculated from the corresponding thermodynamic quantities of solution. When [Formula: see text] and [Formula: see text] were separately plotted against [Formula: see text], the data of transfer from heptane to water deviated markedly from a correlation obtained for the data of transfer to the solvents other than water. This finding indicates that these chelates are subject to hydrophobic hydration in their aqueous solutions. The solubility of tris(glycinato)cobalt(III) in water was also determined over the temperature range 5–60 °C and its temperature dependence of the solubility is compared with that for the cobalt(III) chelates of the β-diketones. Key words: tris cobalt(III) chelates of β-diketones and glycine, temperature dependence of solubility, thermodynamic parameters of solution, thermodynamic parameters of transfer, hydrophobic hydration.

Rapid Synthesis of the YBa2Cu3Ox Film on Metal Substrate by Chemical Vapor Deposition Technique

A new chemical vapor deposition technique has been developed for rapid (max. 24 µm/h) formation of the oxide superconductor film on a metal substrate. In this system, blended β-diketonate chelates of source materials were slowly fed to the vaporizer with carrier gas. The source gas from the vaporizer and O2 gas were introduced into the reactor. We realized a superconducting YBCO thin film that had a Tc=87 K on a Hastelloy C-276 substrate.