A novel 2D arsenic vanadate network grafted with a transition metal complex: [Cu(phen)][(VV4As2O19)-V-IV-As-V]center dot 0.5H(2)O

A novel organic-inorganic hybrid compound [Cu(phen)](2)[(VV4As2O19)-V-IV-As-V-O-V].0.5H(2)O 1 has been hydrothermally synthesized. Its structure, determined by single crystal X-ray diffraction, exhibits an unusual two-dimensional arsenic vanadate layered network grafted with the [Cu(phen)](2+) complex. The chelating phen ligands project perpendicularly beyond the inorganic layer. Variable temperature magnetic susceptibility studies indicate that both ferro- and antiferro-magnetic interactions exist in 1.

A two-dimensional molybdenum (V) phosphate with covalently bonded transition metal coordination complexes: hydrothermal synthesis and structure characterization of Na-2[{Mn(phen)(2)(H2O)}{Mn(phen)(2)}(3){Mn (Mo12O24)-O-V (HPO4)(6)(PO4)(2)(OH)(6)}] center dot 4H(2)O (phen=1,10-phenanthroline)

An organic-inorganic hybrid molybdenum phosphate, Na-2[{Mn(phen)(2)(H2O)} {Mn(phen)(2)}(3){(MnMo12O24)-O-v (HPO4)(6)(PO4)(2) (OH)(6)}] . 4H(2)O (phen=1,10-phenanthroline), involving molybdenum present in V oxidation state and covalently bonded transition metal coordination complexes, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Deep brown-red crystals are formed in the triclinic system, space group P (1) over bar, a=16.581(l)Angstrom, b=18.354(1)Angstrom, c=24.485(2)Angstrom, alpha=80.589(l)degrees, beta=71.279(1)degrees, gamma=67.084(1)degrees, V=6493.8(8)Angstrom(3), Z=2, lambda(MoKalpha)=0.71073Angstrom (R(F)=0.0686 for 29,053 reflections). Data were collected on a Bruker Smart Apex CCD diffractometer at 293 K in the range of 1.76 < theta < 28.06degrees using omega-2theta scans technique. The structure of the title compound may be considered to be based on {Mo6O12(HPO4)(3)(PO4)(OH)(3)} units bonded together with {Mn(phen)(2)} subunits into a two-dimensional network. Two types of tunnels are observed in the solid of the title compound.

The optical spectroscopic properties of rare earth-activated barium orthophosphate in VUV-Vis range

The optical properties of rare earth ions-activated barium orthophosphate phosphors, Ba-3(PO4)(2):RE (RE = Ce3+, Sm3+, Eu3+, Eu2+, and Tb3+), were investigated in vacuum ultraviolet (VLTV)-Vis range. A band-band transition Of PO43- in Ba-3(PO4)(2) is observed in the region of 150-170 nm. The partial reduction of Eu3+ to Eu2+ was observed and confirmed by luminescent spectra under the VUV-UV excitation. It is proposed that the electronegative defects that formed by aliovalent substitution of Eu3+ on the Ba2+ site in the host are responsible for the reduction process.

VUV-UV excited luminescent properties of calcium borophosphate doped with rare earth ions

The VUV-UV spectra of rare earth ions activated calcium borophosphate, CaBPO5:RE (RE = Ce3+, sm(3+), Eu2+, Eu3+, Tb3+ and Dy3+) were determined. The bands at about 155 nm in the VUV excitation spectra are attributed to the host lattice absorptions. The bands at 166 and 190 nm for the sample CaBPO5:Sm have been considered as related to the f-d transition and the charge transfer band (CTB) of Sm3+ ions, and the band at 169 nm for the sample CaBPO5:Dy is assumed to be connected with the f-d transition of the Dy3+ ions in CaBPO5. The partial reduction of Eu3+ CaBPO5:Eu prepared by high temperature solid state reaction in air is confirmed by the VUV-UV spectra.

Preparation of rare earth ion induced conformation-specific anti-calmodulin monoclonal antibody

Monoclonal antibody technique was employed to detect the conformational change of calmodulin induced by metal ions. Bovine calmodulin was firstly modified by 2,4-dinitrofluorobenzene to improve its immunogenicity, then, the derived protein was saturated with trivalent europium ions and injected to Balb/c mice as antigen. After four times of immunization, a corresponding antibody was detected and its titer in serum was determined as 1 : 12 000. By fusing of the spleen cells with hybridoma cells, a europium induced conformation-specific anti-calmodulin monoclonal antibody cell strain named as 2C3 was produced successfully. The molecular recognition ability of antibody to apocalmodulin and holocalmodulin showed a significant difference, indicating that this antibody could be applied to the studies of different effects of metal ions on the conformational change of calmodulin and its interaction with target molecules.

Layer-by-layer multilayer films self-assembled from a rare-earth-containing poly-oxometalate Na-9[Eu(W5O18)(2)] and poly (allylamine hydrochloride) and their photoluminescent properties

Ultrathin multilayer films of a rare-earth-containing polyoxometalate Na-9[Eu(W5O18)(2)] (EW) and Poly (allyamine hydrochloride) (PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solutions. The fabrication process of the EW/PAH multilayer films was followed by UV-vis spectroscopy and ellipsometry, which show that the deposition process is linear and highly reproducible from layer to layer. An average EW/PAH bilayer thickness of ca. 2.1 nm was determine,by ellipsometry. In addition, the scanning electron microscopy (SEM) image of the EW/PAH film indicates that the film sufface is relatively uniform and smooth. The photoluminescent properties of these films were also investigated by fluoresence spectroscopy.

Preparation and luminescence properties of the mesoporous MCM-41s intercalated with rare earth complex

Rare earth complex Eu(DBM)(3)phen (DBM: dibenzoylmethane, phen: 1.10-phenanthroline) hits been incorporated into unmodified MCM-41 and modified MCM-41s by aminopropyltriethoxysilane (APTES) or N-[(3-triethoxysilyl)propyl]ethylenediamine(TEPED). Thus, the assemblies of unmodified or modified MCM-41s with rare earth (RE) complex have been obtained. XRD spectra. NMR spectra. diffuse reflectance spectra. and the luminescence spectra were used to characterize the pure RE complex and the corresponding assemblies. The assemblies have better luminescence properties under UV irradiation. and their fluorescence lifetimes on the excited state are longer than that of the corresponding pure complex. The possible mechanisms are also discussed in the context.

Photoluminescent organic-inorganic composite films layer-by-layer self-assembled from the rare-earth-containing polyoxometalate Na-9[EuW10O36] and poly(allylamine hydrochloride)

Photoluminescent organic-inorganic composite films incorporating the rare-earth-containing polyoxometalate Na-9[EuW10O36] (EW) and poly(allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer self-assembly method. UV-vis spectroscopy and ellipsometry were used to follow the fabrication process of the EW/PAH composite films. The experimental results show that the deposition process is linear and highly reproducible from layer to layer. An average EW/PAH bilayer thickness of ca. 2.1 nm was determined by ellipsometry. In addition, scanning electron microscopy and atomic force microscopy images of the EW/PAH composite films indicate that the film surface is relatively uniform and smooth. The photoluminescent properties of these films were investigated by fluorescence spectroscopy.

Chemical bond parameters in Sr3MRhO6 (M=rare earth)

Chemical bond parameters, that is, bond covalency, bond valence, macroscopic linear susceptibility, and oxidation states of elements in Sr3MRhO6 (M=Sm, Eu, Tb, Dy, Ho, Er, Yb) have been calculated. The results indicate that the bond covalency of M-O decreases sharply with the decrease of ionic radius of M3+ from Sm to Yb, while no obvious trend has been found for Rh-O and Sr-O bonds. The global instability index indicates that the crystal structures of Sr(3)MrhO(6) (M = Sm, Eu, Tb, Dy, Ho) have strained bonds.

Effects of rare earth ions and calmodulin on the activity of lactate dehydrogenase

In this paper, the effects of rare earth ions (La3+, Eu3+, Dy3+, Yb3+) and their complexes with calmodulin on the activity of lactate dehydrogenase (LDH) were investigated. The results reveal that whether binding with calmodulin or not, rare earth ions show a minor activation effects on LDH when their concentrations are less than 3 mu mol (.) L-1, but indicate some strong inhibitory effects on LDH activity when the concentrations are above 5 mu mol (.) L-1. Calmodulin, which is a calcium-dependent regulator, can stimulate LDH activity and release the inhibitory effects of rare earth ion. Diethylenetriamine pentaacetic acid(DTPA) and its derivatives bisdimethylamide-diethylenetriamine pentaacetic acid (DTPA-BDMA), bisisonicotinyl-diethylenetriamine pentaacetic acid (DTPA-BIN), which are often used as ligands to metal ions, inhibit LDH activity when their concentrations are above 5 mu mol (.) L-1. Calmodulin can also release their inhibitory effects at the same time.

Classification of valence changes of trivalent rare earth ions in alkaline earth borates using artificial neural networks

The investigations of classification on the valence changes from RE3+ to RE2+ (RE = Eu, Sm, Yb, Tm) in host compounds of alkaline earth berate were performed using artificial neural networks (ANNs). For comparison, the common methods of pattern recognition, such as SIMCA, KNN, Fisher discriminant analysis and stepwise discriminant analysis were adopted. A learning set consisting of 24 host compounds and a test set consisting of 12 host compounds were characterized by eight crystal structure parameters. These parameters were reduced from 8 to 4 by leaps and bounds algorithm. The recognition rates from 87.5 to 95.8% and prediction capabilities from 75.0 to 91.7% were obtained. The results provided by ANN method were better than that achieved by the other four methods. (C) 1999 Elsevier Science B.V. All rights reserved.

Synthesis, characterisation and catalytic activity of propionamide complexes of rare earth chlorides

Propionamide complexes of rare earth chlorides were synthesized, Formula of the complexes is LnCl(3). 3BA. The ligand is shown to behave as a normal amide donor With the oxygen of the carbonyl group coordinated to the metal ions. Binary system composed Elf propionamide and aluminum alkyl shows higher activity and stereospecificity for butadiene polymerization. The cis-1,4 content of polybutadiene is more than 98%.

Chemical bond properties of rare earth ions in crystals

By using the dielectric description theory of ionicity of solids, chemical bond properties of rare earth ions with various ligands are studied. Calculated results show that chemical bond properties of the same rare earth ion and the same ligand in different crystals depend on the crystal structures. In a series of compounds, chemical bond properties of crystals containing different rare earth ions are similar. The magnitude of covalency of chemical bonds of trivalent rare earth ions and various ligands has an order like F

Extraction and separation of heavy rare earth (III) with Extraction Resin containing di(2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272)

Extraction resins, of the type of;levextrel, (which is a collective term for styrene/divinylbenzene based copolymers of predominantly macroporous structure that contain a selective extractant) are important for the recovery and separation of metal ions, as they combine features of solvent extraction and ion exchange resins. This paper presents the results of the adsorption of heavy rare earth ions (Ho(III), Er(III), Tm(III), Yb(III), Lu(III) and Y(III)) from hydrochloric acid solutions at 0.2 mol/L ionic strength and 50 degrees C by the extraction resin containing di (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272) and the chromatographic separation of (Er(III), Tm(III) and Yb(III)). Technological separation products, with purity and yield of Tm2O3 >99.97%, >80%, Er2O3 >99.9%, >94% and Yb2O3 >99.8%, >80% respectively, have been obtained from a feed having the composition Tm2O3 60%, Er2O3 10%, and Yb2O3 3%, the others 27%. The distribution coefficients, extraction equilibrium constants and separation factors have been determined as a function of acidity, loading of the resin and rare earths, flow rates and column ratios. The resolutions and efficiencies of separation of Er/Tm/Yb each other have been calculated. The stoichiometry of the extraction of rare earth ions has been suggested as well.

Catalysis of the rare earth containing mixed oxides Ln(2)CuO(4) in phenol hydroxylation

Mixed oxides Ln(2)CuO(4+/-lambda)(Ln = La, Pr, Nd, Sm, Gd) with K2NiF4 structure were prepared. Their crystal structures were studied with XRD and IR spectra. Meanwhile, the average valence of Cu ions and nonstoichiometric oxygen (lambda) were determined through chemical analyses. Catalysis of the above-mentioned mixed oxides in the phenol hydroxylation was investigated. Results show that the catalysis of these mixed oxides has close relation with their structures and composition. Substitution of A site atom in Ln(2)CuO(4+/-lambda) has a great influence on their catalysis in the phenol hydroxylation.