Organic electroluminescent devices using rare earth complex Eu(DBM)(3) as an emitter

Eu3+ narrow band emitting EL device with PPV, Alq(3) as hole and electron transportation layers has been prepared. The emitting layer, which consists of PVK, Eu(DBM)(3) and PBD is formed by spin-casting method. A maximum luminance of 52cd.m(-2) is achieved from the device.

Synthesis of isotactic polystyrene with a rare-earth catalyst

Polymerization of styrene with the neodymium phosphonate Nd(P-507)/H2O/Al(i-Bu)(3) catalytic system has been examined. The polymer obtained was separated into a soluble and an insoluble fraction by 2-butanone extraction. C-13-NMR spectra indicate that the insoluble fraction is isotactic polystyrene and the soluble one is syndiotactic-rich atactic polystyrene. The polymerization features are described and discussed. The optimum conditions for the polymerization are as follows: [Nd] = (3.5-5.0) x 10(-2) mol/L; [styrene] = 5 mol/L; [Al]/[Nd] = 6-8 mol/mol; [H2O]/[Al] = 0.05-0.08 mol/mol; polymerization temperature around 70 degrees C. The percent yield of isotactic polystyrene (TY) is markedly affected by catalyst aging temperature. With increase of the aging temperature from 40 to 70 degrees C, TY increases from 9% to 48%. Using AlEt3 and Al(i-Bu)(2)H instead of Al(i-Bu)(3) decreases the yield of isotactic polystyrene. Different neodymium compounds give the following activity order: Nd(P-507)(3) > Nd(P-204)(3) > Nd(OPri)(3) > NdCl3 + C2HF5OH > Nd(naph)(3). With Nd(naph)(3) as catalyst, only atactic polystyrene is obtained. (C) 1998 John Wiley & Sons, Inc.

Luminescence properties of the rare earth (Eu3+ and Tb3+) complexes with 1,10-phenanthroline incorporated in silica matrix by a sol-gel method

Europium and terbium complexes with 1,10-phenanthroline were introduced into silica gel by the sol-gel method. The luminescence behavior of the complexes in silica gels was studied compared with the corresponding solid state complexes by means of emission, excitation spectra and lifetimes. (C) 1998 Published by Elsevier Science S.A. All rights reserved.

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.

Spectroscopic study of luminescence and energy transfer of binary and ternary complexes of rare earth with aromatic carboxylic acids and 1,10-phenanthroline

A series of rare earth (Gd, Eu, Tb) complexes with different substituent group carboxylic acids (ortho-hydroxylbenzioc acid, ortho-aminobenzoic acid and ortho-methoxy benzoic acid) and 1,10-phenanthroline were synthesized. The spectroscopic studies of the photophysical properties such as luminescence properties, energy match and intramolecular energy transfer were carried out. The lowest triplet state energies of ligands and the intramolecular energy transfer efficiencies were determined with the measurement of low phosphorescence spectra and lifetimes of Gd complexes.

Photophysical properties of some binary and ternary complexes of rare earth ions with aminobenzoic acids and 1,10-phenanthroline

Photophysical properties (e.g. luminescence and energy transfer) of binary and ternary complexes of Gd3+, Eu3+, and Tb3+ with aminobenzoic acids and 1,10-phenanthroline were studied in connection with their spectroscopic characterization. Intramolecular energy transfer between center ions and ligands as well as between ligands is discussed in detail.

A novel rare earth coordination catalyst for polymerization of biodegradable aliphatic lactones and lactides

A novel rare earth coordination system composed of lanthanide trifluoroacetates Ln(CF3COO)(3) (Ln = Y, Yb, Nd, Tm, Ho, La, Pr) and triisobutylaluminium Al(i-Bu)(3) was used as catalyst for the polymerization of epsilon-caprolactone (CL), D,L-lactide (DLLA) and their copolymerization. The influence of temperature, time and catalyst concentration on polymerization yields and molecular weights of the polyesters have been studied. It was shown that the ring-opening polymerization of cyclic esters catalysed by Ln(CF3COO)(3)/Al(i-Bu)(3) has some living character and the molecular weight of the polyester could be controlled by adjusting the molar ratio of monomer to catalyst. The DLLA/CL copolymer was synthesized by sequential addition of monomers and the structure of the copolyester was characterized by GPC, NMR and DSC. (C) 1998 SCI.

Synthesis, luminescence and intramolecular energy transfer of binary and ternary rare earth complexes with aromatic carboxylic acids and 1,10-phenanthroline

A series of binary and ternary rare earth complexes with para-substitued benzoic acids and 1,10-phenanthroline were synthesized. The phosphorescence spectra were measured and the lowest tripler state energies of ligands were determined, the phosphorescence lifetimes were obtained and intramolecular energy transfer mechanism between ligands was studied. The luminescence properties were also measured and were in agreement with the prediction. The energy match and intramolecular energy transfer process in these binary and ternary complexes were discussed in detail.

Studies on extracting solutions of endohedral rare-earth metallofullerenes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Thirteen extracting solutions of rare-earth metallofullerenes containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb respectively have been investigated by means of matrix-assisted laser desorption/ionization time-of-night, mass spectrometry. The influences of the positive-ion/negative-ion mode, laser intensity, matrix and mass discrimination to the analytical results are studied, based on which the optimal analytical conditions have been determined. The results show that the extracting solutions contain large quantities of rare-earth metallofullerenes brs;des empty fullerenes, On the basis of comparing their relative intensities, the different structure stabilities and solubilities of metallofullerenes with different rare-earth metals encapsulated into the fullerene cages, as well as some possible reasons to those differences, are discussed.

Irradiation damage on BaLiF3 crystallites and its suppression by rare-earth ion doping

The x-ray and gamma-ray induced damage in BaLiF3 crystallites and its suppression by rare earth ion doping have been studied by electron spin resonance and thermally stimulated luminescence methods. It has been found that the x-ray irradiation damage is light and can be erased easily. This shows that the BaLiF3 crystallite is an ideal host for x-ray storage material. But the damage induced by gamma-ray has been found to be relatively hard to recover; however the gamma-ray irradiation hardness can be improved by rare earth (e.g., La3+, Yb3+) ion doping. So the BaLiF3 is also promising material for being used in detection of high-energy particles (e.g., gamma-ray).

Synthesis, luminescence properties and energy transfer of binary and ternary rare earth complexes with aromatic acids and 1,10-phenanthroline

A series of binary and ternary rare earth (Gd, Eu, Tb) complexes with ortho hydroxyl benzoic acid, pam aminobenzoic acid, nicotinic acid and 1,10-phenanthroline were synthesized. Phosphorescence spectra and lifetimes of Gd complexes were measured and the lowest triplet state energies of gadolinium binary complexes end the intramolecular energy transfer efficiencies were determined. The luminescence properties and energy transfer process of Eu3+ and Tb3+ complexes were discussed.

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.

Gas Phase Addition of Rare-earth Fullerenes with Benzene

Gas phase adduct of endohedral rare-earth fullerenes Nd@C-S2 with the ion system of benzene-[Nd@C-S2-C6H6](+) was observed for the first time by ion-molecular reaction under chemical ionization condition. The possible reaction passageway and molecular structures of this gas phase adduct were discussed and a parallel "reversed umbrella" pi-pi interaction complex of the [C6H6](+) ion reacting with the neutral rare-earth fullerenes Nd@C-S2 was considered to be much reasonable. The experimental result indicated that endohedral rare-earth fullerenes has relatively active reactivity and aromatic properties similar towards benzene molecular ion in gas phase.

The synthesis, luminescence and energy transfer of the binary and ternary complexes of rare earth with aminobenzoic acids and 1,10-phenanthroline

Thirteen kinds of binary and ternary complexes of rare earth (Gd, Eu,Tb) with ortho (para) aminobenzoic acid and 1.10--phenanthroline were synthesized and characterized. The phosphorescence spectra and lifetimes of gadolinium complexes were measured and the lowest triplet state energies of ligands and the energy transfer efficiencies between ligands were determined. The luminescence properties and intramolecular energy transfer of these complexes were studied in details.