Lanthanide Coordination Research Articles

Coordination Chemistry and Antisolvent Strategy to Rare-Earth Solid Solution Colloidal Spheres

We have devised in this work a general synthetic strategy for preparation of single- and multicomponent rare-earth coordination polymer colloidal spheres (RE-CPCSs). This strategy is based on an integration of coordination chemistry and antisolvent effect for synchronized precipitation. Highly monodisperse RE-CPCSs with homogeneous mixing of RE elements, which are not readily attainable by any existing methods, have been successfully prepared for the first time. In addition, the type and molar ratio of these colloidal spheres can be adjusted easily in accordance to the variety and dosage of precursor salts. The molar ratio of RE elements in as-prepared colloidal spheres shows a linear relationship to that of starting reactants. Furthermore, the RE-based core/shell colloidal spheres can be facilely prepared by introducing other metal salts (beyond lanthanide elements) owing to their different coordination chemistry and precipitation behavior. By adjusting concentrations of the ionic activators, luminescent properties can be tuned accordingly. Moreover, the RE-CPCSs can be transformed to monodisperse lanthanide oxide spheres via simple heat treatment. We believe that the present synthetic strategy provides a viable route to prepare other lanthanide-containing colloidal spheres that have enormous potential for future applications as optoelectronic devices, catalysts, gas sensors, and solar cells.

Synthesis, Crystal Structures, and Luminescence Properties of Carboxylate Based Rare-Earth Coordination Polymers

Rare-earth coordination polymers or lanthanide-organic frameworks with hitherto unreported crystal structures have been obtained on the basis of the "light" lanthanides Pr, Nd, Sm, and Eu in combination with terephthalic acid and using a slightly altered literature synthesis procedure. Rietveld refinement has shown that powder XRD patterns of such compounds are largely dominated by the positions of the heavy elements, pointing to isostructural networks for all four terephthalate-based materials. An in-depth luminescence study has been performed on the reported MOFs, showing rare praseodymium and samarium emission in the visible spectrum, aside from the strong europium luminescence and the near-infrared emission from both a terephthalate and 2,5-pyridinedicarboxylate based neodymium-MOF.

Fluorite Topology in Lanthanoid Coordination Polymers with Di- and Trimetallic Building Blocks

Reaction of the pseudotetrahedral tetracarboxylic acid proligand tetrakis(4-carboxyphenyl)silane (H4L) with salts of various lanthanoid metals has afforded three new lanthanoid coordination polymers: {[H3O]2[Ce2(L)2(H2O)2]·2DMF·2H2O}∞ (1), {[Eu3L2(NO3)(DMF)4(H2O)]·0.5DMF·6H2O}∞ (2), and {Eu(HL)(DMF)2(H2O)]·DMF·2.5H2O}∞ (3) (DMF = N,N′-dimethylformamide), which have been structurally characterized by single-crystal X-ray diffraction. Compounds 1 and 2 are both noninterpenetrated three-dimensional networks that display the rare fluorite (CaF2) topology. In compound 1, the fully deprotonated L4– ligands act as pseudotetrahedral 4-connecting nodes and dinuclear cerium-carboxylate building blocks act as 8-connecting nodes, while in compound 2 the L4– ligands and trinuclear europium-carboxylate units are 4- and 8-connecting, respectively. In contrast, compound 3 exhibits a two-dimensional layered structure with triply deprotonated HL3– ligands acting as 3-connecting units, linking single europium centers within...

Solid state synthesis and photoluminescence of Sr3Y(P x V1 − x O4)3: Eu3 + submicrocrystalline rod

Using rare earth coordination polymers with ortho-hydroxylbenzoic acids as rare earth species and composing with organic polymers as the hybrid precursors, Sr3Y(P x V1 − x O4)3: Eu3 + (x = 0·1, 0·3, 0·5, 0·7, 0·9) phosphors has been synthesized. These phosphors present the column-like particles with a width of 250 nm and a length of 1 μ m. The value of red emission to orange emission for Eu3 + varies with the V content, indicating that the RO (red/orange) value increases with the increase of V content due to the lower electronegativity of V. Sr3Y(P0·3V0·7O4)3 has been shown to be the best composition among different compositions. Furthermore, the concentration quenching of Eu3 + in Sr3Y(P0·3V0·7O4)3 took place and the optimum concentration of Eu3 + is 5 mol % in the range of 1–9 mol %.

Synthesis, crystal structure, luminescent property and antibacterial activity of lanthanide ternary complexes with 2,4,6-tri(2-pyridyl)-s-triazine

Several ternary complexes of rare earth ions (RE3+ = Sm3+, Eu3+, Tb3+, Dy3+) with benzoic acid and a neutral ligand 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) have been synthesized. The crystal structure of the [Eu(C6H5COO)3(TPTZ)(H2O)]2·2C2H5OH·1.25H2O complex was determined by single-crystal X-ray diffraction and it is characteristic of triclinic with P−1 space group. Especially, the crystal has two types of coordination environment. One is mononuclear and the other is dinuclear. Each europium ion is nine-coordinately bonded to three nitrogen atoms of TPTZ, five oxygen atoms of three benzoic ions and one oxygen atom of water molecule. Furthermore, there exist three coordinate forms between C6H5COO− and Eu3+ ions in the crystal. One is chelating bidentate (two oxygen atoms), another is bridge coordinating (two oxygen atoms) and the other is monodentate (one oxygen atom). The compositions of these ternary complexes were characterized by elemental analysis, rare earth coordination titration, molar conductivity measurement, 1H NMR spectroscopy, IR spectroscopy and UV–vis absorption spectroscopy. The luminescence spectra and luminescence decay time were then studied. The luminescence intensities of the ternary complexes may result from the antenna effect of TPTZ and benzoic acid ligands as well as the reduce of solvent-quenching effect. Moreover, these ternary complexes exhibited superior antibacterial activity against Escherichia coli.

Synthesis, Characterization, and Thermodynamic Properties of the Rare Earth Coordination Complex [Sm(C6H4NO2)2·C9H6NO

This article reports the synthesis and thermodynamic properties of a novel rare earth coordination complex, samarium chloride hexahydrate (SmCl3·6H2O) with nicotinic acid (C6H5NO2) and 8-hydroxylquinoline (C9H7NO), whose composition and structure were characterized by elemental analysis, molar conductance, thermogravimetric analysis (TG–DTG), UV spectroscopy, IR spectroscopy, and X-ray powder diffraction. During the process of coordination, C6H5NO2 was bidentate-coordinated with the rare earth ion (Sm3+) through an acidic group that was formed by removing the proton; the hydroxyl oxygen atom and heterocyclic nitrogen atom of C9H6NO– formed a chelate ring with Sm3+ for coordination. The X-ray powder diffraction pattern demonstrated that the crystal type of [Sm(C6H4NO2)2·C9H6NO] is similar to that of C5H11NO2, with the cell parameters a = 5.426 nm, b = 22.105 nm, and c = 5.277 nm. At a constant temperature of 298.15 K, the dissolution enthalpies of the reactants and products of the coordination reaction in ...

General synthetic strategy for high-yield and uniform rare-earth oxysulfate (RE2O2SO4, RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, Ho, and Yb) hollow spheres

A general and facile synthetic strategy for fabrication of a series of high-yield and uniform rare-earth oxysulfate hollow spheres is demonstrated as the first example via calcination corresponding rare-earth coordination compounds obtained using L-cysteine as a biomolecular template. Furthermore, the hollow spheres can also be successfully doped or formed in a double-shell form for property modification and technological applications.

Two New Layered Lanthanide‐Carboxylate Coordination Networks with Unusual Topologies

AbstractTwo new rare earth coordination polymers, [Sm(HIDC)(ox)0.5(H2O)] (1) and [Pr(HIDC)(ox)0.5(H2O)2]·H2O (2) (H3IDC = 4, 5‐imidazoledicarboxylic acid, ox = oxalate), were synthesized under hydrothermal conditions and characterized by elemental analysis, TGA, and single‐crystal X‐ray diffraction. They exhibit novel (3, 4)‐connected double and single layered architectures with unprecedented (63)(66) and (4.52)(4.53.72) topologies, respectively. They are, to the best of our knowledge, the first examples constructed by IDC ligand combining with a second carboxylate ligand hitherto.

Syntheses, Crystal Structures and Photophysical Properties of a Series of LnIII (Ln = Sm, Tb, Pr) Coordination Polymers

Four new lanthanide(Ш) coordination polymers, [Ln(p-aminobenzoate)2(DMF)(HCOO) (H2O)]n (Ln = Sm 1, Tb 2, Pr 3) and {[Pr(2,5-dcp)(CH3COO)(H2O)]·1.5H2O}n (4) (DMF = N,N-dimethylformamide, 2,5-dcp = pyridine-2,5-dicarboxylate), have been synthesized by hydrothermal method. The structures are determined by the single-crystal X-ray diffraction. The four polymers all crystallize in the monoclinic space group P21/n. Polymers 1 and 2 are isostructural; both SmIII ion of polymer 1 and TbIII ion of polymer 2 are eight-coordinate. Although polymer 3 possesses the same asymmetric unit as polymers 1 and 2, the three are not isomorphous. The PrIII ions in polymers 3 and 4 are nine-coordinate. In polymers 1, 2 and 3 the neighboring units are bridged by formyloxy and extend into infinite chains, which are connected by hydrogen bonds to form a hydrogen bond network. However, polymer 4 is bridged by pyridine-2,5-dicarboxylate and acetates to form an infinite 3D network. At room temperature, the IR, UV–Vis–NIR and emission spectra of the four polymers were measured and analyzed. The four polymers emit in the visible or NIR region. The luminescent properties are discussed.

Poly[(μ(4)-benzene-1,3,5-tricarboxyl-ato)bis-(N,N-dimethyl-formamide)-cerium(III)

The asymmetric unit of the title rare earth coordination polymer, [Ce(C9H3O6)(C3H7NO)2]n, contains one eight-coordinated Ce3+ ion, one benzene-1,3,5-tricarboxyl­ate (BTC) ligand and two coordinated N,N-dimethyl­formamide (DMF) mol­ecules. The Ce3+ ion is coordinated by six O atoms from four carboxyl­ate groups of the BTC ligands and by two O atoms from two terminal DMF mol­ecules.

Intensity-tunable micelles and films containing bimetal ions—europium(III) and terbium(III)

In this paper, multicolored micelles were prepared by coordination of lanthanide(III) (europium(III) (Eu(III)) and terbium(III) (Tb(III))) ions with block copolymer in different molar ratios of nEu(III)/nTb(III). The micelles formed by polymer–Eu(III)/Tb(III) could emit higher quantum yield luminescence than the mixture of polymer–Eu(III) micelles and polymer–Tb(III) micelles. The micelles containing Eu(III) and Tb(III) could emit a yellow-green color, and the intensity varied with the molar ratios of nEu(III)/nTb(III). In the constant concentrations of Eu(III) and 1,10-phenanthroline (Phen), the intensity of 5D0→7F2 increased with the addition of Tb(III), and the intensity of 5D4→7F5 decreased with the increasing of Eu(III) in the constant concentrations of Tb(III) and Phen. All the multicolored micelles could be spin-coated as intensity-tunable films.

Effects of Acidity on Nitrogen-Heterocyclic Compounds with Rare Earth Coordination and the Structure of Protonated Phenanthroline

2,3-bis(2-pyridyl)-5,6-dihydropyrazine and a protonated phenanthroline (Phen) have been synthesized and the structure of protonated Phen is established by X-ray diffraction single crystal structure analysis. The coordination reactions of Phen, 2,2'- bipyridine and 2,3-bis(2-pyridyl)-5,6-dihydropyrazine with rare earth ions in low pH have been studied. The results show that 2,3-bis(2-pyridyl)-5,6-dihydropyrazine is hydrolyzed to be 2,2’-pyridil and protonated ethylenediamine. Meanwhile, Phen combines with proton, which results that nitrogen atoms can not coordinate with rare earth ions. The molecular formula of protonated Phen is C12H8N2HCl·H2O. It crystallizes in the triclinic space group P -1 (2), with a = 7.1212(14) Å, b = 7.2786(15) Å, c = 20.817(4) Å, α = 90.00º, β = 96.69(3) º, γ = 90.00 º, V = 1071.65(379) Å3, Z = 4.

Synthesis, characterization and luminescence property of ternary rare earth complexes with azatriphenylenes as highly efficient sensitizers

A series of novel ternary rare earth complexes showing attractive luminescence properties were prepared with both neutral and anion ligands. Three azatriphenylene neutral ligands, 1,10-phenanthroline (phen), dipyrido [3,2-a: 2′,3′-c] quinoxaline (dpq) and dipyrido [3,2-a: 2′,3′-c] phenazine (dppz) were investigated systematically as sensitizers in the ternary rare earth complexes. Benzoate ions (BA −) and phenoxyacetate ions (POA −) were chosen as anion ligands. The compositions of these complexes were characterized by elemental analysis, rare earth coordination titration, molar conductivity measurement, IR spectroscopy, UV–vis absorption spectroscopy, 1H NMR spectroscopy and TGA–DTA. The luminescence spectra, luminescence decay time and quantum efficiency of the complexes were also studied. The very strong luminescence intensities and rather long luminescence lifetimes (typically > 1.0 ms) were achieved for both Eu 3+ and Tb 3+ ternary complexes with phen and dpq as neutral ligands. Moreover, high quantum efficiencies (40–60%) were also obtained for Eu 3+ ternary complexes with phen and dpq as neutral ligands.

Structure of praseodymium and neodymium gallate glasses

The rare-earth gallate glasses R 4Ga 6O 15, where R denotes Pr or Nd, were prepared using an aerodynamic levitator and laser heating system. The structure was studied by applying the method of isomorphic substitution in neutron diffraction which allows for an identification of the gallium and rare-earth coordination environments. The results give a mean Ga–O coordination number of 4.2(1) at a distance of 1.85(2) Å and a mean R–O coordination number of 7.4(2) at a mean distance of 2.38(2) Å. The experimental results are consistent with a glass network built from GaO 4 tetrahedra and with the presence of GaO 6 octahedra at the 10(5)% level.

Large reversible magnetocaloric effect due to a rather unstable antiferromagnetic ground state in Er4NiCd

Er 4 NiCd crystallizes with the Gd4RhIn type structure, space group F4¯3m, a=1333.3 pm. The nickel atoms have trigonal prismatic rare earth coordination. Condensation of the NiEr6 prisms leads to a three-dimensional network which leaves voids that are filled by regular Cd4 tetrahedra. Er4NiCd shows Curie–Weiss behavior above 50 K with TN=5.9 K. At field strength of 4 kOe a metamagnetic step is visible, together with the positive paramagnetic Curie-temperature (7.5 K) indicative for the rather unstable antiferromagnetic ground state. Therefore, a large reversible magnetocaloric effect (MCE) near the ordering temperature occurs and the values of the maximum magnetic-entropy change −ΔSMmax reach 18.3 J kg−1 K−1 for the field change of 5 T with no obvious hysteresis loss around 17 K. The corresponding RCP of 595 J kg−1 is relatively high as compared to other MCE materials in that temperature range. These results indicate that Er4NiCd could be a promising system for magnetic refrigeration at temperatures below liquid H2.

Structures and luminescent properties of Sm(III) and Dy(III) coordination polymers with 2,4,6-pyridinetricarboxylic acid

Two rare earth coordination compounds with 2,4,6-pyridinetricarboxylic acid (H3pta) have been synthesized by the hydrothermal method; the formula is {[RE(pta)(H2O)3] · H2O} n [RE = Sm (1) and Dy (2)]. Complexes 1 and 2 are crystallized in the monoclinic crystal system with P21/c space group. X-ray structure analyses show the two complexes have the same structure. Each pta3− connects three rare earth ions. Both the Sm(III) and Dy(III) complexes exhibit characteristic luminescence in the visible region upon excitation with UV-rays.

Study on the influence of metal residue on thermal degradation of poly(cyclohexene carbonate)

Poly(cyclohexene carbonate) (PCHC) is an alternative copolymer of carbon dioxide and cyclohexene oxide. Severe thermal decomposition occurs during melt processing of PCHC, thus, it is important to find the reason for thermal decomposition and raise its thermal stability. In this report, as-polymerized PCHC was obtained under Y(CCl3COO)3-ZnEt2-glycerin rare earth coordination ternary catalyst. The pyrolysis gas chromatography with mass spectrometry analysis disclosed that chain unzipping depolymerization dominated the thermal decomposition process. The residue metal (mainly ZnO in this catalyst system) was important in PCHC degradation, and the onset decomposition temperature of PCHC containing 5 ppm zinc was 56 °C higher than that of PCHC containing 4,400 ppm Zn, corresponding to apparent activation energy change from 190 KJ/mol to 146 KJ/mol. When PCHC was subjected to melt processing, its average molecular weight decreased more rapidly, as it contained more catalyst residue, indicating metal residue in PCHC could accelerate the decomposition process, and removing the metal residue should be effective in raising its thermal stability.

Studies on the Effect of Various Anions and Pyridine on the Stereochemistry of Lanthanide(III) Coordination Compounds of 4[N-(2′-Hydroxy-1′-Naphthalidene)Amino] Antipyrine Thiosemicarbazone

In the present studies, the effect of pyridine on stereochemistry of the coordination compounds of lanthanide(III) derived from 4[N-(2′-hydroxy-1′-naphthalidene)amino] antipyrine thiosemicarbazone (HNAAPTS) has been studied. The general composition of the present complexes is LnX3·n(HNAAPTS)·Py (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, or Ho; X = NO3, n = 1, x = Cl, NCS or ClO4, n = 2, Py = pyridine). All the complexes were characterized by elemental analyses, molecular weight, molar conductance, magnetic susceptibilities, infrared and electronic spectral studies. The infrared studies reveal that the HNAAPTS behaves as a neutral tridentate (N, N, S), while pyridine is coordinated to metal ions via its nitrogen atom. Nitrates are bicovalently bonded, while thiocyanate is coordinated through a strong N-atom. Perchlorate ions are not coordinating in coordination sphere. From electronic spectral data, nephelauxetic effect (β), covalence factor (b½), Sinha parameter (δ%), and the covalence angular overlap parameter (η) have been calculated. Thermal stabilities of these complexes were studied by thermogravimetric analysis. In conclusion, the coordination number of lanthanides(III) in the present compounds is either seven or ten depending on the coordinating anions. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Coordination sphere geometry changes of lanthanoid(III) nitrate complexes with hexamethylenetetramine

The 1 : 2 adducts of lanthanoid nitrate complexes with hexamethylenetetramine (hmta) have been synthesized and characterized by X-ray crystallography, IR spectroscopy, and bond valence calculations. The effect of lanthanoid contraction is observed. The lanthanoids create three isostructural groups: La–Nd (group I), Sm–Gd (group II), and Dy–Lu (group III). As an example, one structure for each group is presented in detail. There is a change in the composition of the lanthanoid coordination sphere, geometry, and coordination number with changing size of the lanthanoid. As the ionic radii decrease, the number of water molecules increases, whereas the nitrate ions move outside the inner coordination shell forming three isostructural groups. The hmta molecules are not coordinated to the central atom. Group I is formed by 10-coordinate complexes with the nitrate ions and water molecules in the inner and outer coordination sphere ([Ln(NO3)2(H2O)6]+ · · 2hmta · 2H2O). Group II includes the adducts of general formula ([Ln(NO3)(H2O)7]2+ · 2 · 2hmta · 3H2O) with nine-coordinate lanthanoid. Group III consists of eight-coordinate lanthanoid with general formula [Ln(H2O)8]3+ · 3 · 2hmta · 2H2O].

Synthesis and fluorescence properties of novel 1,10‐phenanthroline‐functionalized polyaryletherketone and its rare earth complexes

Abstract1,10‐Phenanthroline‐functionalized polyaryletherketone (PPEK) was synthesized by the amidation reaction of 5‐amino‐1,10‐phenanthroline with polyaryletherketone containing pendant acyl chloride groups. Subsequently, a series of novel rare earth coordination polymers (with rare earths Eu3+, Tb3+, Sm3+ and Dy3+) were prepared, using PPEK as macromolecular ligand and the small 1,10‐phenanthroline (Phen) molecule as synergistic ligand. Their structures were characterized using Fourier transform infrared spectroscopy, elemental analysis and X‐ray diffraction, which confirmed that both PPEK and Phen participated in the coordination reaction with the rare earth ions, and that the rare earth ions could disperse homogeneously in the polymer matrix. The rare earth coordination polymers were soluble in polar solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide and N‐methylpyrrolidone, and could be easily cast into transparent tough thin films. Fluorescence measurements indicated that all the coordination polymers exhibited the intense characteristic fluorescence of the corresponding rare earth ions under ultraviolet excitation, showing their application potential in optical display devices. Copyright © 2010 Society of Chemical Industry