- Rare earth ethenide-halides Ln2n+6(C2) n+4X2n+2: Preparation, crystal structure, intergrowth and twinning
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Preparation, crystal structure, intergrowth and twinning of the compounds La10(C2)6Br6, Ce10(C 2)Br6 and Gd10(C2) 6(Cl6 are described.
- Mattausch, Hansjuergen,Kienle, Lorenz,Duppel, Viola,Hoch, Constantin,Simon, Arndt
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- Sonoluminescence of aqueous solution of gadolinium chloride
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A line of the GdIII ion was detected at 311 nm in the multibubble sonoluminescence spectrum of a concentrated (1 mol L-1) solution of gadolinium chloride. A comparison with the earlier studied sonoluminescence of the CeIII and TbIII ions shows that the GdIII ion is excited in the volume and/or on the surface of cavitation bubbles upon collisions with hot particles. The efficiency of excitation of the lanthanide ions via this mechanism depends on the type of electron transition. For the same energy of the excited state, the efficiency of GdIII excitation (f-f transition) exceeds by at least 50 times that of CeIII excitation (f-d transition).
- Sharipov,Gainetdinov,Abdrakhmanov
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- Formation of coordination compounds in gadolinium-loaded liquid organic scintillators (GdLS): Use of mixed-ligand gadolinium complexes in GdLS preparation
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The formation of coordination compounds between gadolinium 2-methylvalerate (Gd(2MVA)3) and trioctylphosphine oxide (TOPO) in a gadolinium-loaded liquid scintillator (GdLS) solution was studied by MALDI-TOF MS. The most abundant gadolinium-cont
- Novikova,Barabanov,Bezrukov,Belous,Danilov,Ivanov,Ziganshin,Yanovich
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- Raman spectroscopic studies of gadolinium trichloride as a function of temperature
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Laser Raman spectrometry is being used in our laboratory to identify the crystal structures of lanthanide and actinide compounds.The phonon Raman spectrum of an ionic, crystalline sample is characteristic of the particular crystal structure(s) exhibited b
- Daniel, J. F.,Wilmarth, W. R.,Begun, G. M.,Peterson, J. R.
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- Hydrothermal assembly of a novel three-dimensional framework formed by [GdMo12O42]9- anions and nine coordinated GdIII cations
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The three-dimensional framework of [Gd(H2O)3]3[GdMo12O42]vdt·3H2O, which was synthesized from hydrothermal reaction, is built up from Silverton-type anions linked by nine coordinated gadolinium(III) cations. It is the first time that the paramagnetic lanthanide(III) cation is introduced into the Silverton-type anionic center in the heteropolymolybdate chemistry, and it acts as 18 dentate ligands coordinating to six GdIII atoms and linking up six other neighboring [Mo12GdO42]9- units in a staggered manner to generate a remarkable three-dimensional framework. The magnetic susceptibility measurement suggests that the weak antiferromagnetic behavior results from the transformation of O-Mo-O units, which has been confirmed by EPR spectra. Copyright
- Wu, Chuan-De,Lu, Can-Zhong,Zhuang, Hong-Hui,Huang, Jin-Shun
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- Pyridine and phosphonate containing ligands for stable lanthanide complexation. An experimental and theoretical study to assess the solution structure
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We report an experimental and theoretical study of the stability and solution structure of lanthanide complexes with two novel ligands containing pyridine units and phosphonate pendant arms on either ethane-1,2-diamine (L 2) or cyclohexane-1,2-diamine (L3) backbones. Potentiometric studies have been carried out to determine the protonation constants of the ligands and the stability constants of the complexes with GdIII and the endogenous metal ions ZnII and Cu II. While the stability constant of the GdL2 complex is too high to be determined by direct pH-potentiometric titrations, the cyclohexyl derivative GdL3 has a lower and assessable stability (logK GdL 3 = 17.62). Due to the presence of the phosphonate groups, various protonated species can be detected up to pH ≈ 8 for both ligands and all metal ions studied. The molecular clusters [Ln(L)(H2O)] 3-·19H2O (Ln = La, Nd, Ho or Lu; L = L2 or L3) were characterized by theoretical calculations at the HF level. Our calculations provide two minimum energy geometries where the ligand adopts different conformations: twist-wrap (tw), in which the ligand wraps around the metal ion by twisting the pyridyl units relative to each other, and twist-fold (tf), where the slight twisting of the pyridyl units is accompanied by an overall folding of the two pyridine units towards one of the phosphonate groups. The relative free energies of the tw and tf conformations of [Ln(L)(H2O)]3- (L = L2, L3) complexes calculated in aqueous solution (C-PCM) by using the B3LYP model indicate that the tw form is the most stable one along the whole lanthanide series for the complexes of L3, while for those of L2 only the GdIII complex is more stable in the tf conformation by ca. 0.5 kcal mol-1. 1H NMR studies of the EuIII complex of L3 show the initial formation of the tf complex in aqueous solution, which slowly converts to the thermodynamically stable tw form. The structures calculated for the NdIII complexes are in reasonably good agreement with the experimental solution structures, as demonstrated by Nd III-induced relaxation rate enhancement effects in the 1H NMR spectra. This journal is The Royal Society of Chemistry.
- Mato-Iglesias, Marta,Balogh, Edina,Platas-Iglesias, Carlos,Toth, Eva,De Blas, Andres,Rodriguez Blas, Teresa
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- ESR of GdF3 and related molecules at 4 K
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The pyramidal (C3ν) GdF3 molecule was trapped in neon and argon matrices at 4 K and its ESR spectrum measured in the X-band region.In neon the spectrum exhibited several off-principal-axis transitions which were sensitive to the assigned magnetic parameters.It was shown to be a S=7/2 molecule (ground state 8A1) with g = 1.995, g = 1.990, and = 0.433 cm-1.The 19F hfs was unresolved and therefore s = + 1/2 - 1/2 transition of GdH3 was observed, yielding = 0.7 to 1.3 cm-1, and it is inferred to be a planar (D3h) molecule (ground state 8A'1).Weak spectra of GdCl3 (8A1) and GdF2 (9A1) were also observed, yielding ca. 0.36 and 0.20 cm-1, respectively.
- Baumann, C. A.,Zee, R. J. Van,Zeringue, K. J.,Weltner, W.
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- Analysis of the conformational behavior and stability of the SAP and TSAP isomers of lanthanide(III) NB-DOTA-type chelates
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Controlling the water exchange kinetics of macrocyclic Gd3+ chelates, a key parameter in the design of improved magnetic resonance imaging (MRI) contrast media, may be facilitated by selecting the coordination geometry of the chelate. The water exchange kinetics of the mono- capped twisted square antiprism (TSAP) being much closer to optimal than those of the mono capped square antiprism (SAP) render the TSAP isomer more desirable for high relaxivity applications. Two systems have been developed that allow for selection of the TSAP coordination geometry in 1,4,7,10-tetraazacyclododecane-1,4,7,10- tetraacetic acid (DOTA)-type Gd3+ chelates, both based upon the macrocycle nitrobenzyl cyclen. In this paper we report investigations into the stability and formation of these chelates. Particular focus is given to the production of two regioisomeric chelates during the chelation reaction. These regioisomers are distinguished by having the nitrobenzyl substituent either on a corner or on the side of the macrocyclic ring. The origin of these two regioisomers appears to stem from a conformation of the ligand in solution in which it is hypothesized that pendant arms lie both above and below the plane of the macrocycle. The conformational changes that then result during the formation of the intermediate H2GdL+ chelate give rise to differing positions of the nitrobenzyl substituent depending upon from which face of the macrocycle the Ln3+ approaches the ligand.
- Tircso, Gyula,Webber, Benjamin C.,Kucera, Benjamin E.,Young, Victor G.,Woods, Mark
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- Extraction of Chlorides of Some Lanthanoides by Tricaprylylmethylammonium Pelargonate
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The extraction of some lanthanoides by tricaprylylmethylammonium pelargonate has been investigated in the system of LnCl3 - Na(H)Cl-R4NB-CCl4 at constant ionic strength μ = 0.1.A mechanism of the extraction process is suggested, which explains the simultaneous extraction of HCl and LnCl3. - Keywords.Binary extraction; Tricaprylylmethylammonium pelargonate; Distribution coefficient; Lanthanoides.
- Georgiev, Georgi,Zakharieva, Maria
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- Synthesis and crystal structure of 1D polyoxometalate-based composite compound, [{Gd(NMP)6}(PMo12O40)]n (NMP = N-methyl-2-pyrrolidone)
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A novel compound, [{Gd(NMP)6}(PMo12O40)]n, has been synthesized and characterized by IR, and UV spectroscopy, and single crystal X-ray structural analysis. It forms an unprecedented one-dimensional zigzag chain built from alternating polyanions and cationic units through Mo-Ot-Gd-Ot-Mo links in the crystal. In the compound, Gd3+ is eight-coordinated with a bicapped trigonal prism geometry environment of oxygen atoms. The results of the single crystal X-ray diffraction analyses and IR are agreement and both show the metal cation units are coordinately bonded to the Keggin cluster. The UV spectrum of the title compound suggests that the compound is entirely dissociated in dilute solution.
- Niua, Jing-Yang,Wei, Mei-Lin,Wang, Jing-Ping,Dang, Dong-Bin
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- SYNTHESIS AND STRUCTURE OF (η5-C5H5)3Gd*OC4H8
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Reaction of a 1/1 mole ratio of GdCl3 and NaC5H5 in THF resulted in the formation of (η5-C5H5)3Gd*THF.The compound crystallizes in the monoclinic space group P21/n with unit cell constants a 8.220(4), b 24.650(9), c 8.317(4) Angstroem, β 101.39(3) deg, and Dc 1.71 g cm-3 for Z = 4.Full-matrix least-squares refinement has led to a final R value of 0.053 based on 2610 independent observed reflections.The THF molecule is coordinated to the gadolinium atom at a Gd-O distance of 2.494(7) Angstroem.The Gd-C(cyclopentadienyl) bond lengths range from 2.68(2) to 2.80(1) Angstroem, and average 2.74(3) Angstroem.
- Rogers, Robin D.,Bynum, R. Vann,Atwood, Jerry L.
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- Extraction methods in development of Gd-loaded liquid organic scintillators for antineutrino detection: 2. Scintillators based on solutions of gadolinium 2-methylvalerate
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Complexes of Gd with carboxylic acids C4-C9 were prepared, and their properties were studied: solubility in water and organic solvents in relation to temperature, melting points, and decomposition points. A procedure was developed for removing water from gadolinium 2-methylvalerate Gd(2MVA)3 to a final content not exceeding 0.01%. To increase the solubility of Gd(2MVA)3 in low-polarity organic solvents and to stabilize the resulting organic solutions, it was suggested to add extractants such as 2-methylvaleric acid (H2MVA) or neutral organophosphorus compounds: triisoamylphosphine oxide (TIAPO) or trioctylphosphine oxide (TOPO). Liquid Gd-loaded organic scintillators based on Gd(2MVA)3 solutions with additions of H2MVA, TIAPO, and TOPO in trimethylbenzene (TMB), phenylxylylethane (PXE), and their mixtures with dodecane were prepared. Long-term tests (up to 2 years) of the stability of the optical properties of the scintillators obtained proved their stability at temperatures of up to 30°C. At elevated temperatures (40°C and higher), the scintillators degrade. The previously made suggestion that water in the scintillator negatively affects its optical properties in prolonged storage was confirm.
- Danilov,Krylov,Tsivadze,Barabanov,Bezrukov,Novikova,Yanovich,Demina,Cattadori,Di Vacri
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- Synthesis, thermal properties and spectroscopic study of solid mandelate of light trivalent lanthanides
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Characterization, thermal stability and thermal decomposition of light trivalent lanthanide mandelates Ln(C6H5CH(OH)CO 2)3·nH2O (Ln = La to Gd, except Pm) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), experimental and theoretical infrared spectroscopy, elemental analysis, X-ray diffractometry, complexometry and TG-DSC coupled to FTIR. The dehydration of the lanthanum, samarium, europium and gadolinium compounds occurs in a single step while for praseodymium and neodymium ones it occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in three, four or five consecutive steps, with formation of the respective oxides CeO2, Pr6O11 and Ln2O3 (Ln = La, Nd to Gd) as final residues. The results also provide information concerning the composition, thermal behavior and gaseous products evolved during the thermal decomposition of these compounds. The theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the lanthanum.
- Gigante,Gomes,Lima,Caires,Treu-Filho,Ionashiro
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- Self-assembled light lanthanide oxalate architecture with controlled morphology, characterization, growing mechanism and optical property
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Flower-like Sm2(C2O4)3· 10H2O had been synthesized by a facile complex agent assisted precipitation method. The flower-like Sm2(C2O 4)3·10H2O was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, thermogravimetry- differential thermal analysis and photoluminescence. The possible growth mechanism of the flower-like Sm2(C2O4) 3·10H2O was proposed. To extend this method, other Ln2(C2O4)3·nH2O (Ln = Gd, Dy, Lu, Y) with different morphologies also had been prepared by adjusting different rare earth precursors. Further studies revealed that besides the reaction conditions and the additive amount of complex agents, the morphologies of the as-synthesised lanthanide oxalates were also determined by the rare earth ions. The Sm2(C2O4) 3·10H2O and Sm2O3 samples exhibited different photoluminescence spectra, which was relevant to Sm 3+ energy level structure of 4f electrons. The method may be applied in the synthesis of other lanthanide compounds, and the work could explore the potential optical materials.
- He, Hongmei,Zhang, Youjin,Zhu, Wei,Zheng, Ao
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p. 1546 - 1552
(2011/10/01)
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- Preparation and characterization of rare earth orthoborates, LnBO 3 (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO3:Gd, Tb, Eu by metathesis reaction: ESR of LaBO3:Gd and luminescence of LaBO3:Tb, Eu
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Lanthanide orthoborates of composition LnBO3 (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO3:Gd, Tb, Eu have been prepared by metathesis reaction. This method provides a convenient route for the synthesis of orthoborates and its solid solutions at low temperatures. Powder X-ray diffraction and FT-IR spectroscopy were used to characterize these borates. Rare earth borates, (LnBO3) are isomorphous with different forms of CaCO3 depending on the radius of rare earth ion. LaBO3, LaBO3:Gd, Tb, Eu, PrBO3, NdBO3 crystallized in aragonite structure, SmBO3 crystallized in H-form and TbBO 3, EuBO3, GdBO3, DyBO3, YBO 3 crystallized in vaterite structure. The structural analysis of TbBO3 was carried out. The morphology of these borates was obtained from Scanning electron microscopy. Spin-Hamiltonian parameters for Gd 3+ are deduced from room temperature electron spin resonance spectrum of LaBO3:Gd. The luminescence of LaBO3:Tb, Eu gave characteristics peaks corresponding to Tb3+, Eu3+ respectively.
- Velchuri, Radha,Kumar, B. Vijaya,Devi, V. Rama,Prasad,Prakash, D. Jaya,Vithal
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p. 1219 - 1226
(2011/07/09)
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- Lanthanide carbonates
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The crystal and molecular structures of the rare earth carbonates with the general formulae [C(NH2)]3 [Ln(CO3)4 (H2O)]·2H2O (where Ln = Pr3+,Nd 3+,Sm3+,Eu3+,Gd3+,Tb 3+)and [C(NH2)]3 [Ln(CO3) 4]·2H2O (where Ln = Y3+,Dy 3+,Ho3+,Er3+, Tm3+,Yb 3+,Lu3+) were determined. The crystals consist of monomeric [Ln(CO3)4 (H2O)] 5-or [Ln(CO3)4] 5-complex anions in which the carbonate ligands coordinate to the Ln3+ion in a bidentate manner. The spectroscopic (UV/Vis/NIR and IR) properties of the crystalline lanthanide carbonates, as well as their aqueous solutions, were determined. Correlation between the spectroscopic and the structural data enabled us to conclude that the [Ln(CO3)4 (OH)]6-and [Ln-(CO 3)4]5- species predominate in the light and heavy lanthanide solutions, respectively. The nature of the Ln-O interaction was also discussed. The experimental data, as well as the theoretical calculations, indicated that the Ln-O(CO3 2-) bond is more covalent than the Ln-O(OH2) bond. Moreover, the covalency degree is larger for the heavy lanthanide ions. Inspection of the NBO results revealed that the oxygen hybrids, with the approximate composition sp4, form strongly polarized bonds with the 6s6p5d4 hybrids of lutetium. 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
- Janicki, Rafal,Starynowicz, Przemyslaw,Mondry, Anna
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p. 3601 - 3616
(2011/10/11)
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- Synthesis and luminescent properties of gadolinium aluminates phosphors
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In this work, aluminum-gadolinium oxides with different phases were prepared by the non-hydrolytic sol-gel route, using lower temperatures than those employed in methods such as solid-state reaction and Pechini method. The influence of heating treatment on sample structure was investigated. The formation process and the local structure of the samples are discussed on the basis of thermal, X-ray diffraction, photoluminescence (PL) spectroscopy, and infrared spectroscopy analyses. The quantum efficiency of Eu3+ in the different phases obtained in this studied was evaluated. Initial crystallization and the GdAlO3 phase were observed at temperatures around 400 °C. PL data of all the samples revealed the characteristic transition bands arising from the 5D0 → 5FJ (J = 0, 1, 2, 3, and 4) manifolds under maximum excitation at 275, 393, and 467 nm in all cases. The 5D0 → 7F2 transition often dominates the emission spectra, indicating that the Eu3+ ion occupies a site without inversion center.
- Matos, Marcela G.,Calefi, Paulo S.,Ciuffi, Katia J.,Nassar, Eduardo J.
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- Synthesis, characterization and thermal behaviour of light trivalent lanthanides folates on solid state
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Solid state Ln2-L3 compounds, where Ln stands for light trivalent lanthanides (lanthanum to gadolinium), except promethium, and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG coupled to FTIR, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the stoichiometry, crystallinity, ligand's denticity, thermal stability, thermal behaviour and identification of the gaseous products evolved during the thermal decomposition of these compounds.
- Dametto, P. R.,Caires, F. J.,Ambrozini, B.,Ionashiro, M.
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p. 831 - 836
(2011/11/04)
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- Comparison of covalency in the lanthanide chloride and nitrate complexes based on the adsorption data on zeolite y
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The changes of the distribution constants Kd of lanthanide chlorides in the system: zeolite Y (solid phase)-sodium chloride (aqueous phase) were investigated. The evident tetrad effect in the change of log Kd values within the lantha
- G?adysz-P?aska, Agnieszka,Majdan, Marek,Ferenc, Wies?awa,Sarzyński, Jan
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p. 469 - 474
(2012/03/22)
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- Structural characterization of methanol substituted lanthanum halides
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The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75·5.25(MeOH)]+0.25 [LaBr3.25·4.75(MeOH)]-0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(μ-Cl)]2 (6) and [La(MeOH)9](I)3·MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4-6 were slightly higher in comparison to their hydrated counterparts.
- Boyle, Timothy J.,Ottley, Leigh Anna M.,Alam, Todd M.,Rodriguez, Mark A.,Yang, Pin,Mcintyre, Sarah K.
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p. 1784 - 1795
(2010/07/03)
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- Synthesis, characterization and thermal behaviour of solid-state compounds of light trivalent lanthanide succinates
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Characterization, thermal stability and thermal decomposition of light trivalent lanthanide succinates, Ln2(C4H4O4)3 ·nH2O (Ln = La to Gd, except Pm) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry. The dehydration of the lanthanum and cerium compounds occurs in a single step, while for the praseodymium to gadolinium compounds the dehydration occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in consecutive and/or overlapping steps, except for the cerium compound, with formation of the respective oxides, CeO2, Pr6O11 and Ln2O3 (Ln = La, Nd to Gd), as final residue. The results also provided information concerning the denticity of the ligand and thermal behaviour of these compounds.
- Lima,Caires,Carvalho,Siqueira,Ionashiro
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- Electrodeposition of RE-TM (RE = La, Sm, Gd; TM = Fe, Co, Ni) films and magnetic properties in urea melt
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Rare earth (RE)-3d transition metal (TM) films were codeposited in low temperature urea-acetamide-NaBr-KBr-RECl3-TMCl2 baths by potentiostatic electrolysis. Cyclic voltammetry is used to investigate the electrochemical behavior of RE
- Li, Jiaxin,Lai, Heng,Fan, Biqiang,Zhuang, Bin,Guan, Lunhui,Huang, Zhigao
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p. 547 - 551
(2009/10/30)
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- Synthesis, characterization and thermal behavior on solid tartrates of light trivalent lanthanides
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Solid state Ln-L compounds, where Ln stands for light trivalent lanthanides (L-Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry,
- Ambrozini,Dametto,Siqueira,Carvalho,Ionashiro
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p. 761 - 764
(2010/01/05)
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- Near-infrared luminescent xerogel materials covalently bonded with ternary lanthanide [Er(III), Nd(III), Yb(III), Sm(III)] complexes
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A β-diketone ligand 4,4,5,5,5-pentafluoro-1-(2-naphthyl)-1,3- butanedione (Hpfnp), which contains a pentafluoroalkyl chain, was synthesized as the main sensitizer for synthesizing new near-infrared (NIR) luminescent Ln(pfnp)3phen (phen = 1,10-p
- Feng, Jing,Yu, Jiang-Bo,Song, Shu-Yan,Sun, Li-Ning,Fan, Wei-Qiang,Guo, Xian-Min,Dang, Song,Zhang, Hong-Jie
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p. 2406 - 2414
(2009/06/28)
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- Macrocyclic receptor exhibiting unprecedented selectivity for light lanthanides
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We report a new macrocyclic ligand, N,N'-bis[(6-carboxy-2-pyridil)methyl]- 4,13-diaza-18-crown- 6 (H2bp18c6), designed for complexation of lanthanide ions in aqueous solution. Potentiometric measurements evidence an unprecedented selectivity of bp18c6 for the large LnIIIions. Among the different LnIII ions, LaIII and CeIII show the highest log KML values, with a dramatic drop of the stability observed from CeIII to LuIII asthe ionic radius of the LnIII ions decreases (log Cel- log KLul ) 6.9). The X-ray crystal structures of the GdIII and YbIII complexes show that the metal ion is directly bound to the10 donor atoms of the bp18c6 ligand. The structure of the complexes in solution has been investigated by 1H and 13C NMR spectroscopy, as well a s by theoretical calculations performed at the DFT (B3LYP) level. Our results indicate that a conformational change occurs around the middle of the lanthanide series: for the larger LnIII ions the most stable conformation is Δ( δ λδ)( δ λδ), while for the smallest LnIII ions (Gd-Lu) our calculations predict the Δ(λδ λ)( λδ λ form being the most stable one. This structural change was confirmed by the analysis of the Ce III-, PrIII-, and YbIII-induced paramagnetic 1H shifts. The selectivity that bp18c6 shows for the large LnIII ions can be attributed to a better fit between the light LnIII ions and the relatively large crown fragment of the ligand. Indeed, our DFT calculations indicate that the interaction between the LnIII ion and several donor atoms of the crown moiety is weakened as the ionic radius of the metal ion decreases.
- Roca-Sabio, Adrian,Mato-Iglesias, Marta,Esteban-Gomez, David,Toth, Eva,Blas, Andres de,et al.
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p. 3331 - 3341
(2009/07/30)
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- Synthesis, characterization and thermal behaviour of solid-state compounds of europium(III) and gadolinium(III) 3-methoxybenzoate
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Solid-state Ln-C8H7O3 compounds, where Ln stands for Eu(III) and Gd(III) and C8H7O3 is 3-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry and differential thermal analy
- Dametto, Patricia R.,Ambrozini, Beatriz,Siqueira, Adriano B.,Carvalho, Claudio T.,Ionashiro, Massao
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p. 765 - 768
(2010/01/06)
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- Stability, water exchange, and anion binding studies on lanthanide(III) complexes with a macrocyclic ligand based on 1.7-diaza-12-crown-4: Extremely fast water exchange on the Gd3+ complex
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The picolinate-derivative ligand based on the 1,7-diaza-12-crown-4 platform (bp12c4 2-) forms stable Ln3+ complexes with stability constants increasing from the early to the middle lanthanides, then being relatively constant for the
- Palinkas, Zoltan,Roca-Sabio, Adrian,Mato-lglesias, Marta,Esteban-Gomez, David,Platas-Iglesias, Carlos,De Blas, Andres,Rodriguez-Blas, Teresa,Toth, Eva
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p. 8878 - 8889
(2009/12/25)
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- A benzene-core trinuclear GdIII complex: Towards the optimization of relaxivity for MRI contrast agent applications at high magnetic field
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A novel ligand, H12L, based on a trimethylbenzene core bearing three methylenediethylenetriamine-N,N,N″,N″-tetraacetate moieties (-CH2DTTA4-) for Gd3+ chelation has been synthesized, and its trinuclear Gd3+ complex [Gd3L(H 2O)6]3- investigated with respect to MRI contrast agent applications. A multiple-field, variable-temperature 17O NMR and proton relaxivity study on [Gd3L(H 2O)6]3- yielded the parameters characterizing water exchange and rotational dynamics. On the basis of the 17O chemical shifts, bishydration of Gd3+ could be evidenced. The water exchange rate, kex298 = 9.0 ± 3.0 s-1 is around twice as high as kex298 of the commercial [Gd(DTPA)(H2O)]2- and comparable to those on analogous Gd3+-DTTA chelates. Despite the relatively small size of the complex, the rotational dynamics had to be described with the Lipari-Szabo approach, by separating global and local motions. The difference between the local and global rotational correlation times, τlO298 = 170 ± 10 ps and τgO298 = 540 ± 100 ps respectively, shows that [Gd3L(H2O)6]3- is not fully rigid; its flexibility originates from the CH2 linker between the benzene core and the poly(amino carboxylate) moiety. As a consequence of the two inner-sphere water molecules per Gd3+, their close to optimal exchange rate and the appropriate size and limited flexibility of the molecule, [Gd3L(H2O)6]3- has remarkable proton relaxivities when compared with commercial contrast agents, particularly at high magnetic fields (r1 = 21.6, 17.0 and 10.7 mM-1s -1 at 60, 200 and 400 MHz respectively, at 25 °C; r1 is the paramagnetic enhancement of the longitudinal water proton relaxation rate, referred to 1 mM concentration of Gd3+). The Royal Society of Chemistry.
- Livramento, Joao Bruno,Helm, Lothar,Sour, Angelique,O'Neil, Conlin,Merbach, Andre E.,Toth, Eva
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p. 1195 - 1202
(2008/09/18)
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- Energy transfer from Gd3+ to Tb3+ in solution
-
The use of the 4f7 ion Gd3+ as an energy transfer donor in solution is reported for the first time. The luminescence from the 6P multiplet term of Gd3+ in chloride solution is quenched not only by increasing concentration, but also by the addition of Tb3+. The energy transfer from Gd3+ to Tb3+ in solution has been followed by selective decay measurements and the energy transfer constant shows a linear relationship with Tb3+ concentration up to ~0.05 M, after which value saturation is reached. The Tb3+ acceptor 5D4 emission intensity as a function of time is well-modeled.
- Tanner, Peter A.,Wang, Jiwei
-
p. 335 - 338
(2009/02/01)
-
- 2-Methoxybenzylidenepyruvatewith heavier trivalent lanthanides and yttrium(III): Synthesis and characterization
-
Solid-state Ln(2-MeO-BP) compounds, where Ln stands for trivalent Eu to Lu and Y(III) and 2-MeO-BP (which is 2-methoxybenzylidenepyruvate) have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanni
- Ionashiro,Bannach,Siqueira,De Carvalho,Rodrigues,Ionashiro
-
p. 953 - 959
(2009/02/01)
-
- Solubility behavior of rare earths with ammonium carbonate and ammonium carbonate plus ammonium hydroxide: Precipitation of their peroxicarbonates
-
The purpose of this work is to report the significant behavior of the rare earths when treated with ammonium carbonate and with a binary mixture of ammonium carbonate plus ammonium hydroxide. The carbonates of some rare earths are completely soluble in ammonium carbonate or in ammonium carbonate plus ammonium hydroxide, while others are only partially soluble and finally some are completely insoluble. Addition of hydrogen peroxide to the soluble complexed rare earth carbonates results in the precipitation of a series of a new compounds described as rare earth peroxicarbonates. The rare earths have some different precipitation behavior in the carbonate-peroxide system. Some are completely and immediately precipitated, others are completely precipitated after an aging period, and finally other are not precipitated at all. These different behaviors open a new possibility for the separation chemistry of the rare earths. Sm, Gd, Dy, Y, Yb and Tm are fast and completely soluble in ammonium carbonate. Ho, Eu and Tb are completely soluble in ammonium carbonate but slowly dissolved. La, Ce, Pr and Nd are only partially soluble in ammonium carbonate. While Ce, Pr, Nd, Sm, Eu and Dy are completely and easily soluble in the ammonium carbonate plus ammonium hydroxide mixture, La is only partially soluble and Tb is completely insoluble in the same mixture. Concerning the peroxicarbonates, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy and Ho are quantitatively precipitated. The precipitation of the Er peroxicarbonate is quantitative, but after an aging period of 24 h. Y is not precipitated at all. The process is very easy, simple and economically attractive. Although proved in bench scale, its scale-up is easily feasible.
- de Vasconcellos, Mari E.,da Rocha,Pedreira,Queiroz, Carlos A. da S.,Abr?o, Alcídio
-
p. 426 - 428
(2008/10/09)
-
- Synthesis, characterization and thermal behaviour of solid 2-methoxybenzoates of trivalent metals
-
Solid-state Ln(L)3 compounds, where Ln stands for trivalent Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y and L is 2-methoxybenzoate have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanni
- Siqueira,Carvalho,Ionashiro,Bannach,Rodrigues,Ionashiro
-
p. 945 - 951
(2009/02/01)
-
- Synthesis, potentiometric, kinetic, and NMR studies of 1,4,7,10- tetraazacyclododecane-1,7-bis(acetic acid)-4,10-bis(methylenephosphonic acid) (DO2A2P) and its complexes with Ca(II), Cu(II), Zn(II) and lanthanide(III) ions
-
A cyclen-based ligand containing trans-acetate and trans- methylenephosphonate pendant groups, H6DO2A2P, was synthesized and its protonation constants (12.6, 11.43, 5.95, 6.15, 2.88, and 2.77) were determined by pH-potentiometry and 1H NMR spectroscopy. The first two protonations were shown to occur at the two macrocyclic ring N-CH 2-PO32- nitrogens while the third and fourth protonations occur at the two phosphonate groups. In parallel with protonation of the two -PO32- groups, the protons from the NH +-CH2-PO32- are transferred to the N-CH2-COO- nitrogens. The stability constants of the Ca2+, Cu2+, and Zn2+ (ML, MHL, MH2L, and M2L) complexes were determined by direct pH-potentiometry. Lanthanide(III) ions (Ln3+) form similar species, but the formation of complexes is slow; so, out-of-cell pH-potentiometry (La 3+, Eu3+, Gd3+, Y3+) and competitive spectrophotometry with Cu(II) ion (Lu3+) were used to determine the stability constants. By comparing the log KML values with those of the corresponding DOTA (H4DOTA = 1,4,7,10-tetraazacyclododecane-1,4, 7,10-tetraacetic acid) and DOTP (H8DOTP = 1,4,7,10- tetraazacyclododecane-1,4,7,10-tetramethylenephosphonic acid) complexes, the order DOTA 2+ complexes, for which the order is reversed. The relaxivity of Gd(DO2A2P) decreases between pH 2 and 7 but remains constant in the pH range of 7 1 = 3.6 mM-1 s-1). The linewiths of the 17O NMR signals of water in the absence and presence of Gd(DO2A2P) (at pH = 3.45 and 8.5) between 274 and 350 K are practically the same, characteristic of a q = 0 complex. Detailed kinetic studies of the Ce3+ and Gd3+ complexes with DO2A2P showed that complex formation is slow and involves a high stability diprotonated intermediate Ln(H2DO2A2P)*. Rearrangement of the diprotonated intermediate into the final complex is an OH- assisted process but, unlike formation of Ln(DOTA) complexes, rearrangement of Ln(H2DO2A2P)* also takes place spontaneously likely as a result of transfer of one of the protons from a ring nitrogen to a phosphonate group. The order of the OH- assisted formation rates of complexes is DOTA > DO2A2P > DOTP while the order of the proton assisted dissociation rates of the Gd3+ complexes is reversed, DOTP > DO2A2P > DOTA. 1H and 13C NMR spectra of Eu(DO2A2P) and Lu(DO2A2P) were assigned using two-dimensional correlation spectroscopy (2D COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear chemical shift correlation (HETCOR), and exchange spectroscopy (EXSY) NMR methods. Two sets of 1H NMR signals were observed for Eu(DO2A2P) characteristic of the presence of two coordination isomers in solution, a twisted square antiprism (TSAP) and a square antiprism (SAP), in the ratio of 93% and 7%, respectively. Line shape analysis of the 1H NMR spectra of Lu(DO2A2P) gave lower activation parameters compared to La(DOTP) for interconversion between coordination isomers. This indicates that the Ln(DO2A2P) complexes are less rigid probably due to the different size and spatial requirements of the carboxylate and phosphonate groups.
- Kalman, Ferenc K.,Baranyai, Zsolt,Toth, Imre,Banyai, Istvan,Kiraly, Robert,Bruecher, Ernoe,Aime, Silvio,Sun, Xiankai,Sherry, A. Dean,Kovacs, Zoltan
-
p. 3851 - 3862
(2009/02/02)
-
- Comparison of thermal properties of lanthanide trimellitates prepared by different methods
-
By diffusion in gel medium new complexes of formulae: Nd(btc) ·6H2O, Gd(btc)·4.5H2O and Er(btc)?5H2O (where btc=(C6H3(COO)33-) were obtained. Isomorphous compounds were crystallized in the
- Lyszczek, Renata
-
p. 833 - 838
(2009/02/07)
-
- A systemic study of stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by alkaline chlorides as complex former
-
A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by the vapor complexes KLnCl4 and NaLnCl4 (Ln = Sc, Y and La-Lu) used NaCl and KCl as complex former, respectively. The results showed that the SC-CVT characteristics are similarly for NaCl and KCl as complex former, the main deposition temperature of the rare earth chlorides LnCl3 is in the increasing order ScCl3 3 3, and then with a systematically decreasing trend from the early lanthanide chlorides to the end one. The results also showed that the total transported amount of the produced chlorides is YCl3 > ScCl3, and they are much higher than that of most lanthanoid chlorides. For lanthanoids, the total transported amount of chloride increases systematically from the early lanthanoid chlorides to the end one except for EuCl3 and GdCl3 mediated by KCl and NaCl as complex former, respectively, which showed the divergence effect of Gd in the total transport efficiency. But there are some differences in SC-CVT characteristics of pure rare earth oxide mediated by KCl and NaCl as complex former, that is the main deposition temperature region for the same rare earth element was lower for KCl than that for NaCl as complex former except for LaCl3, CeCl3, YbCl3 and LuCl3, while the total transport amount of rare earth chloride for KCl as complex former is higher than that for NaCl except for LaCl3 and EuCl3. More over, the discussion was carried out for Sc and Y on the one hand and the lanthanides contain 4f electron as another hand based on the 4f electron hybridization assumption. Further more, the transport characteristics of rare earth oxides with alkaline chlorides as complex former in this study were compared to that with AlCl3 as complex former.
- Sun, Yan-Hui,He, Peng,Chen, Hua-Ni
-
p. 352 - 358
(2008/10/09)
-
- Microcalorimetric studies on the interactions of lanthanide ions with bovine serum albumin
-
The interactions of lanthanide ions (Ln3+) with bovine serum albumin (BSA) under mimetic physiological conditions (310.15 K, pH 6.7, 0.1MNaCl) were studied by microcalorimetry. For the first time, based on Two Sets of Independent Sites Model, m
- Li,Wang,Li,Wang
-
p. 899 - 905
(2008/10/09)
-
- Synthesis, characterization and thermal behaviour of solid-state compounds of yttrium and lanthanide benzoates
-
Solid-state Ln(Bz)3?H2O compounds where Ln stands for trivalent yttrium or lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffractometry, infra
- Locatelli,Rodrigues,Siqueira,Ionashiro,Bannach,Ionashiro
-
p. 737 - 746
(2008/10/09)
-
- Thermal and spectroscopic investigations of new lanthanide complexes with 1,2,4-benzenetricarboxylic acid
-
The new 1,2,4-benzenetricarboxylates of lanthanide(III) of the formula Ln(btc)?nH2O, where btc is 1,2,4-benzenetricarboxylate; Ln is La-Lu, and n=2 for Ce; n=3 for La, Yb, Lu; and n=4 for Pr-Tm were prepared and characterized by elemental analy
- Lyszczek
-
p. 533 - 539
(2008/10/09)
-
- Luminescence and structural properties of lanthanide complexes of Schiff bases derived from pyridoxal and amino acids
-
Lanthanide complexes of Schiff bases (SBs) with 1: 1 and 1: 2 (M: Lig) stoichiometric ratios were prepared by condensation of pyridoxal (PL) and aspartic acid (Asp) or l-histidine (His), respectively, in the presence of the appropriate metal chloride as a templating agent. These complexes were studied by optical spectroscopy and single crystal X-ray diffraction techniques. Crystallographic studies of 1: 1 ([Eu(PL-Asp)(H2O) 4](H2O)) and 1: 2 ([Eu(PL-His)2(H 2O)2]Cl(H2O)4) complexes show that EuIII is eight-coordinate in both structures, in a distorted square antiprism environment formed by the phenolic oxygen of PL, the nitrogen atom of carbon-nitrogen double bond, oxygen atoms of the carboxylate groups of His or Asp, and oxygen atoms of the water molecules. The main species formed in aqueous solutions containing these SBs have been determined by analysis of the luminescence spectra, lifetimes of EuIII excited states and vibronic interaction as well as structural features of the EuIII coordination sphere. Possible tetradentate coordination function of SBs in aqueous solutions with relatively high concentrations as well as the potential application of the lanthanide SB complexes as new luminescence materials are discussed. The Royal Society of Chemistry.
- Puntus, Lada,Zhuravlev, Konstantin,Lyssenko, Konstantin,Antipin, Mikhail,Pekareva, Irina
-
p. 4079 - 4088
(2008/03/12)
-
- Phosphinic derivative of DTPA conjugated to a G5 PAMAM dendrimer: An 17O and 1H relaxation study of its Gd(III) complex
-
A DTPA-based chelate containing one phosphinate group was conjugated to a generation 5 polyamidoamine (PAMAM) dendrimer via a benzylthiourea linkage. The Gd(iii) complex of this novel conjugate has potential as a contrast agent for magnetic resonance imaging (MRI). The chelates bind Gd3+ via three nitrogen atoms, four carboxylates and one phosphinate oxygen, and one water molecule completes the inner coordination sphere. The monomer Gd(iii) chelates bearing nitrobenzyl and aminobenzyl groups ([Gd(DTTAP-bz-NO2)(H 2O)]2- and [Gd(DTTAP-bz-NH2)(H 2O)]2-) as well as the dendrimeric Gd(iii) complex G5-(Gd(DTTAP))63) were studied by multiple-field, variable temperature 17O and 1H NMR. The rate of water exchange is faster than that of [Gd(DTPA)(H2O)]2- and very similar on the two monomeric complexes (8.9 and 8.3 × 106 s-1 for [Gd(DTTAP-bz-NO2)(H2O)]2- and [Gd(DTTAP-bz-NH2)(H2O)]2-, respectively), while it is decreased on the dendrimeric conjugate (5.0 × 106 s -1). The Gd(iii) complex of the dendrimer conjugate has a relaxivity of 26.8 mM-1 s-1 at 37 °C and 0.47 T (corresponding to 1H Larmor frequency of 20 MHz). Given the contribution of the second sphere water molecules to the overall relaxivity, this value is slightly higher than those reported for similar size dendrimers. The experimental 17O and 1H NMR data were fitted to the Solomon-Bloembergen-Morgan equations extended with a contribution from second coordination sphere water molecules. The rotational dynamics of the dendrimeric conjugate was described in terms of global and local motions with the Lipari-Szabo approach. The Royal Society of Chemistry 2006.
- Lebdukova, Petra,Sour, Angelique,Helm, Lothar,Toth, Eva,Kotek, Jan,Luke, Ivan,Merbach, Andre E.
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p. 3399 - 3406
(2007/10/03)
-
- Synthesis, characterization and thermal behaviour of solid 4-methoxybenzoates of heavier trivalent lanthanides
-
Solid-state Ln-4-MeO-Bz compounds, where Ln stands for trivalent Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y and 4-MeO-Bz is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scan
- Rodrigues, Emanuel C.,Siqueira, Adriano B.,Ionashiro, Elias Y.,Bannach, Gilbert,Ionashiro, Massao
-
p. 149 - 155
(2008/10/09)
-
- Synthesis, characterization and thermal studies on solid compounds of 2-chlorobenzylidenepyruvate of heavier trivalent lanthanides and yttrium(III)
-
Solid-state compounds of general formula LnL3· nH 2O, where Ln represents heavier lanthanides and yttrium and L is 2-chlorobenzylidenepyruvate, have been synthesized. Chemical analysis, simultaneous thermogravimetry-differential anal
- Bannach,Schnitzler,Treu Filho,Utuni,Ionashiro
-
p. 233 - 240
(2008/10/09)
-
- Equilibria and structure of the lanthanide(III)-2-hydroxy-1,3- diaminopropane-N,N,N′,N′-tetraacetate complexes: Formation of alkoxo-bridged dimers in solid state and solution
-
The complex formed between 1,3-diamino-2-hydroxypropane-N,N,N′, N′-tetraacetic acid (H4L-OH) and Nd3+ at pH 7.5 was found to be a dinuclear dimer in the solid state by X-ray crystallography. In the complex K4[Nd2(L-O)2-(H2O) 2]-14H2O each ligand is coordinated to both Nd 3+ atoms with an iminodiacetate group (the Nd3+-Nd 3+ distance is 3.9283(8) A). The alcoholic OH groups are deprotonated, and the alkoxo oxygens are coordinated to both Nd3+ in a bridging position. The Nd3+ ions are nine-coordinated with one water molecule per Nd(III) ion in the inner sphere. The complex K 4[Nd2(L-O)2(H2O)2] ·14H2O has an inversion center, and the space group is P1. Two of the K+ counterions are six-coordinated, while the other two K+ ions are eight-coordinated; polar polymeric water-K+ layers are formed between the apolar ligand layers via the bridging water molecules. The dinuclear dimer complexes are also present in aqueous solution. The proton relaxivities of the Gd3+ complex decrease with the increase of pH, and at pH > 6, the low relaxivity values indicate the probable absence of H2O in the inner sphere and the predominance of the eight-coordinated dimer species [Gd2(L-O)2]. 4- The results of ESI-TOF MS studies of the complexes of La 3+, Nd3+, and Lu3+ proved the formation of dinuclear dimers in dilute (0.25 mM) solutions. pH-potentiometric titrations indicate the formation of complexes with 1:1 (Ln(L-OH)-, Ln(HL-OH), and Ln2(L-O)24-) and 2:1 (Ln 2(L-O)+) metal-to-ligand ratios. The stability constants of the Ln(L-OH)- species increase from La3+ (log K = 10.19) to Lu3+ (log K = 14.08). The alcoholic OH group of the Ln(L-OH)- species dissociates at unusually low pH values. The pH range of dissociation shifts to lower and lower pH's with the increasing atomic number of the lanthanides. This pH range is about 4-7 for the La3+ complex and 1-4 for the Lu3+ complex. The results of 1D and 2D 1H and 13C NMR studies of the La3+ complex, the number and multiplicity of signals, and the values of coupling constants are in agreement with the dinuclear dimer structure of the complex in solution.
- Tircso, Gyula,Benyei, Attila,Bruecher, Erno,Kis, Anita,Kiraly, Robert
-
p. 4951 - 4962
(2008/10/09)
-
- Synthesis, characterization, thermal stability, reactivity, and antimicrobial properties of some novel lanthanide(III) complexes of 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene
-
Two series of new lanthanide(III) complexes of the type [Ln(HSAT) 2(H2O)3Cl3] and [Ln(HSAT) 2(NO3)3], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy, Tm, Yb, or Lu, and HSAT = 2-(N-salicy
- Mohanan,Devi
-
p. 600 - 609
(2008/10/09)
-
- Comparative study of the mutual separation characteristics for binary mixed oxides Er2O3-Ln2O3 (Ln = Sc, Y, La, Nd, Sm, Gd and Ho) mediated by vapor complexes KLnCl4
-
Mutual separation characteristics for a series of rare earth elements Sc, Y, La, Nd, Sm, Gd, Ho and Er from their binary oxide mixtures Er 2O3-Sc2O3, Er2O 3-Y2O3, Er2O3-La 2O3, Er2O3-Nd2O 3, Er2O3-Sm2O3, Er 2O3-Gd2O3 and Er2O 3-Ho2O3 has been investigated using a stepwise chlorination-chemical vapor transport (SC-CVT) reaction mediated by vapor complexes KLnCl4. The total transported yield of the chlorides produced from the oxide mixtures was in the order of ErCl3 > ScCl3, ErCl3 > YCl3, ErCl3 > LaCl3, ErCl3 > NdCl3, ErCl3 > SmCl3, ErCl3 > GdCl3 and HoCl3 > ErCl3, and the total separation factors are 13.0 for Er:Sc, 1.49 for Er:Y, 1.48 for Er:La, 1.15 for Er:Nd, 2.33 for Er:Sm, 2.72 for Er:Gd and 1.10 for Ho:Er. The largest separation factors 1213.8 for Er:Sc, 6.37 for Er:Y, 189.3 for Er:La, 100.6 for Er:Nd, 105.7 for Er:Sm, 27.8 for Er:Gd and 1.14 for Er:Ho in the lower temperature region, while 102.7 for La:Er, only 14.3 for Nd:Er, 16.7 for Sm:Er, 4.0 for Gd:Er and 2.04 for Ho:Er in the higher temperature region were observed, respectively. The results showed the obvious divergence effect of Gd both in the largest separation factors, the total separation factors and total transport efficiency. Furthermore, the results were discussed on the difference of ionic radius of Sc and Y on the one side and the lanthanoid elements of La, Nd, Sm, Gd, Ho and Er on the other hand, and verified that the ionic radius is one of the decisive factors only for lanthanide elements, not for Sc and Y.
- Sun, Yan-Hui,Chen, Zhen-Fei,Hu, Sheng-Liang
-
p. 175 - 180
(2008/10/09)
-
- Kinetics of formation and dissociation of lanthanide(III) complexes with the 13-membered macrocyclic ligand TRITA
-
The tetraazamacrocyclic ligand TRITA4- is intermediate in size between the widely studied and medically used 12-membered DOTA4- and the 14-membered TETA4-. The kinetic inertness of GdTRITA- was characterized by the rates of exchange reactions with Zn2+ and Eu3+. In the Zn2+ exchange, a second order [H+] dependence was found for the pseudo-first-order rate constant (k0 = (4.2 ± 0.5) × 10-7 s-1; k′ = (3.5 ± 0.3) × 10-1 M-1S-1, k″ = (1.4 ±0.4) × 103 M-2s-1)- In the Eu3+ exchange, at pH 2+ species. At physiological pH, the kinetic inertness of GdTRITA- is considerably lower than that of GdDOTA- (t1/2 = 444 h (25°C) vs. 3.8 × 105 h (37°C), respectively). However, GdTRITA - is still kinetically more inert than GdDTPA2-, the most commonly used MRI contrast agent (t1/2 = 127 h). The formation reactions of LnTRITA- complexes (Ln = Ce, Gd and Yb) proceed via the rapid formation of a diprotonated intermediate and its subsequent deprotonation and rearrangement in a slow, OH- catalyzed process. The stability of the LnH2TRITA* intermediates (log KLnH2L* = 3.1-3.9) is lower than that of the DOTA-analogues. The rate constants of the OH- catalyzed step increase with decreasing lanthanide ion size, and are about twice as high as for DOTA-complexes. The Royal Society of Chemistry 2005.
- Balogh, Edina,Tripier, Raphael,Ruloff, Robert,Toth, Eva
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p. 1058 - 1065
(2007/10/03)
-
- Extraction of lanthanide chlorides by binary extractants based on phosphinic acid derivatives
-
The extraction of lanthanide chlorides by methyltrioctylammonium dialkylphosphinate, dialkyl-monothiophosphinate, or dialkyldithiophosphinate in toluene was studied. In all cases, extractable MA3 compounds were formed in an organic phase. The extractability of metals increased in the order La a considerable effect on the distribution of the lanthanide salts. The extraction capacity of the binary extradants toward lanthanum chloride decreased in the order methyltrioctylammonium dialkylphosphinate > methyltrioctylammonium dialkylmonothiophosphinate > methyltrioctylammonium dialkyldithiophosphinate. Copyright
- Egorova,Belova,Voshkin,Zhilov,Khol'kin
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p. 1781 - 1784
(2008/10/09)
-
- Synthesis, characterization, and luminescence properties of the ternary europium complex covalently bonded to mesoporous SBA-15
-
A novel mesoporous SBA-15 type of hybrid material (phen-SBA-15) covalently bonded with 1, 10-phenanthroline (phen) ligand was synthesized by co-condensation of tetraethoxysilane (TEOS) and the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) in the presence of Pluronic P123 surfactant as a template. The preservation of the chelate ligand structure during the hydrothermal synthesis and the surfactant extraction process was confirmed by Fourier transform infrared (FTIR) and 29Si MAS NMR spectroscopies. SBA-15 consisting of the highly luminescent ternary complex Eu(TTA)3phen (TTA = 2-thenoyltrifluoroacetone) covalently bonded to a silica-based network, which was designated as Eu-(TTA)3phen-SBA-15, was obtained by introducing the Eu(TTA) 3?·2H2O complex into the hybrid materials via a ligand exchange reaction. XRD, TEM, and N2 adsorption measurements were employed to characterize the mesostructure of Eu(TTA)3phen-SBA- 15. For comparison, SBA-15 doped with Eu(TTA)3?·2H2O and Eu(TTA)3phen complexes and SBA-15 covalently bonded with a binary europium complex with phen ligand were also synthesized, and were named SBA-15/Eu(TTA)3, SBA-15/Eu(TTA)3phen, and Eu-phen-SBA-15, respectively. The detailed luminescence studies on all the materials showed that, compared with the doping sample SBA-15/Eu(TTA)3phen and binary europium complex functionalized sample Eu-phen-SBA-15, the Eu(TTA) 3phen-SBA-15 mesoporous hybrid material exhibited higher luminescence intensity and emission quantum efficiency. Thermogravimetric analysis on Eu(TTA)3phen-SBA-15 demonstrated that the thermal stability of the lanthanide complex was evidently improved as it was covalently bonded to the mesoporous SBA-15 matrix. ? 2005 American Chemical Society.
- Peng, Chunyun,Zhang, Hongjie,Yu, Jiangbo,Meng, Qingguo,Fu, Lianshe,Li, Huanrong,Sun, Lining,Guo, Xianmin
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p. 15278 - 15287
(2008/10/09)
-
- Fullerides: Heterometallic superconductors with composition M2M′C60 (M = K, Rb; M′ = Yb, Lu, Sc)
-
One- or two-step reactions of potassium and rubidium fullerides with composition Mk C60 (M = K, Rb; k = 3-6) and K 6C60 + m K mixtures (m = 1, 3) with anhydrous salts M′Cl3 (M′ = La, Pr, Nd, Sm, Gd, Tb, Yb, Lu, Y, Sc) and YbI2 in a toluene-THF medium afforded heterometallic fullerides M3- n M′n C60 (n = 1-3). Among these compounds, substituted fullerides with composition M2M′C60 (M′ = Yb, Lu, Sc) display superconducting properties with critical temperatures of 14-20 K.
- Bulychev,Lunin,Kul'bachinskii,Shpanchenko,Privalov
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p. 1686 - 1692
(2007/10/03)
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- Effect of solid matrices on the luminescence of europium(III) tungstate
-
The effect of natural and synthetic zeolites, CaCO3, and crystalline zirconium phosphate on the luminescence intensity of europium tungstate sorbates was studied in comparison to europium(III)-doped Mg, Ca, Sr, Ba, La, Gd, and Y tungstates prepared by coprecipitation with tungstate anion. The effects of the alkaline-earth cation, metal salt anion, coprecipitation conditions, and calcination temperature on the luminescence were revealed. X-ray powder diffraction showed that the resulting compounds have a scheelite structure. The luminescence intensity of Eu(III)-doped Ca tungstate under the identical conditions of short-wave excitation (λex = 254 nm) makes up 33% of the intensity exhibited by the commercial FL-612 red-emitting phosphor.
- Topilova,Meshkova,Dotsenko,Kovalevskaya,Kiriyak,Malinka,Efryushina
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p. 1932 - 1935
(2008/10/09)
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- Calorimetric study and thermal analysis of [Gd4/3Y2/3(Gly)6 (H2O)4](ClO4) 6·5H2O and [ErY(Gly)6(H2O)4] (ClO4)6·5
-
Two solid-state coordination compounds of rare earth metals with glycin, [Gd4/3Y2/3(Gly) 6(H2O)4](ClO4) 6·5H2O and [ErY(Gly)6(H2O)4] (
- Liu, Bei-Ping,Tan, Zhi-Cheng,Lan, Xiao-Zheng,Yu, Hua-Guang,Zhang, Da-Shun,Sun, Li-Xian
-
p. 233 - 238
(2008/10/08)
-
- Stepwise chlorination-chemical vapor transport reaction for rare earth oxide mixtures Gd2O3-Tb4O7, Tb4O7-Dy2O3 and Dy2O3-Ho2O3
-
Stepwise chlorination-chemical vapor transport (SC-CVT) reaction has been investigated for the rare earth oxide mixtures Gd2O3-Tb4O7, Tb4O7-Dy2O3 and Dy2O3-Ho2O3 mediated by vapor complexes LnAlnCl3n+3 (where Ln=rare earth elements). The results show selective deposition of lighter elements at higher temperatures. The separation factors are 5.84 for Gd/Tb, 3.72 for Tb/Dy and 3.13 for Ho/Dy when using CO as the CVT carrier gas. A combination of enhanced separation factor with reduced total transport yield is also observed for the Tb4O7-Dy2O3 system when using argon as the CVT carrier gas.
- Sun, Yan-Hui,Zhang, Li-Qing,Lei, Peng-Xiang,Wang, Zhi-Chang,Guo, Lei
-
p. 196 - 199
(2008/10/08)
-
- Synthesis and characterization of lanthanide(III) Schiff base complexes derived from cysteine and benzoin
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Six new complexes of the Schiff base ligand (HL) derived from benzoin and cysteine with Ln=La(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) of the type LnLCl2(H2O)2 have been synthesized and characterized by element
- Ma,Wang,Shi
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p. 617 - 627
(2008/10/08)
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- Synthesis, characterisation and thermal behaviour of solid stat compounds of 4-methylbenzylidenepyruvate with heavier trivalent lanthanides and yttrium(III)
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Solid state Ln-4-Me-BP compounds, where Ln stands for heavier trivalent lanthanides (gadolinium to lutetium) and yttrium(III) and 4-Me-BP is 4-methylbenzylidenepyruvate (CH3-C6H4-CH=CH-COCOO-), have been synthesized. Eleme
- Marques,Melios,Ionashiro
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p. 145 - 150
(2008/10/08)
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