10138-52-0Relevant articles and documents
Rare earth ethenide-halides Ln2n+6(C2) n+4X2n+2: Preparation, crystal structure, intergrowth and twinning
Mattausch, Hansjuergen,Kienle, Lorenz,Duppel, Viola,Hoch, Constantin,Simon, Arndt
, p. 1527 - 1535 (2009)
Preparation, crystal structure, intergrowth and twinning of the compounds La10(C2)6Br6, Ce10(C 2)Br6 and Gd10(C2) 6(Cl6 are described.
Formation of coordination compounds in gadolinium-loaded liquid organic scintillators (GdLS): Use of mixed-ligand gadolinium complexes in GdLS preparation
Novikova,Barabanov,Bezrukov,Belous,Danilov,Ivanov,Ziganshin,Yanovich
, p. 1082 - 1089 (2009)
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
Seifert, H. J.,Thiel, G.
, p. 197 - 202 (1989)
Pyridine and phosphonate containing ligands for stable lanthanide complexation. An experimental and theoretical study to assess the solution structure
Mato-Iglesias, Marta,Balogh, Edina,Platas-Iglesias, Carlos,Toth, Eva,De Blas, Andres,Rodriguez Blas, Teresa
, p. 5404 - 5415 (2006)
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.
Analysis of the conformational behavior and stability of the SAP and TSAP isomers of lanthanide(III) NB-DOTA-type chelates
Tircso, Gyula,Webber, Benjamin C.,Kucera, Benjamin E.,Young, Victor G.,Woods, Mark
, p. 7966 - 7979 (2011)
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.
Synthesis and crystal structure of 1D polyoxometalate-based composite compound, [{Gd(NMP)6}(PMo12O40)]n (NMP = N-methyl-2-pyrrolidone)
Niua, Jing-Yang,Wei, Mei-Lin,Wang, Jing-Ping,Dang, Dong-Bin
, p. 171 - 178 (2003)
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.
Extraction methods in development of Gd-loaded liquid organic scintillators for antineutrino detection: 2. Scintillators based on solutions of gadolinium 2-methylvalerate
Danilov,Krylov,Tsivadze,Barabanov,Bezrukov,Novikova,Yanovich,Demina,Cattadori,Di Vacri
, p. 274 - 282 (2009)
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.
Self-assembled light lanthanide oxalate architecture with controlled morphology, characterization, growing mechanism and optical property
He, Hongmei,Zhang, Youjin,Zhu, Wei,Zheng, Ao
, p. 1546 - 1552 (2011/10/01)
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.
Lanthanide carbonates
Janicki, Rafal,Starynowicz, Przemyslaw,Mondry, Anna
, p. 3601 - 3616 (2011/10/11)
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