Search results for "lanthanide"
showing 10 items of 230 documents
Solvent-modulated structures in anilato-based 2D coordination polymers
2017
Abstract This work highlights the key role of the solvents in the structures of the series of 2D compounds [Ln2(C6O4Br2)3·(Solvent)n]·G (G = Guest). This study is based on the affinity and ability of these solvents to coordinate to lanthanides and on their possibility to act as solvation molecules. For this purpose here we focus on the Er(III) ion and on the bromanilato bridging ligand ([C6O4Br2]2− = dianion of 3,6-dibromo-2,5-dihydroxy-1,4-benzoquinone) and we play with three solvents: H2O, DMSO (dimethylsulfoxide) and DMF (dimethylformamide). Here we report the synthesis, crystal structure and magnetic characterization of compounds [Er2(C6O4Br2)3(H2O)6]·12H2O (1), [Er2(C6O4Br2)3(DMSO)4]·2…
Mononuclear and polynuclear complexes ligated by an iminodiacetic acid derivative: synthesis, structure, solution studies and magnetic properties
2016
Two novel families of coordination polymers, [Ln(bzlida)(Hbzlida)]·H2O (Ln = La, Nd) and [Ln2(bzlida)3]·3H2O (Ln = Nd, Sm, Eu, Gd) were prepared by hydrothermal reaction of Ln2O3 with benzyliminodiacetic acid (H2bzlida). The conditions of synthesis, in particular the pH value, were selected on the basis of previous speciation studies reported in this work. The first type of complex consists of 1D chains built by a fully deprotonated ligand bridging two lanthanide ions and protonated Hbzlida(-) ligands connecting three cations. The second type is formed by [Ln2(bzlida)3] bimetallic units in which the ligand has a tridentate NOO coordination mode. This is expanded to a 2D network through carb…
Macrocyclic Pyclen-Based Gd3+ Complex with High Relaxivity and pH Response
2020
We report the synthesis and characterization of the macrocyclic ligand 2,2'-((2-(3,9-bis(carboxymethyl)-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane-6-yl)ethyl)azanediyl)diacetic acid (H4L) and several of its complexes with lanthanide ions. The structure of the free ligand was determined using X-ray diffraction measurements. Two N atoms of the pyclen moiety in the trans position are protonated in the solid state, together with the exocyclic N atom and one of the carboxylate groups of the ligand. The relaxivity of the Gd3+ complex was found to increase from 6.7 mM-1 s-1 at pH 8.6 to 8.5 mM-1 s-1 below pH ≈ 6.0. Luminescence lifetime measurements recorded from H2O and D2O solutions of the Eu3+ …
Asymmetric Ring Opening in a Tetrazine-Based Ligand Affords a Tetranuclear Opto-Magnetic Ytterbium Complex.
2020
We report the formation of a tetranuclear lanthanide cluster, [Yb4 (bpzch)2 (fod)10 ] (1), which occurs from a serendipitous ring opening of the functionalised tetrazine bridging ligand, bpztz (3,6-dipyrazin-2-yl-1,2,4,5-tetrazine) upon reacting with Yb(fod)3 (fod- =6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octandionate). Compound 1 was structurally elucidated via single-crystal X-ray crystallography and subsequently magnetically and spectroscopically characterised to analyse its magnetisation dynamics and its luminescence behaviour. Computational studies validate the observed MJ energy levels attained by spectroscopy and provides a clearer picture of the slow relaxation of the magnetisati…
Metal–Organic Frameworks as Playgrounds for Reticulate Single-Molecule Magnets
2019
Achieving an accurate control on the final structure of Metal-Organic Frameworks (MOFs) is mandatory to obtain target physical properties. Here we describe how the combination of a metalloligand design strategy and a post-synthetic method is a versatile and powerful approach to success on this extremely difficult task. In a first stage, a novel oxamato-based tetranuclear cobalt(III) complex with a tetrahedron-shape geometry is used, for the first time, as metalloligand toward cal-cium(II) cations to lead a diamagnetic Ca(II)-Co(III) three-dimensional (3D) MOF (1). In a second stage, in a single-crystal to single-crystal manner the calcium(II) ions are replaced by terbium (III), dysprosium(I…
Europium(III), Terbium(III), and Gadolinium(III) Oxamato-Based Coordination Polymers: Visible Luminescence and Slow Magnetic Relaxation
2021
The reaction of aqueous solutions of EuIII, TbIII, and GdIII ions with Na2Hpcpa [H3pcpa = N-(4-carboxyphenyl)oxamic acid] afforded three new isostructural oxamate-containing lanthanide(III) coordination polymers of general formula {LnIII2(Hpcpa)3(H2O)5·H2O}n [Ln = Eu (1),Tb (2), and Gd(3)]. Their structure is made up of neutral zigzag chains running parallel to the [101] direction where double syn-syn carboxylate(oxamate)-bridged dilanthanide(III) pairs (Ln1 and Ln2) are linked by three Hpcpa2- ligands, one of them with the μ-κ2O,O':κO″ coordination mode and the other two with the μ3-κ2O,O':κO″:κO'''. Additionally, two of those chains are interlinked through hydrogen bonding and π-π type in…
Yttrium and lanthanides in human lung fluids, probing the exposure to atmospheric fallout.
2011
International audience; Inhalation of airborne particles can produce crystallization of phosphatic microcrysts in intraaveolar areas of lungs, sometimes degenerating into pulmonary fibrosis. Results of this study indicate that these pathologies are induced by interactions between lung fluids and inhaled atmospheric dust in people exposed to volcanic dust ejected from Mount Etna in 2001. Here, the lung solid-liquid interaction is evaluated by the distribution of yttrium and lanthanides (YLn) in fluid bronchoalveolar lavages on selected individuals according the classical geochemical approaches. We found that shale-normalised patterns of yttrium and lanthanides have a 'V shaped' feature corre…
Catalytic activity of rare-earth-supported catalysts in Friedel–Crafts acylations
1999
Abstract Friedel–Crafts acylations are catalysed by rare-earth-supported catalysts. The preparation, characterization and performance of these solid catalysts in a test acylation reaction and in a variety of syntheses of aromatic ketones are reported. In contrast to the reactions using AlCl3, the experimental conditions are non-polluting and the final work-up does not require any aqueous treatment.
A fast method for apatite selective leaching from granitic rocks followed through rare earth elements and phosphorus determination by inductively cou…
2005
Abstract Rare earth elements (REE) and phosphorus (P) in apatite were determined using inductively coupled plasma optical emission spectrometry (ICP-OES) after partial dissolution of the granitic rocks and pure apatite. The dissolution was performed with nitric acid in an open system and the matrix elements were separated by a cation exchange procedure. Samples of pure apatite from granitic rocks were dissolved with, 0.14 mol L −1 nitric acid. The results showed that the release of REE is due to apatite leaching because it could be assessed by comparing the chondrite-normalised pattern corresponding to the rocks and the pure apatite. Similar results were found for absolute REE abundance fro…
Photocatalytic Degradation of 4-Nitrophenol in Aqueous Suspension by Using Polycrystalline TiO2 Impregnated with Lanthanide Double-Decker Phthalocyan…
2007
The photocatalytic activity of polycrystalline TiO2 samples impregnated with rare-earth-metal diphthalocyanines was investigated. The 4-nitrophenol (4-NP) photocatalytic degradation in aqueous suspension was used as a probe reaction. Commercial anatase TiO2 was impregnated with home-prepared double-decker phthalocyanine complexes of the lanthanide metals, such as Ce, Pr, Nd, Sm, Ho, and Gd. In particular, the impregnation with Ho, Sm, and Nd complexes, acting as sensitizers, proved beneficial for the photoactivity of the studied systems. Significant improvements of the TiO2-based catalytic system appeared possible in terms of lower impregnation loading, enhanced photoreactivity under solar …