15 research outputs found
A new series of lanthanide-based complexes with a bis(hydroxy)benzoxaborolone ligand Synthesis, crystal structure, and magnetic and optical properties
International audienceReactions, under hydrothermal conditions, between lanthanide chlorides and the sodium salt of 2-carboxyphenylboronic acid lead to a series of lanthanide-based complexes with general chemical formula [Ln2(C7H5O2)4(C7O4H6B)2·4H2O] with Ln = Eu–Dy. During the synthetic process, the 2-carboxyphenylboronate ligand decomposes leading to benzoate (C7H5O2) and bis(hydroxy)benzoxaborolone (C7O2H6B). The crystal structure was solved on the basis of the Tb-derivative. It crystalizes in the triclinic system, space group P[1 with combining macron] (n° 2) with a = 9.3329(13) Å, b = 16.012(2) Å, c = 16.212(2) Å, α = 107.789(5)°, β = 90.226(5)°, γ = 97.585(5)°, V = 2284.16(52) Å3 and Z = 2. Its crystal structure can be described on the basis of di-lanthanides entities surrounded by ligands. Compounds that constitute this series are thermally stable up to 190 °C. Solid-state luminescence properties have been studied in detail. The magnetic properties of the Dy-derivative have also been explored. It exhibits single molecule magnet behavior. Single crystals of the sodium salt of 2-carboxyphenylboronic acid with chemical formula [Na(C7O4H6B)(H2O)]∞ have also been obtained during this study. This compound crystallizes in the orthorhombic system, space group P212121 (n° 19) with a = 4.5881(13) Å, b = 6.5905(16) Å, c = 29.644(8) Å, V = 897.0(4) Å3 and Z = 4. Its crystal structure is 2D and can be described as zigzag chains of sodium 2-carboxyphenylboronate bound to each other by coordination water molecules
Luminescence properties of lanthanide complexes-based molecular alloys
International audienceSix lanthanides complexes with chemical formula [Ln(phen)2(NO3)3] (Ln = Sm(1), Tb (2), Nd (3), Eu (4), Ho (5) and Y (6), phen = 1,10-phenanthroline) were synthesized. 1 and 2 were obtained as single crystals by slow diffusion. Structural characterization was based on single crystal X-ray diffraction and IR and 89Y-NMR spectroscopies. NMR spectroscopic measurements were performed on [Y(phen)2(NO3)3] (6) and [Y0.75Lu0.25(phen)2(NO3)3] (7). Compounds obtained as microcrystalline powders were characterized by powder X-ray diffraction. The complexes crystallize in the monoclinic system, space group P21/n. Each Ln(III) ion is surrounded by four N atoms from two bidentate phenanthroline ligands and six O atoms from three chelating nitrate groups. The phenanthroline ligand provides efficient sensitization of the complexes that exhibit sizeable luminescence under UV irradiation. Thermal properties have been studied. They confirm the absence of water molecules in the crystal structure. The complexes are thermally stable up to 290 °C. Microcrystalline powders of hetero-lanthanide complexes, with global chemical formula [Tb1−xEux(phen)2(NO3)3] (series 8) and [Tb1−xGdx(phen)2(NO3)3] (series 9) were synthesized. Their photo-physical properties have been investigated. They demonstrate that luminescent molecular alloys can be obtained from lanthanides complexes and not only from hetero-nuclear coordination polymers as previously reported
Tunable trimers: Using temperature and pressure to control luminescent emission in gold(i) pyrazolate-based trimers
A systematic investigation into the relationship between the solid-state luminescence and the intermolecular AuAu interactions in a series of pyrazolate-based gold(I) trimers; tris(μ2-pyrazolato-N,N')-tri-gold(I) (1), tris(μ2-3,4,5- trimethylpyrazolato-N,N')-tri-gold(I) (2), tris(μ2-3-methyl-5- phenylpyrazolato-N,N')-tri-gold(I) (3) and tris(μ2-3,5-diphenylpyrazolato- N,N')-tri-gold(I) (4) has been carried out using variable temperature and high pressure X-ray crystallography, solid-state emission spectroscopy, Raman spectroscopy and computational techniques. Single-crystal X-ray studies show that there is a significant reduction in the intertrimer AuAu distances both with decreasing temperature and increasing pressure. In the four complexes, the reduction in temperature from 293 to 100 K is accompanied by a reduction in the shortest intermolecular AuAu contacts of between 0.04 and 0.08 The solid-state luminescent emission spectra of 1 and 2 display a red shift with decreasing temperature or increasing pressure. Compound 3 does not emit under ambient conditions but displays increasingly red-shifted luminescence upon cooling or compression. Compound 4 remains emissionless, consistent with the absence of intermolecular AuAu interactions. The largest pressure induced shift in emission is observed in 2 with a red shift of approximately 630 cm-1 per GPa between ambient and 3.80 GPa. The shifts in all the complexes can be correlated with changes in AuAu distance observed by diffraction. © 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
High Luminance of Heterolanthanide-Based Molecular Alloys by Phase-Induction Strategy
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Structures, Thermal Behaviors, and Luminescent Properties of Anhydrous Lanthanum Iodate Polymorphs
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