46 research outputs found
A New Family of Porous Lanthanide-Containing Coordination Polymers : [ Ln2 (C2O4)3(H2O)6,12H2O] with Ln = La - Yb or Y
International audienceReactions at low temperature in a mixture benzene/water between dimethyloxalate and a lanthanide chloride lead to a family of 3D-coordination polymers with general chemical formula [Ln2(C2O4)3(H2O)6 3 12H2O]„, where Ln=La-Yb (except Pm) or Y. All these compounds are isostructural to the already described [Er2(C2O4)3(H2O)6 3 12H2O]„. Their crystal structure can be described as the juxtaposition of channels with hexagonal cross-section. The channels are filled with crystallization water molecules. Their thermal dehydration produces a collapse of the molecular skeleton leading to amorphous compounds.On the opposite, their dehydration by freeze-drying is possible and the twelve crystallization water molecules can be removed without destruction of the molecular skeleton. The porosity of the dehydrated compounds has been estimated by computational methods to 483 m2 g-1. The luminescence properties of the Eu-containing and Tb-containing compounds are also briefly described
Expanding the Toolbox of Octahedral Molybdenum Clusters and Nanocomposites Made Thereof: Evidence of Two-Photon Absorption Induced NIR Emission and Singlet Oxygen Production
International audienceBright NIR phosphorescence from octahedral molybdenum clusters has been known since the 1980s. However, their behavior toward NIR excitation has never been investigated. Here we report their abilities to emit NIR light and produce singlet oxygen upon two-photon absorption. This behavior is observed in solution, in the solid state, and when clusters are embedded homogeneously in a poly(dimethylsiloxane) matrix. Such discoveries open new perspectives in several fields like optoelectronics, photodynamic therapy, or bioimaging
Lanthanide Aminoisophthalate Coordination Polymers: A Promising System for Tunable Luminescent Properties
International audienceReactions in water between the disodium salt of 5-amino-1,3-benzenedicarboxylic acid or 5-aminoisophthalate (Na2aip) and lanthanide chlorides lead to two families of coordination polymers with the respective general chemical formulae {[Ln6(aip)7(H2O)24]*2(aip)*6H2O}â in which Ln = Tm or Yb (Family 1) and {[Ln2(aip)2(H2O)10]*(aip)*4H2O}â in which Ln = La-Er (except Pm) or Y (Family 2). Compounds belonging to Family 1 are isostructural. The crystal structure has been solved for the Er-containing compound. This compound crystallizes in the monoclinic system, space group P21/n (n°14) with a = 13.3439(3) Ă
, b = 27.3332(8) Ă
, c = 15.7191(4) Ă
, ÎČ = 97.90(1)°, V = 5680.41(82) Ă
3 and Z = 4. The crystal structure can be described as the juxtaposition of double helicoidal chains. Additional aminoisophthalate ions insuring the electroneutrality of the network are lying in the interchain space. Compounds belonging to Family 2 are isostructural. The crystal structure has been solved for the Eu-containing compound. This compound crystallizes in the monoclinic system, space group Pn (n°7) with a = 11.3427(2) Ă
, b = 10.6663(1) Ă
, c = 15.1639(3) Ă
, ÎČ = 97.8998(9)°, V = 1817.19(5) Ă
3 and Z = 2. The crystal structure can be described as the juxtaposition of zigzag double chains. Additional aminoisophthalate ligands are lying in the interchain space insuring the electroneutrality of the network. The luminescent properties under UV irradiation of these compounds have been explored. In particular, quantum yields, lifetimes and colorimetric coordinates of the Tb-, the Sm-, and the Dy-containing coordination polymers have been determined
One-Dimensional-Time Study of the Dehydration of Plasterboards Under Standard Fire Condition (ISO 834): Thermo-Chemical Analysis
International audienceGypsum materials are often used as a technical solution for passive fire protection in many civil engineering applications. In this study, the dehydration of plasterboard with large thickness, 40 mm, is studied using a one-dimensional (along the thickness) and time methodology analysis. Such materials are subjected on one side to a standard fire curve (ISO 834). The imposed heat transfer directly to the exposed face of the board induces combined actions due to the gypsum dehydration. The thermal barrier efficiency evolves significantly versus time. The local measurement of the temperature field through the sample and the local water content combined with the analysis of the local chemical structure helped us to model and analyze the dehydration processes
A Family of Lanthanide-Containing Molecular Open Frameworks with High Porosity: [Ln(abdc)(Habdc),nH2O]â with Ln = La - Eu and 8 †n †11
International audienceReactions in water between the di-sodium salt of amino terepthalic acid (C8H3NO4Na2) and a lanthanide chloride lead to a family of 3D-coordination polymers with general chemical formula [Ln(C8H3NO4)(C8H4NO4),nH2O]â where Ln = La-Eu (except Pm) and 8 †n †11. All these compounds are isostructural. High quality single crystals of [Ln(C8H3NO4)(C8H4NO4),nH2O]â with Ln = La-Sm (except Pm) and 8 †n †11 have been obtained by slow diffusion in agar-agar gels. The crystal structure has been solved for the Nd-containing compound. This compound crystallizes in the cubic system, space group Ia-3 (n°206) with a = 26.8056(5) Ă
. The crystal structure can be described as the juxtaposition of large channels with square cross-section. The channels are filled by highly disordered crystallization water molecules. The dehydration of the compounds by freeze-drying is possible and most of the crystallization water molecules can be removed without destruction of the molecular skeleton. The partially dehydrated compounds have general chemical formula [Ln(abdc)(Habdc),2H2O]â with Ln = La-Eu except Pm. The porosity of the Nd-containing compound has been estimated by computational methods to 2170 m2g-1. This dehydrated compound reversibly binds water when exposed to wet atmosphere restoring the initial hydrated phase
Brightness and Color Tuning in a Series of Lanthanide-Based Coordination Polymers with Benzene-1,2,4,5-tetracarboxylic Acid as a Ligand
International audienceReactions in water between the sodium salt of benzene-1,2,4,5-tetracarboxylic acid (H4btec) and lanthanide ions (Sm-Dy) led to a series of isostructural lanthanide-based coordination polymers with the general chemical formula [Ln4(btec)3(H2O)12·20H2O]â with Ln = Sm-Dy. The family has been structurally characterized. From a luminescent point of view, the heterodinuclear strategy has been successfully applied and allows significant brightness enhancement (+35%) and color tuning from green to yellow to orange to re
Erratum: Single-molecule magnet behaviour in polynuclear assembly of trivalent cerium ions with polyoxomolybdates (Dalton Transactions (2015) 44 (16458-16464))
International audienceCorrection for 'Single-molecule magnet behaviour in polynuclear assembly of trivalent cerium ions with polyoxomolybdates' by A. Ben Khélifa, et al., Dalton Trans., 2015, 44, 16458-16464
Extending the lanthanideâterephthalate system: Isolation of an unprecedented Tb(III)-based coordination polymer with high potential porosity and luminescence properties
International audienceA novel coordination polymer with chemical formula {[Tb(bdc)1.5(H2O)](DMF)(H2O)}1 (1) has been synthesizedby reaction between 1,4-benzene-dicarboxylic acid (H2bdc) and di-cationic hexanuclear entity[Tb6O(OH)8(NO3)6(H2O)12]2+ in an ethylene glycol (EG)/N,N-dimethylformamide (DMF) mixture. Thiscompound has been obtained as single crystals by slow evaporation in air at room temperature. If thehexanuclear entity is destroyed during the reaction, the coordination polymer that is obtained is originaland presents promising potential micro-porosity and luminescent properties. It crystallizes in the monoclinicsystem, space group C12/c1 (No. 15) with the cell parameters a = 23.7540(1) Ă
, b = 10.5390(4) Ă
,c = 19.7580(3) Ă
, b = 125.8100(1) and Z = 8
Closing the Circle of the Lanthanide-Murexide Series: Single-Molecule Magnet Behavior and Near-Infrared Emission of the NdIII Derivative
Up to now, even if murexide-based complexometric studies are performed with all 3d or 4f ions, the crystal structures of the light-lanthanide derivatives of the lanthanide-murexide series are unknown. In this work, we report the crystal structure of the NdIII derivative named NdMurex. Contrary to all known complexes of the 3d or 4f series, a dimeric compound was obtained. As for its already reported DyIII and YbIII parents, the NdIII complex responsible for the color-change behaves as a single-molecule magnet (SMM). This behavior was observed on both the crystalline (NdMurex: Ueff = 6.20(0.80) K, 4.31 cm−1; τ0 = 2.20(0.92) × 10−5 s, Hdc = 1200 Oe) and anhydrous form (NdMurexAnhy: Ueff = 6.25(0.90) K, 4.34 cm−1; τ0 = 4.85(0.40) × 10−5 s, Hdc = 1200 Oe). The SMM behavior is reported also for the anhydrous CeIII derivative (CeMurexAnhy: Ueff = 5.40(0.75) K, 3.75 cm−1; τ0 = 3.02(1.10) × 10−5 s, Hdc = 400 Oe). The Near-Infrared Emission NIR emission was observed for NdMurexAnhy and highlights its bifunctionality