Complexes Of Rare Earth Picrates Research Articles

Dinuclear rare-earth picrate complexes based on a multidentate amide ligand: syntheses, crystal structures, and luminescence properties

A new amide-based multidentate ligand, N,N′-1,2-ethanediyl-bis{2-[(N,N-diethylcarbamoyl)methoxy]benzamide} (L) reacts with M(Pic)3 · 6H2O to give rare-earth picrate complexes [M2L2(Pic)4(H2O)2](Pic)2 (M = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Yb (7), Y (8)). X-ray single-crystal diffraction analyses indicate that dinuclear complexes 3 · 2C4H8O2, 6 · 2C4H8O2, and 8 · 2CH3CN are isomorphous. Each metal is nine-coordinate by four oxygen atoms of two ligands, four oxygen atoms of two bidentate picrates, and one water molecule with a distorted monocapped square antiprism. With hydrogen bonds between the free picrate anions and the coordination cations the complexes exhibit 2-D layers. The luminescent properties of 3 [Eu2L2(Pic)4(H2O)2](Pic)2 are described and factors that influence luminescent intensities are also discussed.

Synthesis, characterization and luminescence properties of rare earth complexes with a new biphenylamide

A new amide-based ligand derived from biphenyl, N,N-dibenzyl-2-{2′-[(dibenzylcarbamoyl)-methoxy]-biphenyl-2-yloxy}-acetamide (L), and its complexes of rare earth picrates were synthesized. The complexes were characterized by elemental analysis, IR, 1H NMR, UV–Vis spectra and conductivity measurements. Under the excitation, the europium(III) complex exhibited characteristic emissions of europium. The luminescence properties of the europium(III) complex in solid state and in CHCl3, acetone, acetonitrile and DMF were investigated. The lifetime of the 5D0 level of the Eu3+ ion in the complex is 0.68ms. The quantum yield Φ of the europium picrate complex was found to be 2.54×10−3 with quinine sulfate as reference. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion.

Synthesis, crystal structure, and luminescence properties of rare-earth complexes with 2,2′-bis[(diethylcarbamoyl)- methoxy]-1,1′-biphenylene

A new amide-based ligand derived from biphenyl, 2,2′-bis[(diethylcarbamoyl)-methoxy]-1,1′-biphenylene (L), and its complexes of rare-earth picrates were synthesized. Solid complexes of lanthanide picrates (Ln = La, Nd, Eu, Gd, Tb, and Y) with this new ligand were prepared and characterized by elemental analysis, conductivity measurements, X-ray powder diffraction, and infrared spectroscopies. The molecular structure of [Gd(pic)3L] shows that the Gd(III) is eight-coordinate by four oxygen atoms from L and the other from one bidentate and two unidentate picrates. Furthermore, [Gd(pic)3L] units are linked by intermolecular hydrogen bonds to generate a 2-D netlike supramolecule. Under excitation, the Eu(III) complex exhibited characteristic emissions of europium. The luminescence properties of the Eu(III) complex in solid state and in CHCl3, acetone, acetonitrile, and DMF were investigated. The lifetime of the 5 D 0 level of Eu(III) in the complex was 0.26 ms. The quantum yield Φ of the europium picrate complex was 6.67 × 10−3 with quinine sulfate as reference. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III).

Synthesis and spectroscopic properties of rare earth picrate complexes with a new dinaphthalenelamide

The new ligand N-benzyl-2-{2'-[(benzyl-ethyl-carbamoyl)-methoxy]-dinaphthalene-2-yloxy}-N-ethyl-acetamide (L) and its complexes of rare earth picrates were synthesized. The complexes were characterized by elemental analysis, IR, UV-vis spectra and conductivity measurements. The fluorescence properties of the europium complex in solid state and CHCl 3, ethyl acetone, acetonitrile and DMF were investigated. Under the excitation, the europium complex exhibited characteristic emissions of europium. The lowest triplet state energy level of the ligand indicated that the triplet state energy level of the ligand matched better to the resonance level of Eu(III) than Tb(III) ion.

Synthesis and spectroscopic properties of rare earth picrate complexes with a new biphenylamide

The new ligand N-benzyl-2-{2′-[(benzyl-ethyl-carbamoyl)-methoxy]-biphenyl-2-yloxy}- N-ethyl-acetamide (L) and its complexes of rare earth picrates were synthesized. The complexes were characterized by elemental analysis, IR, UV–vis spectra and conductivity measurements. The fluorescence properties of the europium complex in solid state and in CHCl 3, ethyl acetate, acetone, acetonitrile and DMF were investigated. Under the excitation, the europium complex exhibited characteristic emissions of europium. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion.

Synthesis, characterization, spectroscopy and thermal analysis of rare earth picrate complexes with L-leucine

Rare earth picrate complexes with L-leucine (Leu) were synthesized and characterized. Elemental analysis (CHN), EDTA titrations and thermogravimetric data suggest a general formula RE(pic)32Leu⋅5H2O (RE=La–Lu, Y and pic=picrate). IR spectra indicate the presence of water and suggest that L-leucine is coordinated to the central ion through the nitrogen of the aminogroup. The absorption spectrum of the solid Nd compound indicates that the metal-ligand bonds show a weak covalent character. Emission spectra and biexponential behavior of the luminescence decay of the Eu compound suggest the existence of polymeric species. Thermal analysis results indicate that all the compounds present a similar behavior, with five major thermal decomposition steps. The final products are rare earth oxides. A slow heating rate is necessary to observe all decomposition steps.

Synthesis, characterization, spectroscopy and thermal analysis of rare earth picrate complexes with L-lysine

Synthesis, characterization, spectroscopy and thermal analysis of rare earth picrate complexes with L-lysine

Synthesis, characterization, spectroscopic study and thermal analysis of rare-earth picrate complexes with l-arginine

Rare-earth picrate complexes with l-arginine were synthesized and characterized. Analysis of carbon, hydrogen, nitrogen and thermal analysis data suggest a general formula Ln(pic)3·2l-Arg·2H2O (Ln=La–Lu, Y, pic=picrate, l-Arg=arginine). IR spectra indicate the presence of water molecules and suggest that l-arginine is coordinated to the central ion through the nitrogen of the amine group. Bands due to picrate ions also indicate that at least in part they are coordinated as bidentate through the phenoxo group and one oxygen of an ortho-nitro group. X-ray diffraction powder pattern results indicate that these complexes are very similar in structure. The parameters obtained from the absorption spectrum of the solid Nd compound indicated that the metal–ligand bonds present weak covalent character. The emission spectra of the Eu compound indicate the existence of different europium coordinaton environments. Thermal analyses results indicated that all the compounds present a similar behavior.

Synthesis, Characterization and Crystal Structure of Complexes of Rare Earth Picrates with N,N,N',N',N",N"-Hexaisopropyl- 2,2',2"-[nitrilotris(ethyleneoxy)]triacetamide (L)

A new tripodal compound, N,N,N',N',N",N"-hexaisopropyl-2,2',2"-[nitrilotris(ethyleneoxy)]triacetamide (L) was synthesized. Its complexes with rare earth picrates, [M(Pic)L](Pic)2·H2O (M = La, Pr, Nd, Sm, Eu, Tb, Er, Yb, Y), have been prepared and characterized by elemental analysis, thermal analysis, conductivity measurements, IR and 1H NMR spectra. The crystal structures of two complexes [M(Pic)L](Pic)2 (M = Sm, Y) have been determined, which reveal that the M(III) ions (M = Sm, Y) are encapsulated by the three chains of the ligand and nine-coordinated by the central nitrogen atom, three ether oxygen atoms and three carbonyl oxygen atoms from the ligand, and two oxygen atoms from the didentate coordinated picrate ion in both cases. The results show that L acts as a heptadentate ligand, forming a cup-like coordination structure to accommodate the rare earth ion. Both rare earth complexes have the similar coordinate modes in spite of different unit cells.

Crystal structures of the complexes of rare earth picrates with N, N, N′, N′-tetraphenyl-3, 6-dioxaoctanediamide

The complexes of rare earth picrate with N, N, N′, N′-tetraphenyl-3, 6-dioxaoctanediamide (TDD), [Eu(pic)3(TDD)]-2CH3CN and [Y(pic)3(TDD)], have been synthesized. The crystal structures reveal that TDD acts as a tetradentate ligand, forming a ring-like coordination structure with its oxygen atoms together with one oxygen atom of the bidentate picrate. In the Eu (III) complex, the europium ion with a larger ionic radius lies out of the ring, while in the Y (III) complex, the yttrium ion with a smaller ionic radius enters the cavity of the ligand. The structures of the complexes are greatly affected by the ionic radii due to participation of the picrates in coordination.

Studies on the coordination behaviour of 1,3-phenylenebis(formyloxyacetyl-4′-benzo-15-crown-5)

Yellow solid complexes having the stoichiometric formula KLPic and Na 2L (Pic) 2 · 2H 2O (L = 1,3-phenylenebis(formyloxyacetyl-4′-benzo-15-crown-5), Pic = picrate anion) were obtained from chloroform-methanol mixtures. The results of the characterization of the two complexes by IR, NMR, UV-vis spectra and molar conductance indicated that a 2: 1 complex of crown-separated ion pair (benzo-15-crown-5 unit to K +) and a 1: 1 complex of contact ion pair (benzo-15-crown-5 unit to Na +) are formed, respectively. 13C NMR spectra showed that the carbonyl groups on the bridging chain do not take part in the coordination of the picrates. A PVC membrane K +-selective electrode based on the title ligand (L) was also studied. The 11 kinds of new, coloured, solid rare earth picrate complexes with the stoichiometric formula Ln(Pic) 3 · L · nH 2O (Ln  La, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Yb, Y, n = 5 or 6) were prepared in an ethanol-chloroform mixture. By elemental analysis, IR, UV-vis spectra, molar conductance and DTA-TG, these complexes were proposed as supermolecules in which the title ligand acts as second-sphere ligand, and Ln(Pic) 3 is associated with the ligand by intermolecular forces.