共查询到20条相似文献,搜索用时 31 毫秒
1.
The conditions of formation of Y, La and lanthanide (from Ce(III) to Lu) enanthates were worked out, their composition and their solubilities in water at 291 K were determined, and the conditions of their thermal decomposition were studied. They were prepared as crystalline solids with general formula Ln(C 7H 13O 2) 3· nH 2O, where n=2–10. On heating, they decompose in two or three steps. They first lose some water molecules and then decompose to the oxides directly (salts of Y and heavy lanthanides) or via the intermediate formation of Ln 2O 2CO 3 (salts of La, Pr, Nd, Sm and Eu). Only yttrium enanthate dihydrate loses 2 water molecules on heating to form an anhydrous complex, which decomposes directly to Y 2O 3. The temperatures of dehydration are similar for all complexes (323–343 K), while the temperatures of oxide formation vary irregularly from 823 K for CeO 2 to 1078 K for La 2O 3. 相似文献
2.
Four new solid ternary complexes of lanthanide with 2,6-pyridine dicarboxylic acid and α-picolinic acid [Ln(DPA)(L α)(H 2O)] · 2H 2O (Ln = La 3+, Ce 3+, Eu 3+, or Gd 3+; DPA = 2,6-pyridine dicarboxylic acid; HL α = α-picolinic acid) have been synthesized and characterized by elemental analysis, molar conductance, FT-IR, UV–Vis, and TG–DTA. The antibacterial activities indicate that all the complexes exhibit antibacterial ability against Escherichia coli and Staphylococcus aureus with broad antimicrobial spectra. The anticancer activity of the La complex against K562 tumor cell in vitro is measured using methyl thiazolyl tetrazolium (MTT) colorimetry and flow cytometry. The La complex can induce K562 tumor cell apoptosis, presenting the best apoptosis effect by acting on the S period after inducing K562 tumor cell for 72 h. 相似文献
3.
New compounds with formulae Y(2,4′-bpy)1.5Cl3·8H2O (I), Y(2,4′-bpy)0.5Br3·8H2O (II), La(2,4′-bpy)Cl3·5H2O (III) and La(2,4′-bpy)1.5Br3·5H2O (IV) were prepared and characterized by chemical and elemental analysis, IR spectroscopy and powder X-ray diffraction. The thermal properties of compounds in the solid state were studied using TG-DTA techniques under dry air atmosphere. The thermal behavior of investigated compounds was studied in the temperature range 298–1273 K. They are stable up to 323 K. The complexes decompose in several stages, accompanied by endo- and exothermic effects. In all cases, the first step of pyrolysis is partial or total dehydration. When the temperature rises, deamination takes place. The solid final products of decomposition are Y2O3 and La2O3, respectively. Additionally, for all complexes mass spectrometry was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis under dry air atmosphere. 相似文献
4.
以1,1′-二羟基-5,5′-联四唑(H_2BTO)为配体,镧系金属离子作为金属中心,采用溶剂热法制备了5种金属配合物:[La_2(BTO)_3(H_2O)_8]·2H_2O (1)、[Ce_2(BTO)_3(H_2O)_8]·2H_2O (2)、[Pr_2(BTO)_3(H_2O)_8]·2H_2O (3)、[Sm_2(BTO)_3(H_2O)_8]·2H_2O (4)和[Nd_2(BTO)_3(DMF)_4]·6H_2O (5)。通过单晶X射线衍射和元素分析对5种配合物的结构进行了表征。结果表明,5种配合物均属于单斜晶系,P2_1/n空间群。利用差示扫描量热法研究了配合物1~4的热稳定性,采用Kissinger法和Ozawa法分别计算了其热分解动力学参数。 相似文献
5.
γ-Zirconium phosphate-phosphite, γ-Zr·PO 4·H 2PO 3·2H 2O, (γ-ZrPP), was prepared and characterized. Direct treatment of γ-zirconium phosphate-phosphite with an ethanol solution
of 0.1M 1,10-phenanthrolin and 2,2'-bipyridyl gave the well defined composites, γ-Zr·PO 4·H 2PO 3(phen) 0.15·H 2O and γ-Zr·PO 4·H 2PO 3(bipy) 0.18·0.6H 2O respectively. K
d
values of a mixture of lanthanide ions: La 3+, Sm 3+, Eu 3+ and Yb 3+ for the intercalated products and for γ-ZrPP in HNO 3 solution at room temperature and at pH 2 and 4 were determined by a radiotracer technique. 140La, 152mEu, 153Sm and 175Yb radioisotopes were used for the equilibration experiment using 500 μl (4.0·10 −5 mmole) each of the solutions of the tracers as a mixture in 7.5 M HNO 3 solution at the desired pH with 0.1 g of γ-ZrPP and of the intercalated products. The selectivity order was found to be dependent
on the nature of the ligand and on the pH. The 2,2'-bipyridyl product posseses, at pH 2 in general, a high K
d
value, specially for Sm 3+ (9815.9) compared to that of the 1,10-phenanthrolin product (3375.5) and to γ-ZrPP (419.8). This could be attributed to partial
deintercalation of the 2,2'-bipyridyl at pH 2 and increasing of ionogenic groups. 相似文献
6.
Thermal decomposition of Ln 2(C 2O 4) 3 · 9H 2O concentrate (Ln = La, Ce, Pr, Nd) in the presence of CaC 2O 4 · H 2O was studied by X-ray diffraction, thermogravimetry, and chemical analysis. Annealing at temperatures above 374°C in the absence of calcium oxalate gives rise to the solid solution of CeO 2-based rare-earth oxides. Calcite CaCO 3 is formed in the presence of calcium oxalate at annealing temperatures above 442°C, which impedes the formation of lanthanide oxide solid solution and favors crystallization of oxides as individual La 2O 3, CeO 2, Pr 6O 11, and Nd 2O 3 phases. An increase in temperature above 736°C is accompanied by decomposition of calcium carbonate to give rise to an individual CaO phase and an individual phase of CeO 2-based lanthanide oxide solid solution. 相似文献
7.
By diffusion in gel medium new complexes of formulae: Nd(btc)⋅6H 2O, Gd(btc)⋅4.5H 2O and Er(btc)·5H2O (where btc=(C 6H 3(COO) 3
3−) were obtained. Isomorphous compounds were crystallized in the form of globules. During heating in air atmosphere they lose
stepwise water molecules and then anhydrous complexes decompose to oxides.
Hydrothermally synthesized polycrystalline lanthanide trimellitates form two groups of isomorphous compounds. The light lanthanides
form very stable compounds of the formula Ln(btc)⋅ nH 2O (where Ln=Ce−Gd and n=0 for Ce; n=1 for Gd; n=1.5 for La, Pr, Nd; n=2 for Eu, Sm). They dehydrate above 250°C and then immediately decomposition process occurs. Heavy lanthanides form complexes
of formula Ln(btc)⋅ nH 2O ( Ln=Dy−Lu). For mostly complexes, dehydration occurs in one step forming stable in wide range temperature compounds. As the final
products of thermal decomposition lanthanide oxides are formed. 相似文献
8.
Four lanthanide complexes, [La 2(2,4-DClBA) 6(5,5′-DM-2,2′-bipy) 2(H 2O) 2]·2C 2H 5OH ( 1) and [Ln(2,4-DClBA) 3(5,5′-DM-2,2′-bipy)(C 2H 5OH)] 2 (Ln = Pr( 2), Sm( 3), Gd( 4); 2,4-DClBA = 2,4-dichlorobenzoate; 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridine), were synthesized and characterized via elemental analysis, infrared spectra and thermogravimetric analysis (TG). The crystal structures of 1 and 2–4 are different; Each La 3+ is nine-coordinate adopting a distorted mono-capped square antiprism, while the Ln 3+ ions of 2–4 are all eight-coordinate with a distorted square antiprismatic molecular geometry. There are subtle changes in the local coordination geometry of the lanthanide–5,5′-DM-2,2′-bipy complexes. Binuclear 1 complexes are stitched together via two kinds of hydrogen bonding interactions (OH?O and CH?O) to form 1-D chains along the y axis, while the units of 2–4 are stitched together via CH?O to form 1-D chains along the x axis. TG analysis revealed thermal decomposition processes and thermal stabilities of the complexes. The bacteriostatic activities of the complexes were evaluated against Candida albicans, Escherichia coli, and Staphylococcus aureus. 相似文献
9.
Two discrete lanthanide complexes with bulky aromatic mixed‐ligands, {[La 2(na) 6(phen) 2]·[La 2(na) 6(phen) 2]} ( 1 ) and [La 2(na) 6(2,2′‐bipy) 2] ( 2 ) (Hna = 1‐naphthoic acid, phen = 1,10‐phenanthroline, and 2,2′‐bipy = 2,2′‐bipyridine), have been synthesized under hydrothermal conditions and fully characterized by single‐crystal X‐ray crystallography, IR, elemental analysis, TG‐DTA and fluorescence spectra. Structure determination reveals that 1 contains two separate binuclear [La 2(na) 6(phen) 2] units, in which both crystallographically La III ions are nine‐coordinated with tricapped trigonal prism polyhedron for La1 and a distorted monocapped square antiprism arrangement for La2; whereas 2 has a binuclear structure bridged by carboxylate groups of four na anions. Due to the introduction of bulky aromatic ligands, non‐classical C–H···O H–bonds and π – involved stacking interactions become the dominantly driving forces for the supramolecular structure. The two solid complexes exhibit intense fluorescent emissions at room temperature resulted from the ligand‐to‐metal charge transfer. 相似文献
10.
Lanthanide complexes Ln( p-ABA) 3·H 2O ( p-ABA: p-aminobenzoic acid; Ln 3+:La 3+, Tb 3+ and Er 3+) have been incorporated into silica gels via a sol–gel method. Upon heat treatment at 120 °C, photoacoustic (PA) intensity of the ligand increases for Tb 3+, La 3+ and Er 3+ complexes in silica gels, respectively, while this difference cannot be observed for the samples without heat treatment. Different PA intensities of the samples are interpreted by comparison with their luminescence spectra. The nephelauxetic parameters and PA branching vectors of Er 3+ complex in silica gel have been calculated. Spectral results indicate that p-ABA does not coordinate with lanthanide ions in silica matrix without a suitable heat treatment. For the co-doped samples, it is shown that the emissions of Tb 3+ are enhanced with addition of La( p-ABA) 3·H 2O and remarkably quenched with the addition of Er( p-ABA) 3·H 2O. The possible mechanisms for these phenomena are proposed. 相似文献
11.
Two isostructural dinuclear lanthanide(III)/Schiff-base complexes [{Ce 1.5Eu 0.5(clapi)} 2]·2CH 3CN ( 1) and [{La 1.5Eu 0.5(clapi)} 2]·2CH 3CN ( 2) {H 3clapi = 2-(5-chloride-2-hydroxyphenyl)-1,3-bis[4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared by template procedure and characterized by elemental analyses, ICP, IR, and single-crystal X-ray diffraction analyses. Lanthanide ions Ce(III) and Eu(III) in 1, and La(III) and Eu(III) in 2 are disordered with occupancies 0.75 for Ce and 0.25 for Eu in 1; 0.75 for La and 0.25 for Eu in 2. In the compounds, each lanthanide is coordinated to four N and four O atoms from two clapi 3? ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate μ 2-bridging ligands connect the two Ce(Eu) atoms in 1, and La(Eu) in 2. The solution of the two complexes in CH 2Cl 2 exhibits red fluorescence from Eu 3+ ions at 77 K, very weak at room temperature. 相似文献
12.
One new 3D La‐Ag coordination compound formulated as [La 2Ag 3(IN) 6(OAC)(H 2O) 3][NO 3] 2 · 2H 2O ( 1 ) (HIN = isonicotinic acid; HOAC = acetic acid) was synthesized. The structure represents an interesting 3D open framework that is built upon 2D lanthanide layers and [Ag(IN) 2] + linkers. The triple helical [La(IN) 2(H 2O)] n chain and zigzag [LaIN(OAC)] n chain are found in the 2D La‐IN layers. Channels are also found in the framework of 1 , owing to shape‐controlled synthesis templated by the free NO 3– ions and water molecules. 相似文献
13.
Lighter and heavier lanthanide(III) ions react with dihydrazinium salts of ethylenediaminetetraacetic acid (H4edta) in aqueous
solution to yield hydrazinium lanthanide ethylenediaminetetraacetate hydrate, N 2H 5[Ln(edta)(H 2O) 3]·(H 2O) 5 where Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Dy. The numbers of water molecules present inside the coordination sphere have been confirmed
by X-ray single crystal studies. The presence of five water molecules as lattice water is clearly shown by the mass loss from
the TG analyses. Dehydration of a known amount (1 g) of each sample were carried out at constant temperature (100–110°C) for
about 5 min further confirms the number of non-coordinated water molecules. The complexes after the removal of lattice water
undergo multi-step decomposition to give respective metal oxide as the final product. The DTA shows endotherms for dehydration
and exotherms for the decomposition of the anhydrous complexes. The formation of the metal oxides was confirmed by X-ray powder
diffraction studies. 相似文献
14.
An exchange reaction of the sodium salt of 3-methyl-1-phenyl-4-formylpyrazol-5-one (HL) with chlorides or nitrates of lanthanides
(Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, and Yb) was used to synthesize coordination compounds of composition LnL 3· nSolv (Solv = H 2O or EtOH). According to powder X-ray diffraction data, these compounds constitute two series: one comprises lanthanum and
neodymium complexes, and the other, samarium, europium, gadolinium, terbium, dysprosium, and ytterbium complexes. For the
complexes of the first series, the structure was solved in a single-crystal diffraction experiment carried out on [La 2(μ-L) 3(L) 3(H 2O) 3]·2MeOH. The lanthanum atoms in the complex are at a distance of 4.222(2) — from each other, and they are structurally nonequivalent
and linked by three 5-hydroxy-4-formylpyrazole anions. Solid-phase samples of the coordination compounds under study feature
weak luminescence in the spectral regions intrinsic to lanthanide cations. 相似文献
15.
The Lanthanum Dodecahydro‐ closo‐Dodecaborate Hydrate [La(H 2O) 9] 2[B 12H 12] 3·15 H 2O and its Oxonium‐Chloride Derivative [La(H 2O) 9](H 3O)Cl 2[B 12H 12]·H 2O By neutralization of an aqueous solution of the free acid (H 3O) 2[B 12H 12] with basic La 2O 3 and after isothermic evaporation colourless, face‐rich single crystals of a water‐rich lanthanum(III) dodecahydro‐ closo‐dodecaborate hydrate [La(H 2O) 9] 2[B 12H 12] 3·15 H 2O are isolated. The compound crystallizes in the trigonal system with the centrosymmetric space group ( a = 1189.95(2), c = 7313.27(9) pm, c/a = 6.146; Z = 6; measuring temperature: 100 K). The crystal structure of [La(H 2O) 9] 2[B 12H 12] 3·15 H 2O can be characterized by two of each other independent, one into another posed motives of lattice components. The [B 12H 12] 2− anions (d(B–B) = 177–179 pm; d(B–H) = 105–116 pm) are arranged according to the samarium structure, while the La 3+ cations are arranged according to the copper structure. The lanthanum cations are coordinated in first sphere by nine oxygen atoms from water molecules in form of a threecapped trigonal prism (d(La–O) = 251–262 pm). A coordinative influence of the [B 12H 12] 2− anions on La 3+ has not been determined. Since “zeolitic” water of hydratation is also present, obviously the classical H–O δ–··· +δH–O‐hydrogen bonds play a significant role in the stabilization of the crystal structure. During the conversion of an aqueous solution of (H 3O) 2[B 12H 12] with lanthanum trichloride an anion‐mixed salt with the composition [La(H 2O) 9](H 3O)Cl 2[B 12H 12]·H 2O is obtained. The compound crystallizes in the hexagonal system with the non‐centrosymmetric space group ( a = 808.84(3), c = 2064.51(8) pm, c/a = 2.552; Z = 2; measuring temperature: 293 K). The crystal structure can be characterized as a layer‐like structure, in which [B 12H 12] 2− anions and H 3O + cations alternate with layers of [La(H 2O) 9] 3+ cations (d(La–O) = 252–260 pm) and Cl − anions along [001]. The [B 12H 12] 2− (d(B–B) = 176–179 pm; d(B–H) = 104–113 pm) and Cl − anions exhibit no coordinative influence on La 3+. Hydrogen bonds are formed between the H 3O + cations and [B 12H 12] 2− anions, also between the water molecules of [La(H 2O) 9] 3+ and Cl − anions, which contribute to the stabilization of the crystal structure. 相似文献
16.
Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light
lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln 2L 3· nH 2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na 2L·H 2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas
Na 2L·H 2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate
lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm −1 disappear on complex spectra and ν as and ν s of COO − groups appear thus indicating that complexation process took place. 相似文献
17.
The thermal decomposition of several lanthanide salts Ln(CF 3COO) 3·3H 2O ( Ln=La, Gd, Tb) was studied under quasi-equilibrium conditions and under linear heating. According to mass spectral data, H 2O is the single product of thermal decomposition up to 120-140°C. Thermogravimetric data were processed with 'Netzsch Thermokinetics'
computer program. Kinetics parameters of the first decomposition step (as the simple dehydration process, not complicated
by the water hydrolysis with the liberation or the decomposition of the organic ligand) were calculated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
In the title complex, {[La 2(C 5H 6O 4) 3(H 2O) 4]·H 2O} n, the La atoms are connected by bridging O atoms from carboxylate groups to build, through centres of inversion, two‐dimensional layers parallel to the ac plane containing decanuclear 20‐membered rings. The coordinated water molecules are involved in intralayer hydrogen‐bond interactions. Adjacent layers are linked via hydrogen bonding to the solvent water molecules. This work represents the first example of a new substituted malonate–lanthanide complex. 相似文献
19.
Solid complexes of five derivatives of thio-Schiff bases with La(III) and Ce(III) ions were prepared and characterized by elemental and thermogravimetric analyses. The suggested general formula of the solid complexes is [ML 2(H 2O)X]·2H 2O, where M=trivalent lanthanide ion, L=Schiff base and X=Cl ? or ClO 4 ? . Information about the water of hydration, the coordinated water molecules, the coordination chemistry and the thermal stability of these complexes was obtained and is discussed. Additionally, a general scheme of thermal decomposition of the lanthanide-Schiff base complexes is proposed. 相似文献
20.
Three new lanthanide(III) complexes with N-(2-propionic acid)-salicyloylhydrazone (H 2L, C 10H 10N 2O 4) ligand [La(HL) 2(NO 3)(H 2O) 2] 3 ·4H 2O( I), [Gd(HL) 3] · 2(C 2H 5) 3 N( II) and [Er(L)(HL)(H 2O) 2] · 2H 2O( III) has been synthesized and characterized by elemental analyses, IR, UV, and molar conductivity. The crystal structures of
three complexes have been determined by X-ray single-crystal diffractometer. In complex I, the La 3+ ion is ten-coordinated by two tridentate ligands, one bidentate nitrate, and two water molecules. In complex II, the Gd 3+ ion has a coordination number of nine by three tridentate ligands. In complex III, the Er 3+ ion is eight-coordinated by two tridentate ligands and two water molecules. In all structures, tridentate ligands are coordinated
by carboxyl O and acyl O atoms and azomethine N atom to form two stable five-membered rings sharing one side in the keto mode
as indicated by the results of crystal structures and infrared spectral analysis. 相似文献
|