Thermolysis of lanthanide dithiocarbamate complexes

Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex. The synthesis temperatures are generally lower than standard solid state preparations, avoid toxic sulfurizing gases and provide a convenient route to prepare lanthanide chalcogenide nanoparticles. Depending on the reaction conditions and oxophilicity of the lanthanide, the sulfide material was formed with oxidized products including oxysulfides, oxysulfates and the oxide.     

Enhancement of near-IR emission by bromine substitution in lanthanide complexes with 2-carboxamide-8-hydroxyquinoline

Three novel 2-carboxamide-8-hydroxyquinoline derivatives wrap helically around trivalent lanthanide ions to form monometallic 3 : 1 complexes possessing strong NIR emission.     

Thermal Behaviour of Oxovanadium(IV) Complexes of Halogenated Derivatives of 8-hydroxyquinoline

The thermal behaviour of a series of oxovanadium(IV) complexes of halogenated derivatives of 8-hydroxyquinoline was investigated by means of TG and DTA measurements in oxygen atmosphere. V₂O₅ was the final pyrolysis residue in all cases.This revised version was published online in November 2005 with corrections to the Cover Date.     

Some lanthanide metal complexes of n-isonicotinamidosalicylaldimine

Trivalent lanthanide complexes of the type K[ML ₂] whereM=La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III) and Dy(III) and H₂ L=N-isonicotinamidosalicyladimine, have been prepared and characterised. The nephelauxetic ratio (β), covalency (δ) and bonding parameter (b ²) of K[NdL ₂] have been calculated. Infrared spectral studies reveal that N-isonicotinamidosalicylaldimine acts as a dibasic tridentate ligand. A coordination number six has been proposed for the lanthanide metal ions.     

Chiral tripode approach toward multiple anion sensing with lanthanide complexes

A chiral tripodal ligand was demonstrated to form a series of lanthanide complexes exhibiting multiple anion-sensing profiles, which incorporated a fluorescent quinoline and a stereo-controlled substituent in a tetradentate skeleton. This mainly gave 1:2 (lanthanide cation/ligand) complexes with lanthanide triflates but 1:1 complexes with lanthanide nitrates. Since addition of external guest anion dynamically changed the preferred stoichiometry, the chiral lanthanide complexes exhibited anion-responsive fluorescence, luminescence, and circular dichroism spectral characteristics as multiple anion-sensing probes.     

Syntheses and characterization of novel lanthanide adamantine-dicarboxylate coordination complexes

Hydrothermal reactions of 1,10-phenanthroline (phen), 1,3-adamantanedicarboxylic acid (H₂L) and lanthanide chlorides yielded six compounds: [Ln(L)(HL)(phen)] (Ln=Pr, 1; Nd, 2), [Ln(L)(HL)(phen)(H₂O)] (Sm, 3; Eu, 4), [Tb(L)(HL)(phen)(H₂O)]₂·2H₂O (5), [Er₃(L)₄(OH)(phen)]₂ (6). Compounds 1-4 are structurally featured by one-dimensional polymeric chains; 5 hold binuclear structure constructed from eight-coordinated lanthanide center LnN₂O₆ of distorted bicapped trigonal prism bridged by dicarboxylate ligands; 6 shows that erbium ions are in mono and bicapped trigonal prismatic geometries, respectively, which are further connected by μ₃-OH to give rise to trinuclear structure. Thermogravimetric analyses of 1, 3 and 5 were performed. Fluorescent measurements of 4 and 5 were carried out, respectively.     

2,4-Lutidine-1-oxide complexes of lanthanide perchlorates

2,4-Lutidine-1-oxide (2,4-LutO) complexes of lanthanide perchlorates of the formulae Ln₂(2,4-LutO)₁₃(ClO₄)₆ (Ln = Pr and Nd) and Ln₂(2,4-LutO)₁₅ (ClO₄)₆ (Ln = La, Tb, Dy, Ho and Yb) have been prepared and characterised by chemical analysis, IR, NMR, conductance and electronic spectral data. Proton NMR data along with the IR data show that the ligand coordinates to the metal ion through the oxygen. Conductance data of the complexes in acetone and nitrobenzene indicate that the perchlorate is not coordinated to the metal ion.     

Sensitized luminescence in dinuclear lanthanide(III) complexes of bridging 8-hydroxyquinoline derivatives with different electronic properties

Three new dinuclear lanthanide(III) complexes {Eu(hfac)(3)(H(2)O)}(2)(μ-HPhMq)(2) (2) and {Ln(hfac)(3)(H(2)O)}(2)(μ-HMe(2)NC(6)H(4)Mq)(2) (Ln = Eu, 3; Nd, 4) with 8-hydroxylquinoline derivatives in μ-phenol mode were synthesized and characterized, where hfac(-) = hexafluoroacetylacetonate, HPhMq = 2-methyl-5-phenylquinolin-8-ol, and HMe(2)C(6)H(4)Mq = 5-(4-(dimethylamino)phenyl)-2-methylquinolin-8-ol. Compared with that (400 nm) for {Eu(hfac)(3)}(2)(μ-HMq)(2) (1, HMq = 2-methy-8-hydroxylquinoline), the excitation wavelength for sensitized lanthanide luminescence is extended to ca. 420 nm for 2, and 500 nm for 4 by introducing a phenyl or 4-(dimethylamino)phenyl to 8-hydroxylquinoline. These dinuclear lanthanide(III) complexes exhibit distinctly fluoride-induced lanthanide(III) emission enhancement in both intensity and lifetime due to replacing coordination water molecules or formation of strong O-H···F hydrogen bonds with coordinated H(2)O and μ-phenol, thus suppressing significantly the non-radiative O-H oscillators.     

Dual-emissive complexes: Visible and near-infrared luminescence from bis-pyrenyl lanthanide(III) complexes

The syntheses and photophysical attributes of a range of dual-emissive lanthanide complexes are described. The simple ligand architecture is based upon a diethylenetriaminepentaacetic acid (DTPA) core and appended with two aminopyrenyl chromophores to yield the fluorescent free ligand L^pyr. Reaction of the ligand with Ln(tris-trifluoromethanosulfate) gave the mononuclear complexes Ln · L^pyr (Ln = Nd, Er, Yb). Luminescence studies revealed that the complexes were emissive in both the near-IR and UV–Vis, the latter resulting from pyrene localised emission (λ_em = 390 nm), the former from pyrene-sensitised emission of the lanthanide ion (λ_ex = 337 nm). Time-resolved measurements in the near-IR indicated that the number of coordinated solvent molecules for Nd and Yb was <1, confirming the proposed coordination mode of the octadentate L^pyr. The suitability of pyrene as a sensitiser for near-IR emitting lanthanides was further demonstrated in the rare observation of Er^III emission in a non-deuteriated protic medium.     

Structural studies of mono(pentamethylcyclopentadienyl)lanthanide complexes

The mono(pentamethylcyclopentadienyl) lanthanide complexes [(C₅Me₅)Yb(μ-I)(μ-η ⁵?: η ⁵-C₅Me₅)Yb(C₅Me₅)]_n (1), {[(C₅Me₅)Sm]₃(μ-Cl)₄(μ ₃-Cl)(μ ₃-OH)(THF)}₂ (2), {[(C₅Me₅)Sm]₂ (μ-OH)(μ-Cl)₄(μ ₃-Cl)Mg(THF)₂}₂ (3), [(C₅Me₅)₂Sm](μ-Cl)₆(μ ₃-Cl)₂(μ ₄-Cl)[(C₅Me₅)Sm]₄ (4), {[(C₅Me₅)Nd]₃(μ ₃-Cl)₄(μ ₄-Cl)₂(μ ₃-O₂CPh)₂K₂(η ⁶-C₇H₈)}₂ (5), [(C₅Me₅)Nd(C₈H₈)]₂(μ-dioxane) (6), [(C₅Me₅)Yb(MeO^tBu)]₂(μ-η ⁸?:?η ⁸-C₈H₈) (7), [(C₅Me₅)Dy(μ-I)₂]₃ (8), and [(C₅Me₅) Tm(MeCN)₆]I₂ (9), have been identified by X-ray crystallography. 1 is unusual in that it has a μ-η ⁵?:?η ⁵-C₅Me₅ ring that generates a local bent metallocene environment around ytterbium. Complexes 2–5 demonstrate the versatility of bridging chlorides in generating a variety of structures for mono(pentamethylcyclopentadienyl) lanthanide halides. Complex 6 shows how dioxane can generate a crystallographically-analyzable complex by bridging two mixed-ligand metallocene units that do not readily crystallize with THF. The structure of 7 shows how methyl tert-butyl ether (MTBE) ligates a lanthanide. Complex 8 is a trimeric cyclopentadienyl lanthanide halide unusual in that it has six bridging halides that roughly define a trigonal prism. Complex 9 constitutes an organometallic example of a lanthanide in which acetonitrile completely displaces iodide counterions.     

Synthesis,characterization, and biological activity of some lanthanide ternary complexes

Five complexes have been synthesized by the reaction of lanthanide(III) nitrate with 2-thenoyltrifluoroacetone (HTTA) and p-hydroxybenzoic acid (L). The complexes have been characterized by elemental analysis, molar conductivity, FT-IR, UV-Vis, ¹H NMR, TG-DTA, XPS, and transmission electron microscope. The general formula of the complexes is Na[Ln(TTA)₃L] (Ln?=?La³⁺,?Ce³⁺,?Nd³⁺,?Eu³⁺,?Er³⁺). The antibacterial activities indicate that all five complexes exhibit antibacterial ability against Escherichia coli and Staphylococcus aureus with broad antimicrobial spectrums. The antitumor activity of the five complexes against K562 tumor cell in vitro is measured using methyl thiazolyl tetrazolium (MTT) colorimetry. The results show that the complexes induce K562 tumor cell apoptosis, and the complexes exhibit inhibitory effect on leukemia K562 cells.     

Far-infrared and Raman spectra ofpseudo-tetrahedral complexes of ethylenedimorpholene

Summary The far-i.r. and Raman spectra of a closely related group ofpseudo-tetrahedral complexes of general formula [MX₂EDM] are reported (M = Co^II, Ni^II, Cu^II, Zn^II; X = Cl or Br). EDM, ethylenedimorpholene, acts in these compounds as a bidentate nitrogen donor. The main skeletal vibrations are assigned under the approximate symmetry of theC _2v (MX₂Y₂) point group.     

Synthesis,characterization and fluorescence of lanthanide Schiff-base complexes

Six new lanthanide Schiff-base complexes were synthesized by reactions of hydrated lanthanide nitrates with H₂L (H₂L?=?N,N′-bis(salicylidene)-1,2-cyclohexanediamine) and characterized by elemental analysis, DTA–TG, IR, UV and luminescence spectra. The microanalyses and spectroscopic analyses indicate a 1D polymeric structure with the formula of [Ln(H₂L)(NO₃)₃(MeOH)₂] _n [Ln?=?La (1), Ce (2), Pr (3), Sm (4), Gd (5) & Dy (6)]. The fluorescence spectrum of complex 4 exhibited Sm³⁺ centered, Schiff-base sensitized orange fluorescence, indicating that energy levels of the triplet state of H₂L match closely to the lowest excited state (⁴G_5/2) of Sm³⁺ ion.     

Energy transfer in solution of lanthanide complexes

The lanthanides with their well-defined energy levels provide an excellent basis to study different Ln(III)-specific energy transfer processes in a variety of chemical environments. The studies concerning intramolecular and intermolecular energy transfer processes with participation of Ln(III) ions and a variety of ligand groups in solution are reviewed. Phenomena of energy transfer from ligands to Ln(III) ions, resulting consequently in a great enhancement of the Ln(III) ion luminescence (ligand sensitized luminescence), as well as from Ln(III) to other species and between Ln(III) ions are presented.     

环戊二烯基轻稀土二氯化物邻菲罗啉配合物的合成

用LnCl~3邻菲绕啉和C~5H~5Na在四氢呋喃中的反应合成了四个1,10-二氮杂菲配位的含四氢呋喃的轻稀土环戊二烯二氯化物。用元素分析、红外光谱、电子能谱、差热分析等方法鉴定了这四个新化合物。     

Infrared spectra of lanthanide complexes with eriochrome cyanine r

An infrared spectroscopic study of the composition of these complexes in the solid state is described. Evaluation of the spectra made it possible to distinguish changes in the character of the lanthanide—ligand bonds in the series La — Lu, and to study the “double-double” effect.     

Compositional variations in monomeric trimethylsilylated allyl lanthanide complexes

Treatment of three equivalents of the potassium salt of the bis(1,3-trimethylsilyl)allyl anion with various late lanthanide triflates (M = Dy, Ho, Er, Tm, Lu) produces the unsolvated triallyllanthanide complexes (A′ = 1,3-(SiMe₃)₂C₃H₃). The use of lanthanide halides (Cl, I) with the potassium allyl also generates neutral complexes, but when lanthanide iodides and the corresponding lithium allyl are combined, the lanthanate species are formed. Trends in the bonding of lanthanide allyl complexes with the trimethylsilylated-allyl ligand are explored and compared with those of cyclopentadienyl lanthanide complexes.     

Different crystal structure and photophysical properties of lanthanide complexes with 5-bromonicotinic acid

Five novel lanthanide (Eu³⁺ (1), Tb³⁺ (2), Sm³⁺ (3), Dy³⁺ (4) and Gd³⁺ (5)) complexes with 5-Bromonicotinic acid (5-Brnic) were synthesized and two of them (Tb³⁺, Sm³⁺) were characterized by X-ray diffraction. The results reveal that {[Tb(5-Brnic)₃(H₂O)₃]·H₂O}_n (2) and [Sm(5-Brnic)₃(H₂O)₂·H₂O]₂ (3) exhibit different coordination geometries and crystal structures. Complex 2 has a one-dimensional chain-like polymeric structure through the bridged 5-Brnic anions which links up two neighboring terbium ions, while Complex 3 forms a dimeric molecular structure. The lowest triplet state energy of 5-Brnic was determined to be 24 330 cm⁻¹ corresponded to the 0-0 transition in the phosphorescence spectrum of its gadolinium complex at 411 nm. The strong luminescent emission intensities of these complexes indicated that the triplet state energy of 5-Brnic is suitable for the sensitization of luminescence of Eu³⁺, Tb³⁺, Sm³⁺ and Dy³⁺, especially for that of Tb³⁺ and Dy³⁺.