Synthesis, structure, and catalytic activity of organolanthanides with chiral biphenyl-based tridentate amidate ligands

Four new chiral organolanthanide amidate complexes have been readily prepared in good yields via silylamine elimination reaction between Ln[N(SiMe₃)₂]₃ (Ln = Sm, Y, Yb) and chiral amidate ligands, (R)-2-(mesitoylamino)-2′-methoxy-6,6′-dimethyl-1,1′-biphenyl (1H) and (R)-2-(mesitoylamino)-2′-dimethylamino-6,6′-dimethyl-1,1′-biphenyl (2H). The steric effect of the ligand coupled with the size effect of the lanthanide ion plays an important role in complex formation. For example, treatment of 1H with half equiv of Sm[N(SiMe₃)₂]₃ gives the C₂-symmetric bis-ligated amidate complex (σOMe:κO:κN-1)₂SmN(SiMe₃)₂ (3) in 75% yield, while reaction of 1H or 2H with half equiv of Ln[N(SiMe₃)₂]₃ (Ln = Y, Yb) affords the C₁-symmetric bis-ligated amidate complexes [(κO:κN-1)(σOMe:κO:κN-1)]LnN(SiMe₃)₂ (Ln = Y (4), Yb (5) and the C₁-symmetric mono-ligated amidate complex (σNMe₂:κO:κN-2)Y[N(SiMe₃)₂]₂ (6), respectively, in good yields. These organolanthanide amidate complexes have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. They are active catalysts for asymmetric hydroamination/cyclization of aminoalkenes and ring-opening polymerization of rac-lactide, affording cyclic amines in excellent conversions with good ee values and isotactic-rich polylactides, respectively.     

Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with heterocyclic-functionalized fluorenyl ligands

Two series of new organolanthanide(II) complexes with tetrahydro-2H-pyranyl- or N-piperidineethyl-functionalized fluorenyl ligands were synthesized via one-electron reductive elimination reaction. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ with 2 equiv. of C₅H₉OCH₂C₁₃H₉ (1) or C₅H₁₀NCH₂CH₂C₁₃H₉ (2), respectively, in toluene at about 80 °C produced, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-C₅H₉OCH₂C₁₃H₈]₂Ln^II (Ln = Yb (3), Ln = Eu (4)) and [η⁵:η¹-C₅H₁₀NCH₂CH₂C₁₃H₈]₂Ln^II (Ln = Yb (5), Ln = Eu (6)) in good yields. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 3, 4, and 6 were additionally determined by single-crystal X-ray analyses. It represents the first example of solvent-free organolanthanide(II) complexes with fluorenyl ligands. The catalytic properties of the organolanthanide(II) complexes on the polymerization of ε-caprolactone and methyl methacrylate have been studied. The temperatures, solvents and coordination effects on the catalytic activities of the complexes were examined.     

New complexes of lanthanide Ln(III), (Ln = La, Sm, Gd, Er) with Schiff bases derived from 2-furaldehyde and phenylenediamines

Some new Schiff bases derivates from 2-furaldehyde and phenylenediamines (L^1-3) and their complexes with lanthanum (La), samarium (Sm), gadolinium (Gd) and erbium (Er) have been synthesized. These complexes with general formula [Ln(L^1-3)₂(NO₃)₂]NO₃·nH₂O (Ln = La, Sm, Gd, Er) were characterized by elemental analysis, UV-Vis, FT-IR and fluorescence spectroscopy, molar conductivity and thermal analysis. The metallic ions were found to be eight coordinated. The emission spectra of these complexes indicate the typical luminescence characteristics of the Sm(III), La(III), Er(III) and Gd(III) ions.     

Synthesis, crystal structure of bis(arylamido)lanthanide methyl complexes and their catalytic behavior for the polymerization of methyl methacrylate

Reactions of [N(C₆H₃i-Pr₂-2,6)(SiMe₃)]₂LnCl(THF) (Ln=Nd, Yb) with two equivalents of MeLi in a mixture solution of toluene and Et₂O gave [N(C₆H₃i-Pr₂-2,6)(SiMe₃)]₂LnCH₃(μ-CH₃)Li(THF)₃·PhCH₃ (Ln=Nd (1), Yb (2)) in good isolated yields as crystalline solids. The single-crystal structural analysis of 2 revealed that the coordination geometry of ytterbium ion is best described as a distorted pseudo-tetrahedron. Both 1 and 2 are active for the polymerization of methyl methacrylate to give syndiotactic-rich and high molecular weight polymers (M_n>10⁴) with relatively narrow molecular weight distributions (M_w/M_n<2).     

Synthesis,characterization and cytotoxic/cytostatic activity of Sm(III) and Gd(III) complexes

New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages.     

Homolysis of the Ln-N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with furfuryl- and tetrahydrofurfuryl-functionalized indenyl ligands

A series of new organolanthanide(II) complexes with furfuryl- and tetrahydrofurfuryl-functionalized indenyl ligands were synthesized via one-electron reductive elimination reaction. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) with 2 equiv. of C₄H₇OCH₂C₉H₇ (1) or C₄H₃OCH₂C₉H₇ (2), respectively in toluene at moderate high temperatures produced, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-(C₄H₇OCH₂C₉H₆)]₂Ln^II (Ln = Yb (5), Ln = Eu (6)) and [η⁵:η¹-(C₄H₃OCH₂C₉H₆)]₂Ln^II (Ln = Yb (7), Ln = Eu (8)) in reasonable to good yields. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) with 2 equiv. of C₄H₇OCH₂C₉H₆SiMe₃ (3) or C₄H₃OCH₂C₉H₆SiMe₃ (4), respectively, in toluene at moderate high temperatures afforded, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-(C₄H₇OCH₂C₉H₅SiMe₃)]₂Ln^II (Ln = Yb (9), Ln = Eu (10)) and[η⁵:η¹-(C₄H₃OCH₂C₉H₅SiMe₃)]₂Ln^II (Ln = Yb (11), Ln = Eu (12)) in good to high yields. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structure of complex 9 was additionally determined by single-crystal X-ray analyses. Studies on the catalytic activities of complexes showed that the complexes having silyl group functionalized indenyl ligands have high catalytic activities on ε-caprolactone polymerization. The temperatures, substituted groups on the indenyl ligands of the complexes, and solvents effects on the catalytic activities of the complexes were examined.     

Homolysis of the Ln-N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with 2-pyridylmethyl and 3-pyridylmethyl-functionalized indenyl ligands

Two series of new organolanthanide(II) complexes with general formula {η⁵:η¹-[1-R-3-(2-C₅H₄NCH₂)C₉H₅]}₂Ln(II) (R = H-, Ln = Yb (3), Eu (4); R = Me₃Si-, Ln = Yb (5), Eu (6)), and {η⁵:η¹-[1-R-3-(3-C₅H₄NCH₂)C₉H₅]}₂Ln(II) (R = H-, Ln = Yb (9), Eu (10); R = Me₃Si-, Ln = Yb (11), Eu (12)) were synthesized by silylamine elimination with one-electron reductive reactions of lanthanide(III) amides [(Me₃Si)₂N]₃Ln(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) with 2 equiv. 1-R-3-(2-C₅H₄NCH₂)C₉H₆ (R = H (1), Me₃Si- (2)) or 1-R-3-(3-C₅H₄NCH₂)C₉H₆ (R = H (7), Me₃Si- (8)) in good yields. All the complexes were fully characterized by elemental analyses and spectroscopic methods. Complexes 3 and 5 were additionally characterized by single-crystal X-ray diffraction study. The catalytic activities of the complexes for MMA polymerization were examined. It was found that complexes with 3-pyridylmethyl substituent on the indenyl ligands could function as single-component MMA polymerization catalysts with good activities, while the complexes with 2-pyridylmethyl substituent on the indenyl ligands cannot catalyze MMA polymerization. The temperatures and solvents effect on the MMA polymerization have also been examined.     

Synthesis,structure and antimicrobial study of two new copper(II) complexes derived from N-(3-aminopropyl) benzylamine ligand (apba) and N-salicylidene-apba

Two new copper(II) complexes were synthesized by reaction of N-(3-aminopropyl)benzylamine (L1: apba, for complex 1) and N-salicylidene-apba (L2: for complex 2) with Cu²⁺. Crystals of complex 1 were orthorhombic, space group pccn, with a?=?15.2149(10), b?=?25.0071(16), c?=?7.6280(5)?Å and α?=?β?=?γ?=?90°. Complex 2 crystals were monoclinic, space group P2₁/c, with a?=?8.688(6), b?=?12.812(9), c?=?16.022(11)?Å and β?=?99.241(10)°. Structures of the two complexes were centro-symmetric and both Cu(II) atoms were four coordinate with a distorted square-planar geometry. The toxicity of the complexes was evaluated by testing antimicrobial activity against bacterial strands.     

Bridged bis(amidinate) lanthanide complexes: Synthesis,molecular structure and reactivity

The yttrium chloride with the bridged bis(amidinate) L (L = Me₃SiNC(Ph)N(CH₂)₃NC(Ph)NSiMe₃) LYCl(DME) (2) was synthesized and structurally characterized. Treatment of LLnCl(sol)_x (Ln = Yb, sol = THF, x = 2 1; Ln = Y, sol = DME, x = 1 2) with the dilithium salt Li₂L(THF)_0.5 afforded the novel bimetallic lanthanide complexes supported by three ligands, Ln₂(μ₂-L)₃ · DME (Ln = Yb 3, Y 4; DME = dimethylether), instead of the designed complex LLn(μ₂-L)LnL via the ligand redistribution reaction. Complexes 3 and 4 were fully characterized including X-ray analysis and ¹H NMR spectrum for 4. Reaction of LnCl₃ (Ln = Yb, Y) with 2 equiv. of Li₂L(THF)_0.5 gave the anionic complexes [Li(DME)₃][L₂Ln] (Ln = Yb 5, Y 6), which were confirmed by a crystal structure determination. The further study indicated that complexes 3 and 4 can also be synthesized by reaction of LnCl₃ (Ln = Yb, Y) with 1.5 equiv. of Li₂L(THF)_0.5 or reaction of 1 and 2 with anionic complexes 5 and 6. Complexes 3, 4, 5 and 6 were found to be high active catalysts for ring-opening polymerization of ε-caprolactone (CL).     

Investigation of 5-chloro-2-methoxybenzoates of La(III), Gd(III) and Lu(III) Complexes

5-Chloro-2-methoxybenzoates of La(III), Gd(III) and Lu(III) were synthesized as penta-, mono- and tetrahydrates with a metal to ligand ratio of 1:3 and with white colour typical of La(III), Gd(III) and Lu(III) ions. The complexes were characterized by elemental analysis, IR and FIR spectra, thermogravimetric and diffractometric studies. The carboxylate group appears to be a symmetrical, bidentate, chelating ligand. The complexes are polycrystalline compounds. Their thermal stabilities were studied in air and inert atmospheres. When heated they dehydrate to form anhydrous salts which next in air are decomposed through oxychlorides to the oxides of the respective metals while in inert atmosphere to the mixture of oxides, oxychlorides of lanthanides and carbon. The most thermally stable in air, nitrogen and argon atmospheres is 5-chloro-2-methoxybenzoate of Gd(III). This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,characterization, and antioxidant activity of a new Gd(III) complex

A new gadolinium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in molar ratio of 1:3 to ligand. The structure of the complex was determined by elemental analysis, FT-IR, and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Gd(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygens. The newly synthesized gadolinium(III) complex of 5-aminoorotic acid (GdAOA) showed antioxidant properties. The antioxidant activity of both HAOA and GdAOA was related with their electron donor properties.     

Synthesis, structure, and catalytic activity of binuclear lanthanide complexes with chiral NOBIN-based NNO ligands

Two new amido binuclear complexes {(1)YN(SiMe₃)₂}₂ · C₇H₈ (3 · C₇H₈) and {(2)SmN(SiMe₃)₂}₂ · C₆H₁₄ (4 · C₆H₁₄) have been readily prepared in good yields by amine elimination reaction between Ln[N(SiMe₃)₂]₃ (Ln = Sm, Y) and chiral NNO ligands, (S)-2-(pyridin-2-ylmethylamino)-2′-hydroxy-1,1′-binaphthyl (1H₂) and (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl (2H₂), respectively. They both have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. They are active catalysts for asymmetric hydroamination/cyclization of aminoalkenes and ring-opening polymerization of rac-lactide, affording cyclic amines in excellent conversions with moderate ee values and isotactic-rich polylactides, respectively.     

Thermogravimetric and spectroscopic studies on La(III) and Ce(III) complexes with some thio-schiff bases

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 [ML₂(H₂O)X]·2H₂O, whereM=trivalent lanthanide ion,L=Schiff base andX=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.     

Complexes of Oxamic Acid with La(III), Gd(III), Tb(III), Er(III), Tm(III) and Lu(III)

The preparation, for the first time, of the deprotonated complexes of oxamic acid with La(III), Gd(III), Tb(III), Er(III), Tm(III) and Lu(III) is reported. Analytical results, conductometric measurements, magnetic moments and spectral data (IR and diffuse reflectance spectra) are discussed in terms of possible structural types. The oxamate anion acts as a N, O bidentate non-bridging ligand.     

Bis(imino)pyridine palladium(II) complexes: Synthesis, structure and catalytic activity

Bis(imino)pyridine palladium(II) complexes 3-6 were synthesized by two different methods. The structure of complexes 3 and 4 has been confirmed by X-ray structure analysis. The catalytic studies show that bis(imino)pyridine palladium(II) complexes are highly efficient catalysts in the Suzuki-Miyaura reaction and the complex 4 was used to catalyze the synthesis of fluorinated liquid crystalline compounds via Suzuki coupling reaction.     

Antimicrobial,antioxidant and antitumor activities of Nano-Structure Eu (III) and La (III) complexes with nitrogen donor tridentate ligands

Nano structure metal complexes of Eu (III) and La (III) with two different nitrogen donor tridentate ligands: N-(2-Aminoethyl)-1,3-propanediamine “AEPD = L1” and 1-(2-Aminoethyl)piperazine “AEPz = L2” , were prepared. All synthesized compounds were identified and confirmed by elemental analyses, molar conductivity and spectral analyses (UV–Visible, IR and mass). Conductance measurement indicates that all the complexes are non-electrolytic in nature and the complexes were isolated in 1:1 molar ratio (metal: ligand). Thermal decomposition profiles were consistent with the proposed formulations. The ligands behave as a tridentate ligand through three nitrogen centers of donation. The nano-size was investigated by using transmission electron microscopy (TEM). The geometric structure properties were analyzed using density functional theory (DFT) for ligands and their Lanthanum (III) complexes. The complexes were screened against some bacteria strains, hepatocellular cell line and diphenylhydrazine free radical. The molecular docking active sites interactions were evaluated.     

Synthesis,characterization and cytotoxicity of gold(III) complexes with deprotonated pyridyl carboxamide

Six new gold(III) complexes [Au(bzpam)Cl₂] (1, bzpamH = N‐benzyl picolinamide), [Au(hetpam)Cl₂] (2, hetpamH = N‐(2‐hydroxyethyl) picolinamide), [Au(pypam)Cl]AuCl₄ (3, pypamH = N‐(pyridin‐2‐ylmethyl) picolinamide), [Au(dmepam)Cl]AuCl₄ (4, dmepamH = N‐(2‐(dimethylamino)ethyl) picolinamide), [Au(bhetpydam)Cl] (5, bhetpydamH₂ = N,N′‐bis(2‐hydroxyethyl) pyridine‐ 2,6‐dicarboxamide) and [Au₂(hedam)Cl₄] (6, hedamH₂ = N,N′‐(hexane‐1,6‐diyl) dipicolinamide) with deprotonated pyridyl carboxamide were synthesized and characterized by elemental analysis, molar conductivity, IR, H¹ NMR and C¹³ NMR techniques. The analytical data showed that deprotonated pyridyl carboxamide coordinated with gold(III) ions through a nitrogen atom. The cytotoxicity against Bel‐7402 and HL‐60 cell lines was tested by MTT (3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) and SRB (sulforhodamine B) assays. The results indicated that the complexes exerted cytotoxic effects against Bel‐7402 and HL‐60 cell lines, complex 6 had better cytotoxicity than cisplatin, and complex 3 displayed similar cytotoxicity to cisplatin against Bel‐7402 cell line. The results suggested that the characteristics of ligands had an important effect on cytotoxicity of complexes. Copyright © 2012 John Wiley & Sons, Ltd.     

含联吡啶，Eu(III)或Gd(III)的手性高分子配合物的合成及荧光性质研究

手性高分子P–1由(R)-5,5′-二溴-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘(R–M–1)和5,5′-二乙烯基-2,2′-联吡啶(M–2)通过Pd催化的Heck偶合反应合成得到,高分子配合物P-2和P-3由高分子P-1与Eu(TTA)3·2H2O和Gd(TTA)3·2H2O (TTA– = 2-噻吩甲酰三氟丙酮)反应生成。手性高分子P-1能发射强的蓝色荧光,这是由于手性重复单元(R)-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘和单元2,2′-联吡啶通过亚乙烯基桥连形成共轭高分子结构造成的。在不同的激发波长激发下,含Eu(III)的高分子配合物P–2不仅显示高分子荧光,还可显示Eu(III) (5D0→7F2)特征荧光。含Gd(III)的高分子配合物P–3仅发射高分子荧光。基于高分子及含RE(III)的高分子配合物的荧光性质研究发现,共轭高分子并没有把能量转移到Eu(III)或Gd(III) 配合物部分,只发射它自身的荧光,含Eu(III)的高分子配合物P–2发射Eu(III) (5D0→7F2)特征荧光能量主要来源于配阴离子TTA–。     

Fluorescence of lanthanide(III) complexes with aminopolyacetic acids in aqueous solutions

The fluorescence of Eu(III), Gd(III), Tb(III) and Dy(III) ions complexed with aminopolyacetic acids was investigated. The influence of temperature and the dimensions of the ligand molecules and of their electric charge on the intensity of the emission bands is discussed as well as the ratio of the hypersensitive (forbidden) band to the allowed band intensity. On the basis of the fluorescence measurements a simple theoretical model is discussed and certain generalizations concerning the fluorescence of the lanthanides group are derived.

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Fluoreszenz von Lanthaniden(III)-Komplexen mit Aminopolyessigsäuren in wäßrigen Lösungen

Zusammenfassung Die Fluoreszenz von mit Aminopolyessigsäuren komplexierten Eu(III), Gd(III), Tb(III) und Dy(III) Ionen wurde untersucht. Der Einfluß von Temperatur und Größe der Ligandenmoleküle und von deren elektrischer Ladung auf die Intensität der Emissionsbanden wird diskutiert, ebenso das Verhältnis der Intensitäten der hyperempfindlichen und erlaubten Banden. Auf der Basis von Fluoreszenzmessungen wird ein einfaches theoretisches Modell diskutiert und Verallgemeinerungen betreffend der Fluoreszenz der Lanthanidengruppe getroffen.

     

甲基丙烯酸-8-羟基喹啉-镧配合物的合成及与DNA的作用

合成了配合物La(C4H6O2)2(hq)(C4H6O2=甲基丙烯酸,hq=8-羟基喹啉),通过元素分析、摩尔电导、红外光谱、紫外光谱和热重分析手段对产物进行表征。此外,采用紫外吸收光谱、荧光光谱,研究了配合物与鲱鱼精DNA之间的相互作用。结果显示配合物与鲱鱼精DNA作用的结合常数K=7.59×103L·mol-1,配合物与DNA的作用摩尔比为1∶1,作用模式为嵌插作用。