Luminescense properties of new complexes of Eu(III) and Tb(III) with heterotopic ligands

As a result of coordination between ligands L and L' and europium(III) and terbium(III) ions, the new architectures were formed. The formulae of the complexes have been assigned on the basis of the spectroscopic data in solution and microanalyses. The europium complexes show excellent luminescence properties with high quantum yield (1b-Eu(3)L(2)) and effective intramolecular energy transfer from the ligand to the Eu(III) ions.     

Synthesis,structure and olefin polymerization catalysis of nickel(II) complexes bearing N,O-chelate ligands

Four β-ketoimine ligands (two series) were prepared through traditional condensation reactions of β-diketones with 2,6-substituted anilines. Reaction took place only at the cyclohexanone carbonyl rather than at the acetyl or benzoyl carbonyl, even if more than two equivalents of the amines were added. Consequently, four new moisture- and air-stable bis(β-ketoamino)nickel(II) complexes, Ni[2–CH₃C(O)C₆H₈(=NAr)]₂ (Ar?=?2, 6-iPr₂C₆H₃, (1); Ar?=?2, 6-Me₂C₆H₃, (2) and Ni[2–PhC(O)C₆H₈(=NAr)]₂ (Ar?=?2, 6-iPr₂C₆H₃, (3); Ar?=?2, 6-Me₂C₆H₃, (4) were obtained and characterized. The solid-state structures of complex 1, 2 and 3 have been determined by single-crystal X-ray diffraction. Additionally, these complexes can be applied as highly active catalyst precursors for vinyl polymerization of norbornene (NBE) after activation with methylaluminoxane (MAO).     

Spectral properties of new N,N'-bis-alkyl-1,4,6,8-naphthalenediimide complexes

The photophysical properties of two N,N'-bis-alkyl-1,4,6,8-naphthalenediimide (DCN1 and DCN2) have been studied in chloroform and N,N-dimethylformamide solvents. The ability of DCN2 in N,N-dimethylformamide to detect metal cations have been monitored by the fluorescence emission spectroscopy. It has been shown that the fluorescent intensity is very sensitive to the concentration of Fe3+ cations. The reaction of iodine with N,N'-bis-alkyl-1,4,6,8-naphthalenediimide in chloroform solution have been investigated by spectrophotometric method. The results indicate the formation of two CT-complexes [(DCN1)I]+.I3- and [(DCN2)I]+.I3- at donor:acceptor molar ratio of 1:2. The [(DCN1)I]+.I3- shows the characteristic absorptions of I3- ion at 290 and 360 nm while the charge-transfer transition of [(DCN2)I]+.I3- occurs at 310 nm. Three characteristic bands at the far infrared region in each iodine complex are observed around 135, 105 and 85 cm-1 due to nuas (I-I), nus (I-I) and delta (I3-), respectively with C2v symmetry. The values of the complex formation constant, K, and the absorptivity, epsilon have been calculated.     

Pyridine-carboxylate complexes of platinum. Effect of N,O-chelate formation on model bifunctional DNA-DNA and DNA-protein interactions

This paper reports on the chemistry of platinum complexes containing bidentate pyridine-carboxylate (pyAc = pyridin-2-yl-acetate and picEt = pyridine-2-ethylcarboxylate, ethylpicolinate) (N,O) ligands. The pyridine-2-acetate and ethylpicolinate ligands form six- and five-membered chelates, respectively, upon formation of the Pt-carboxylate bond. In all reactions with picEt with various platinum complex starting materials, spontaneous de-esterification of the pendant carboxylate ester occurs to give directly the chelates K[PtCl(2)(pic-N,O)]-trans-[Pt(pic-N,O)(2)] and SP-4,2-[PtCl(pic-N,O)(NH(3))] without any evidence of intermediates. The de-esterification is solvent dependent, and molecular modeling was used to explain this reaction. The reactions of the geometric isomers of [PtCl(pyAc-N,O)(NH(3))] with 5'-guanosine monophosphate, 5'-GMP, and N-acetyl-l-methionine, AcMet, were investigated by NMR spectroscopy. The objective was to ascertain by model chemistry the feasibility of formation of ternary DNA-Pt-protein adducts in biology. Model nucleotide and peptide compounds were formed in situ by chloride displacement giving [PtL(pyAc-N,O)(NH(3))](+) (L = 5'-GMP or AcMet). Competitive reactions were then examined by addition of the complementary ligand L. Sulfur displacement of coordinated 5'-GMP was slow. For SP-4,3-[Pt(AcMet)(NH(3))(PyAc-N,O)](+), a rapid displacement of the sulfur ligand by 5'-GMP was observed, giving SP-4,2-[Pt(5'-GMP-N7)(pyAc-N,O)(NH(3))](+).     

Synthesis,crystal structures and luminescent properties of two new Ln(III)-dicarboxylate (Ln=Eu,Tb) complexes exhibiting three dimensional networks

Two new coordination polymers, {[Eu₂(L₁)₃(H₂O)₂]?·?H₂O} _n (1), (Cu(II)?···?Cu(II), [Tb(H₂O)]₂(L₂)₃?·?4H₂O (2) (H₂L₁?=?succinic acid, H₂L₂?=?glutaric acid) have been hydrothermally synthesized and characterized by elemental analysis, IR, luminescence spectra and single crystal X-ray diffraction. The complexes are constructed by dicarboxylates bridging chains of edge-sharing EuO₈(H₂O) and TbO₈(H₂O) polyhedra to form 3D network structures. Complexes 1 and 2 exhibit intense red and green photoluminescence upon UV excitation in the solid state at room temperature.     

两个多酸基镧系(Eu、Tb)双膦酸酯配合物的合成、物化性质和太赫兹时域光谱

在乙腈和去离子水的混合溶剂中合成了2个新的多酸基镧系双膦酸酯配合物[Eu (L)₄]PW₁₂O₄₀·2CH₃CN (1)和[Tb (L)₃(H₂O)]PW₁₂O₄₀(2)(L=亚乙基二膦酸四乙酯),并通过单晶X射线衍射、元素分析、红外光谱、粉末X射线衍射、热重分析和太赫兹时域光谱对2个配合物的性质进行了表征,分析了配合物的晶体结构及分子间弱作用力,研究了配合物的发光等性能。单晶结构表明,配合物1是以Eu (Ⅲ)为中心、L为配体螯合形成的扭曲四方反棱柱结构。配合物2是以Tb (Ⅲ)为中心、L和H₂O为配体形成的扭曲单帽八面体结构。发光光谱表明配合物1和2所有的发射峰来源于金属内部的电荷迁移。此外,太赫兹时域光谱对配合物1和2的结构和发光的分析提供了帮助。     

Brilliant Sm, Eu, Tb, and Dy chiral lanthanide complexes with strong circularly polarized luminescence

The synthesis, characterization, and luminescent behavior of trivalent Sm, Eu, Dy, and Tb complexes of two enantiomeric, octadentate, chiral, 2-hydroxyisophthalamide ligands are reported. These complexes are highly luminescent in solution. Functionalization of the achiral parent ligand with a chiral 1-phenylethylamine substituent on the open face of the complex in close proximity to the metal center yields complexes with strong circularly polarized luminescence (CPL) activity. This appears to be the first example of a system utilizing the same ligand architecture to sensitize four different lanthanide cations and display CPL activity. The luminescence dissymmetry factor, g(lum), recorded for the Eu(III) complex is one of the highest values reported, and this is the first time the CPL effect has been demonstrated for a Sm(III) complex with a chiral ligand. The combination of high luminescence intensity with CPL activity should enable new bioanalytical applications of macromolecules in chiral environments.     

Eu3+和Tb3+冠醚配合物的合成、荧光性质及与DNA作用研究

合成了含联萘骨架的酰胺型开链冠醚配体及稀土苦味酸盐配合物RE(pic)3L[L=N,N-乙基,苯基-N’,N’-二苯基-1,1’-联萘-2,2’-二(氧杂乙酰胺),RE=Eu3+,Tb3+],通过元素分析、IR、TG-DTA和摩尔电导率对配合物进行组成和结构推测。荧光光谱表明:Eu3+配合物的荧光强度远大于Tb3+配合物,说明配体L的三重态能级与Eu3+的激发态能级匹配较好。通过光谱法和粘度法研究了配合物与DNA的作用方式为插入作用,求出了Eu3+,Tb3+配合物与DNA的结合常数分别为4.072×104L.mol-1,8.780×103L.mol-1,证明配合物与DNA的作用大小是Eu3+(pic)3LTb3+(pic)3L.     

Synthesis,characterization and luminescence properties of Eu(III) and Tb(III) complexes with novel pyrazole derivatives and 1,10-phenanthroline

Two novel pyrazole-derived ligands, 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)picolinic acid (CDPA) and 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenylpicolinamide (CDPP) were prepared by 3,6-dichloropicolinic acid (DCPA). Their complexes with terbium(III) and europium(III) were synthesized. The complexes were characterized by elemental analysis, infrared spectra, ¹H NMR and TG–DTG. Furthermore, the above complexes using 1,10-phenanthroline as a secondary ligand were also synthesized and characterized. The luminescence properties of these complexes in solid state were investigated. The results suggested that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes and the fluorescence of the complexes with 1,10-phenanthroline as a secondary ligand was prominently stronger than that of complexes without this ligand., and the three ligand (DCPA), (CDPP) and (CDPA) are excellent sensitizers to Eu(III) and Tb(III) ion.     

Hydrothermal synthesis, crystal structures and luminescent properties of two new Ln(III)–succinate (Ln=Eu, Tb) complexes exhibiting three dimensional networks

Two new coordination polymers, [Eu₂(L)₃(H₂O)₂]_n 1 and {[Tb₂(L)₃(H₂O)₂]·H₂O}_n 2, (H₂L=succinic acid) have been synthesized by the reaction of H₂L with nitrate salts of Eu(III) or Tb(III) under hydrothermal conditions. The X-ray diffraction analysis reveals that the two complexes are constructed by L bridging the chains of edge-sharing EuO₈(H₂O) or TbO₈(H₂O) polyhedra to form 3D network structure. 1 and 2 possess different topological structures due to the difference in the conformations of L. The solid photoluminescence of 1 and 2 was also investigated in room temperature.     

Synthesis of Eu(III) and Tb(III) complexes with novel pyridine dicarboxamide derivatives and their luminescence properties

A novel ligand, N2,N6-bis[2-(3-methylpyridyl)]pyridine-2,6-dicarboxamide (L2) and the corresponding Eu(III) and Tb(III) hydrochlorate complexes have been synthesized and characterized in detail based on elemental analysis, IR and NMR. The crystal and molecular structure of the complexes was determined by X-ray crystallography. The Eu(III) and Tb(III) ions were found to coordinate to the amido nitrogen atoms and pyridine nitrogen atoms. The luminescence properties of lanthanide complexes in solid state, in different solutions and in different pH value were investigated. The result shows that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes, and the ligand (L2) is an excellent sensitizer to Tb(III) ion.     

Thermochemical properties of the rare earth complexes with pyromellitic acid

Fourteen rare earth complexes with pyromellitic acid were synthesized and characterized by means of chemical and elemental analysis, and TG–DTG. The constant-volume combustion energies of complexes, Δ_cU, were measured by a precise rotating-bomb calorimeter (RBC-type II). Their standard molar enthalpies of combustion, , and standard molar enthalpies of formation, , were calculated at T = 298.15 K. The relationship of and with the atomic numbers of the elements in the lanthanide series was examined. The results show that a certain amount of covalence is present in the chemical bond between rare earth cations and the ligand.     

A new BaB2Si2O8:Eu/Eu, Tb phosphor - Synthesis and photoluminescence properties

In the present work, we have synthesized maleevite mineral phase BaB₂Si₂O₈ for the first time, which is isostructural with the pekovite mineral SrB₂Si₂O₈. In these europium doped host lattices, we observed the partial reduction of Eu³⁺ to Eu²⁺ at high temperature during the synthesis in air. Tb³⁺ co-doping in MB₂Si₂O₈:0.01(Eu³⁺/Eu²⁺) [M=Sr, Ba] improves the emission properties towards white light. The emission color varies from bluish white to greenish white under UV lamp excitation when the host cation changes from Sr to Ba.     

Columinescence effect in macromolecular complexes of Eu(III) and Tb(III)

The effect of Y(III) and Gd(III) coactivator ions on the intensity of Eu(III) and Tb(III) luminescence in monomer and polymer mixed-metal complexes was studied. Isomorphic replacement of Eu(III) and Tb(III) ions by Y(III) and Gd(III) ions in macromolecular complexes led to sensitization of Eu(III) and Tb(III) ion luminescence. A mechanism of columinescence was suggested. It involves a charge transfer and the ligand orbitals and the vacant orbitals of Eu(III) and Tb(III) ions and coactivators.     

Synthesis of Eu(III) and Tb(III) complexes with novel pyridine dicarboxylic acid derivatives and their fluorescence properties

Starting from pyridine-2,6-dicarboxylic acid (DPA), a series of novel pyridine-2,6-dicarboxylic acid derivatives were synthesized. In these compounds, 4-(hydroxymethyl)pyridine-2,6-dicarboxylate (4-HMDPA) and 4-[(bis-carboxymethyl-amino)-methyl]-pyridine-2,6-dicarboxylic acid (4-BMDPA) were used as multifunctional ligands to coordinate with Tb(III) and Eu(III) and the complexes were prepared. The fluorescence properties of the solid complexes and their solutions were investigated in detail. The results indicated that the weak election-withdrawing group 4-hydroxymethyl in 4-position of pyridine in 4-HMDPA could weaken the fluorescence intensity of the lanthanide complexes. The contradistinctive experimental results showed that the fluorescence intensities of these complexes are related to pH values of the aqueous solutions and the dipole moments of solvent molecules: in the neutral aqueous solutions, the fluorescence intensities of these complexes were strongest, while the dipole moments were lower when the fluorescence intensities were stronger. 4-BMDPA is the better sensitizer and may be used as time-resolved fluoroimmunoassay. __________ Translated from Chemical Journal of Chinese Universities, 2006, 27(3) (in Chinese)     

Group I cation templated formation of luminescent mono- and bis-substituted thionaphthol heterobimetallic complexes of Pr, Nd, Eu and Tb

Metathesis of lanthanide tris di-tert-butyl beta-diketonates ([Ln(thd)3] Ln=Pr, Nd, Eu, Tb) with one or two equivalents of group 1 salts of the sulfur bridged binaphtholate dianion [1,1'-S(2-OC10H4But(2)-3,6)2]2-, [M2L], M=K, Li affords luminescent mono- and bis-ligand substituted complexes ML[LnL(thd)2].L; M=K, Ln=Pr , Nd , Eu and Tb (L=thf, diethyl ether or toluene) and M(thf)2[LnL2(thd)]; M=Li, Ln=Pr , Nd , Eu , Tb . The potassium salt [K2L] affords mono-L substituted complexes most cleanly, while the lithium salt [Li2L] yields the bis-L substituted complexes most cleanly. The L ligands function as antenna for the sensitised lanthanide-centred emission in Eu3+ and Tb3+ complexes. The X-ray single-crystal structures of mono- and bis-L lanthanide complexes of Nd3+ are presented.     

2,2'-bipyridine lariat calixcrowns: a new class of encapsulating ligands forming highly luminescent Eu3+ and Tb3+ complexes

A new class of calix[4]arene crown ethers with one or two bipyridines appended to the polyether ring (lariat calixcrowns) have been designed and synthesized; the luminescence properties of their Eu3+ and Tb3+ complexes have been studied in acetonitrile. In this solvent, long lifetimes for the metal emitting states and high metal-luminescence intensities obtained upon ligand excitation have been observed in both Eu3+ and Tb3+ complexes. The association constants in methanol have been determined for some of the complexes studied.     

Luminescence tuning of imidazole-based lanthanide(III) complexes [Ln = Sm, Eu, Gd, Tb, Dy

To tune the lanthanide luminescence in related molecular structures, we synthesized and characterized a series of lanthanide complexes with imidazole-based ligands: two tripodal ligands, tris{[2-{(1-methylimidazol-2-yl)methylidene}amino]ethyl}amine (Me(3)L), and tris{[2-{(imidazol-4-yl)methylidene}amino]ethyl}amine (H(3)L), and the dipodal ligand bis{[2-{(imidazol-4-yl)methylidene}amino]ethyl}amine (H(2)L). The general formulas are [Ln(Me(3)L)(H(2)O)(2)](NO(3))(3)·3H(2)O (Ln = 3+ lanthanide ion: Sm (1), Eu (2), Gd (3), Tb (4), and Dy (5)), [Ln(H(3)L)(NO(3))](NO(3))(2)·MeOH (Ln(3+) = Sm (6), Eu (7), Gd (8), Tb (9), and Dy (10)), and [Ln(H(2)L)(NO(3))(2)(MeOH)](NO(3))·MeOH (Ln(3+) = Sm (11), Eu (12), Gd (13), Tb (14), and Dy (15)). Each lanthanide ion is 9-coordinate in the complexes with the Me(3)L and H(3)L ligands and 10-coordinate in the complexes with the H(2)L ligand, in which counter anion and solvent molecules are also coordinated. The complexes show a screw arrangement of ligands around the lanthanide ions, and their enantiomorphs form racemate crystals. Luminescence studies have been carried out on the solid and solution-state samples. The triplet energy levels of Me(3)L, H(3)L, and H(2)L are 21?000, 22?700, and 23?000 cm(-1), respectively, which were determined from the phosphorescence spectra of their Gd(3+) complexes. The Me(3)L ligand is an effective sensitizer for Sm(3+) and Eu(3+) ions. Efficient luminescence of Sm(3+), Eu(3+), Tb(3+), and Dy(3+) ions was observed in complexes with the H(3)L and H(2)L ligands. Ligand modification by changing imidazole groups alters their triplet energy, and results in different sensitizing ability towards lanthanide ions.