Studies on synthesis, infrared and fluorescence spectra of new europium (III) and terbium (III) complexes with an beta-diketonate-type ligand

A new beta-diketonate-type ligand, N-(2-amino-6-methyl-pyridinyl)ketoacetamide (L) and its complexes with europium (III) and terbium (III) were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium (III) and terbium (III)-ions were found to coordinate to the CO oxygen atoms and pyridine nitrogen atoms. The fluorescence properties of these complexes in solid, DMF and CH3OH were studied. The solvent factors influencing the fluorescent intensity are discussed.     

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.     

Synthesis and infrared and fluorescence spectra of new europium and terbium polynuclear complexes with an amide-based 1,10-phenanthroline derivative

An amide-based 1,10-phenanthroline (phen) derivative and its complexes with europium(III) and terbium(III) ions were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium and terbium ions were coordinated by O atoms of C=O, Ar-O-C and N atoms of phen. The fluorescence properties of the complexes in THF, dioxane, MeCN and DMF were investigated. Under the excitation of UV light, these complexes exhibited characteristic fluorescence of europium and terbium ions. The solvent factors influencing the fluorescent intensity were discussed.     

Simultaneous spectrophotometric determination of atrazine and cyanazine by chemometric methods

Three novel ligands containing pyridine-2,6-dicarboxylic acid unit, trans-4 -(4'-methoxystyryl) pyridine-2,6-dicarboxylic acid, trans-4-(4'-(dimethylamino)styryl)pyridine-2,6-dicarboxylic acid, and trans-4-(4'-(diphenylamino)styryl)pyridine-2,6-dicarboxylic acid were synthesized and their complexes with Eu(III), Tb(III) ions were successfully prepared. The ligands and the corresponding metal complexes were characterized by means of MS, elemental analysis, IR, (1)H NMR and TG-DTA. The luminescence spectra of Eu(III) and Tb(III) complexes in solid state were studied. The strong luminescence emitting peaks at 615 nm for Eu(III) and 545 nm for Tb(III) can be observed. The applications in cell imaging of the europium and terbium complexes were investigated.     

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.     

Luminescent properties of europium(III) and terbium(III) complexes with para- and ortho-ethoxybenzoic acids

The luminescent properties of europium(III) and terbium(III) complexes with para- and ortho-ethoxybenzoic acids are studied. The excitation energies of the triplet states of ligands are determined, a hypothesis is made about the efficient luminescence of europium(III) and terbium(III) complexes, the geometry of the coordination polyhedron of a europium complex is established, and the luminescence quantum yields of the complexes in solution are determined.     

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, structure, infrared and fluorescence spectra of new rare earth complexes with 6-hydroxy chromone-3-carbaldehyde benzoyl hydrazone

A novel 6-hydroxy chromone-3-carbaldehyde benzoyl hydrazone ligand and its four complexes, [LnL2(NO3)2]NO3 [Ln = Eu(1), Sm(2), Tb(3), Dy(4)], were synthesized. The complexes were characterized by the elemental analyses, molar conductivity and IR spectra. The crystal and molecular structure of Sm(III) complex was determined by single-crystal X-ray diffraction: crystallized in the triclinic system, space group P-1, Z = 1, a = 11.037(4) A, b = 14.770(5) A, c = 15.032(7) A, alpha = 60.583(4), beta = 75.528(7), gamma = 88.999(4), R1 = 0.0349. The fluorescence properties of complexes in the solid state and in the organic solvent were studied in detail, respectively. Under the excitation of ultraviolet light, strong red fluorescence of solid europium complex was observed. But the green fluorescence of solid terbium complex was not observed. These observations show that the ligand favor energy transfers to the emitting energy level of Eu3+. Some factors that influence the fluorescent intensity were also discussed.     

Peculiarities of the excitation energy transfer in europium and terbium aromatic carboxylates and nitrate complexes with sulfoxides: Blocking effect

The influence of modification of the aromatic ligands on the excitation energy transfer to Ln³⁺ ions in europium and terbium carboxylates and nitrates was examined. The luminescence excitation spectra of three groups of the europium and terbium compounds: phenyl-, diphenyl-, triphenylacetates, phenoxyacetates and triphenylpropionates; 1- and 2-naphthylcarboxylates and 2-naphthoxyacetates; lanthanide nitrates with diarylsulfoxides (diphenyl- and dibenzylsulfoxides) and dialkylsulfoxides were investigated. The spectra of adducts of terbium phenylcarboxylates with 1,10-phenanthroline were also analyzed. The effect of the aliphatic bridges, which decouple the π–π- or p–π-conjugation in the ligand, on the energy transfer to Ln³⁺ ions (so-called blocking effect) was investigated. It was shown, that this decoupling leads to significant lowering of the energy of “ligand–metal ion” charge transfer states (LM CTS) in the europium carboxylate salts, just down to 27,800 cm⁻¹ in europium 2-naphthoxyacetate. As a consequence, the probability of the LM CTS participation in the excitation energy dissipation processes increases. A channel of the excitation energy dissipation in the region of 31,750 cm⁻¹ related to ligand electronic transitions was found in the europium and terbium nitrates with sulfoxides. It was demonstrated that a part of the energy absorbed by the aromatic ligand having aliphatic bridge can be emitted as the ligand fluorescence.     

Synthesis and infrared and luminescence spectra of rare earth complexes with a new hexapodal ligand

Solid complexes of rare earth nitrates and picrates with a new hexapodal ligand, 1,2,3,4,5,6-hexa{[(2'-benzylamino-formyl)phenoxyl]methyl}-benzene (L) have been prepared. These complexes were characterized by elemental analysis, IR and molar conductivity. At the same time, the luminescence properties of the Eu(III) and Tb(III) nitrates and picrates complexes in solid state were also investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of europium and terbium ions. The influence of the counter anion on the luminescent intensity was also discussed.     

Synthesis and infrared and fluorescent properties of rare earth complexes with a new aryl amide podand

Solid complexes of rare earth nitrates and picrates with a new aryl amide podand, 1,4-bis{[(2'-benzylamino-formyl)phenoxyl]methyl}-naphthaline (L) were synthesized. The complexes were characterized by elemental analysis, IR and molar conductivity measurements. At the same time, the fluorescent properties of the Eu(III) and Tb(III) nitrates and picrates complexes in solid state were also investigated. Under the excitation, these complexes exhibited characteristic emissions of europium and terbium ions. The counter anion factor influencing the fluorescent intensity was also discussed.     

Comparative Analysis of Conjugated Alkynyl Chromophore–Triazacyclononane Ligands for Sensitized Emission of Europium and Terbium

A series of europium and terbium complexes based on a functionalized triazacyclononane carboxylate or phosphinate macrocyclic ligand is described. The influence of the anionic group, that is, carboxylate, methylphosphinate, or phenylphosphinate, on the photophysical properties was studied and rationalized on the basis of DFT calculated structures. The nature, number, and position of electron‐donating or electron‐withdrawing aryl substituents were varied systematically within the same phenylethynyl scaffold in order to optimize the brightness of the corresponding europium complexes and investigate their two‐photon absorption properties. Finally, the europium complexes were examined in cell‐imaging applications, and selected terbium complexes were studied as potential oxygen sensors.     

Synthesis and infrared and fluorescent spectra of rare earth complexes with a new amide ligand

Solid complexes of rare earth nitrates and picrates with a new amide ligand, 1,6-bis[(2'-benzylaminoformyl)phenoxyl]hexane (L) have been prepared. These complexes are characterized by elemental analysis, UV-vis spectra and IR spectra. The fluorescent and luminescent properties of the Eu(III) and Tb(III) nitrates and picrates complexes in solid state are also investigated. Under the excitation of UV light, these complexes except Tb(III) picrate complex exhibit characteristic emission of europium and terbium ions. The influence of the counter anion on the fluorescent intensity is also discussed.     

Studies on synthesis and infrared and fluorescence spectra of new europium and terbium complexes with an amide-based open-chain crown ether

An amide-based open-chain crown ether ligand and its complexes with europium and terbium were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium and terbium ions were found to coordinate to the C=O oxygen atoms and pyridine nitrogen atoms. The fluorescence properties of these complexes in DMF and CH3OH/CHCl3 were studied. Under the excitation of UV light, these complexes exhibit characteristic fluorescence of europium and terbium ions. The solvent factors influencing the fluorescent intensity are discussed.     

稀土配合物的发光机理和荧光分析特性研究(Ⅰ)——钐、铕、铽和镝配合物的发光机理

本文采用激光诱导荧光法研究了钐、铕、铽和镝配合物的化学性质、光谱特性与光谱能级间的关系,提出了稀土配合物荧光发射的能量传递模型,并导出速率方程和定态解,根据Dexter固体敏化发光理论讨论了影响荧光产率的各种因素,推导出配体三重态向稀土离子激发态进行有效能量传递的3个条件。     

Conformation effects on the fluorescence spectra of europium and terbium complexes with a family of ether-amide type multipodal ligands

Three multipodal ligands: 3,3,7,7-tetra[N-methyl-N-phenyl(acetamide)-2-oxymethyl]-5-oxanonane (La), 3,3,7,7-tetra[N-ethyl-N-phenyl(acetamide)-2-oxymethyl]-5-oxanonane (Lb), 3,3,7,7-tetra[N-benzyl-N-phenyl(acetamide)-2-oxymethyl]-5-oxanonane (Lc) and their europium and terbium nitrate and perchlorate complexes were synthesized. The 12 complexes were characterized by elemental analysis, IR, fluorescence spectroscopy and conductivity. The novel cup-like crystal structure of the Eu(III) complex with Lb and fluorescence emission properties of the complexes have also been studied. It has been showed that the nature of the anion has a great effect upon the composition of the complexes. The difference in the composition of the complexes results in the difference in the emission properties of them. The [Ln(NO3)5] group is negatively effective to the fluorescence intensity of the nitrate complexes. The luminescence intensity of Ln(III) perchlorate complex is stronger than that of nitrate complex.     

6-Phosphoryl picolinic acids as europium and terbium sensitizers

Three 6-phosphoryl picolinic acid (6PPA) derivatives were synthesized and used as europium and terbium sensitizers. Two of the three ligands (6-diethoxyphosphoryl picolinic acid (Hdeppa) and 6-monoethoxyphosphoryl picolinic acid (H(2)meppa)) are water-soluble, once complexed to lanthanide ions, while the third (6-dihydroxyphosphoryl picolinic acid (H(3)dhppa)) forms a precipitate. The stability constants of the phosphoryl-based complexes were found to be higher than the carboxylate analogue (dipicolinic acid, H(2)dpa). The main species are the [LnL(3)] complexes under strict stoichiometric conditions, confirmed by (31)P NMR spectroscopy, mass spectrometry and lifetime analyses. The photophysical measurements reveal that the emission intensity of [Eu(deppa)(3)] is maximal at pH 4.8, whereas for [Eu(meppa)(3)](3-), the optimum pH is observed at 9.0. The lifetimes are all in the millisecond range and have confirmed the absence of water molecules in the first coordination sphere. The emissions of the terbium are always brighter than the corresponding europium within this phosphoryl series. The quantum yields of the phosphoryl containing complexes are lower than the carboxylate analogue ([Ln(dpa)(3)](3-)), except for [Tb(deppa)(3)], which exhibits an interesting quantum yield of 40% in aqueous solution.     

Synthesis and infrared and fluorescence spectra of rare earth complexes with a novel amide-based ligand

A novel amide-based open-chain crown ether, N,N'-1,3-propanediyl-bis[2-(benzyl -carbamoyl-methoxy)-benzamide] (L) and its solid complexes with rare earth nitrates and picrates have been prepared. The complexes were characterized by elemental analyses, molar conductivity and IR spectra. The fluorescence properties of the Eu(III) and Tb(III) complexes in solid and in organic solvents were studied. Under the excitation of ultraviolet light, these complexes exhibit characteristic emission of europium and terbium ions. The results show that the ligand favor energy transfers to the emitting energy level of Tb(III). Some factors that influence the fluorescent intensity were also discussed.     

Innovative Multipodal Ligands Derived from Tröger's Bases for the Sensitization of Lanthanide(III) Luminescence

Herein, the synthesis and characterization of the first family of multipodal ligands with a Tröger's base framework designed for the preparation of luminescent lanthanide(III) complexes are reported. Eight ligands were designed and synthesized using different strategies, including alkylation reactions, amide couplings, and Ugi multicomponent reactions. All the ligands bear carboxylate groups for the coordination of the lanthanide(III) ions, with the lanthanide(III)-sensitizing units consisting of the Tröger's base framework itself or attached benzamides. Upon irradiation of the chromophoric ligands, green terbium(III) emission was efficiently generated, whereas europium(III) emission was negligible. The geometry and substitution pattern of the ligands allow control of the stoichiometry of the species formed and the Tb^III luminescence sensitization efficiency, showing that para-substitution patterns are more efficient than meta substitution for the formation of coordination compounds with lower Tb^III/ligand ratio. We propose that the species formed are self-assembled 2:2 or 2:4 metallosupramolecular structures.     

Efficient sensitization of europium, ytterbium, and neodymium functionalized tris-dipicolinate lanthanide complexes through tunable charge-transfer excited states

A series of push-pull donor-pi-conjugated dipicolinic acid ligands and related tris-dipicolinate europium and lutetium complexes have been prepared. The ligands present broad absorption and emission transitions in the visible spectral range unambiguously assigned to charge-transfer transitions (CT) by means of time-dependent density functional theory calculations. The photophysical properties (absorption, emission, luminescence quantum yield, and lifetime) of the corresponding europium complexes were thoroughly investigated. Solvatochromism and temperature effects clearly confirm that Eu(III) sensitization directly occurs from the ligand CT state. In addition, modulation of the energy of the CT donating state by changing the nature of the donor fragment allows the optimal energy of the antennae for europium sensitization to be determined, and this optimal energy was found to be close to the (5)D 1 accepting state. Finally, this CT sensitization process has been successfully extended to near-infrared emitters (neodymium and ytterbium).