The enhancement of luminescent properties of Tb3+ complexes with tetra-1,3-diketone ligands promoted by the tetrathiacalix[4]arene scaffold

This is the first report on the synthesis and characterization of tetra-1,3-diketone derivatives of tetrthia- and calix[4]arenes substituted by acetylacetonyl or dipivaloylmethanyl moieties at the upper rim and bearing hydroxyl groups at the lower rim as ligands for Tb³⁺ complexes. The spatial structure and tautomeric content for the synthesized ligands have been determined by means of X-ray, IR and NMR spectroscopy. Comparison of the sensitizing properties of tetrathiacalix[4]arenes and their calix[4]arene analogues on the Tb³⁺-centered luminescence in DMF solutions has been performed. A substantial enhancement of the luminescent properties of Tb³⁺- complexes with tetra-1,3-diketone ligands promoted by the tetrathiacalix[4]arene scaffold was established.     

Sensitization of Tb<Superscript>3+</Superscript> luminescence with polypyridyl ligands in a nafion membrane

Perfluorosulfonic membranes were modified by terbium(III) polypyridyl complexes by ionexchange sorption of cations followed by addition of ligands. The luminescence sensitization degree is compared with the state of ligands in the grafted complexes. In the case of the terbium(III) 4,7-diphenylphenanthroline complex, strong blue luminescence of the ligand is observed, along with radiation transitions of the cation. The character of luminescence quenching in modified membranes in a wet medium is determined by the ability of ligands to prevent terbium from adsorbing water molecules.     

Europium(III) and terbium(III) chelates of quinolonecarboxylic acid derivatives as labels for immunofluorimetric assay

Luminescence properties of Tb(III) and Eu(III) complexes of quinolonecarboxylic acid derivatives were studied. Optimal conditions of luminescence were determined, and the influence of surfactants and diethylenetriaminepentaacetic acid on the luminescence properties of the complexes was studied. It was demonstrated that species-specific immunoglobulins labeled with terbium ions can be determined with the detection limit of the lanthanide label 5 x 10^-14 M.     

Distribution of luminescence excitation energy between Eu<Superscript>3+</Superscript> and Tb<Superscript>3+</Superscript> ions fixed in a perfluorosulfonic membrane

Ion-exchange modification of MF-4SK perfluorosulfonic membranes with Eu³⁺ and Tb³⁺ cations was realized. The state of cations in the membrane was studied by X-ray photoelectron spectroscopy. Special features of the luminescence of the resulting systems point to preferential excitation energy transfer from europium to terbium.     

Design, synthesis, characterization, luminescence and non-linear optical (NLO) properties of multinuclear platinum(II) alkynyl complexes

A series of luminescent multinuclear platinum(II) alkynyl complexes containing triethynylbenzene or 1,4-bis(3,5-diethynylphenyl)buta-1,3-diyne as cores has been successfully synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption and electrochemical properties of these complexes have been reported. These complexes show long-lived emissions in degassed benzene solution and in alcoholic glass at 77 K. Moreover, they are found to exhibit two-photon absorption (2PA) and two-photon induced luminescence (TPIL) properties, and their two-photon absorption cross-sections have been determined to be 6-191 GM upon excitation at 720 nm. Through a systematic comparison, it has been found that tetra- and hexanuclear platinum(II) complexes show better 2PA and TPIL properties than their di- and trinuclear counterparts.     

IR Luminescence of Nd<Superscript>3+</Superscript>, Sm<Superscript>3+</Superscript>, and Yb<Superscript>3+</Superscript> β-Diketonates in Different Aggregate States

The influence of the aggregate state on the IR luminescence is studied for the Nd(III), Sm(III), and Yb(III) complexes with the thienyl, phenyl, and alkyl derivatives of acetylacetone in solutions and as sorbates on the polymer matrix. It is found that the luminescence intensity of the sorbates of the complexes is 2–3 orders of magnitude higher than that in solutions due to the elimination of diffusion and respective intermolecular nonradiative losses of the excitation energy.     

From chemistry to materials, design and photophysics of functional terbium molecular hybrids from assembling covalent chromophore to alkoxysilanes through hydrogen transfer addition

Two silica-based organic-inorganic hybrid materials composed of phenol (PHE) and ethyl-p-hydroxybenzoate derivatives (abbreviated as EPHBA) complexes were prepared via a sol-gel process. The active hydroxyl groups of PHE/EPHBA grafted by 3-(triethoxysilyl)-propyl isocyanate (TESPIC) through hydrogen transfer reaction were used as multi-functional bridged components, which can coordinate to Tb³⁺ with carbonyl groups, strongly absorb ultraviolet and effectively transfer energy to Tb³⁺ through their triplet excited state, as well as undergo polymerization or crosslinking reactions with tetraethoxysilane (TEOS), for anchoring terbium ions to the silica backbone. For comparison, two doped hybrid materials in which rare-earth complexes were just encapsulated in silica-based sol-gel matrices were also prepared. NMR, FT-IR, UV/vis absorption and luminescence spectroscopy were used to investigate the obtained hybrid materials. UV excitation in the organic component resulted in strong green emission from Tb³⁺ ions due to an efficient ligand-to-metal energy transfer mechanism.     

Luminescence determination of DNA using terbium complexes with 2-oxo-4-hydroxyquinoline-3-carboxylic acid amides as probes

It was found that the presence of DNA significantly enhanced the 4f luminescence of terbium(III) in its complexes with a number of 2-oxo-4-hydroxyquinoline-3-carboxylic acid amide derivatives (L₁-L₆). For the high-sensitivity determination of DNA, L₁ and L₄ were chosen from two proposed groups, in complexes with which terbium ions exhibited the most intense luminescence. Under optimum conditions, the luminescence intensity of terbium was proportional to the concentration of DNA over the ranges 0.025–1.2 μg/mL (detection limit of 10 ng/mL) and 0.01–1.2 λg/mL (detection limit of 3 ng/mL) for L₁ and L₄, respectively. The mechanisms of the interaction of Tb-L complexes with DNA molecules were hypothesized.     

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.     

Luminescent dinuclear lanthanide complexes of 5-Me-HXTA

The synthesis and characterization of a series of anionic homobimetallic lanthanide complexes of the septadentate chelate 5-Me-HXTA (N,N-(2 hydroxy-5-methyl-1,3-xylylene)bis(N-(carboxymethyl)glycine) is described (Ln = Nd, Sm, Eu, Tb, Dy, Ho, Er, Yb). Single X-ray crystallography confirms that the complexes exist as discrete dimeric pairs in the solid state. Proton NMR, diffusion-ordered spectroscopy, and luminescence solution studies suggest that the binuclear stoichiometry is retained in aqueous solution over a range of analytically useful concentrations. The phenolic chromophores effectively sensitize the visible and near-infrared lanthanide-centered emission in the terbium, neodymium, and ytterbium derivatives, giving rise to particularly long-lived green and near-infrared emission. The terbium complex displays a high quantum yield of around 50% in aqueous solution with a low detection limit of 1 x 10(-12) M, rendering this compound a potential candidate for time-resolved applications.     

Tuning the Excited State of Photoactive Building Blocks for Metal‐Templated Self‐Assembly

The reaction of 2,2′:4,4′′:4′,4′′′‐quaterpyridyl (qtpy), with d⁶ ruthenium(II) (Ru^II), and rhenium(I) (Re^I) metal centers has been investigated. The pendant pyridyl groups on the products have also been methylated to produce a second series of complexes containing coordinated Meqtpy²⁺. The absorption spectra of the complexes are dominated by intraligand and charge‐transfer bands. The ruthenium(II) complexes display broad unstructured luminescence consistent with emission from a Ru(d)→diimine(π*) manifold in acetonitrile solutions. In aqueous solutions, their emissions are weaker and the lifetimes are shorter. This effect is particularly acute for complexes incorporating coordinated dipyridylpyrazine, dppz, ligands. Although the emission of the ruthenium(II) complexes containing Meqtpy²⁺ is generally shorter than their qtpy analogs, it is notable that solvent‐dependent effects are much less intense. The rhenium(I) complexes also display broad unstructured luminescence but, compared with the ruthenium(II) systems, they have a relatively short lifetime in acetonitrile. Electrochemical studies reveal that all of the Ru^II complexes display chemically reversible metal‐based oxidations. Re^I complexes only display irreversible metal‐based oxidations. In most cases, the reduction processes were not fully chemically reversible. The electrochemical and optical studies reveal that the nature of the lowest excited state of these complexes—particularly, the systems incorporating dppz—is highly dependent on the nature of the coordinated ligands. Calculations indicate that, although the excited state of most of the complexes is centered on the qtpy or Meqtpy²⁺ ligands, the excited state of the complexes containing dppz ligands is switched away from the dppz by qtpy methylation. A crystallographic study on one of the dicationic ruthenium(II) structures reveals that it forms an inclusion complex with benzene.     

Crystal structure and luminescence property of ternary terbium p-aminobenzoic acid complexes with different second ligands

Ternary terbium complexes with p-aminobenzoic acid (HL), [TbL₃(DMSO)(H₂O)]₂ (1), [TbL₃(DMF)(H₂O)]₂ (2) and [TbL₃(Bpy)(H₂O)]₂·2H₂O (3) (DMSO=dimethyl sulfoxide, DMF=N, N- dimethylformamide, Bpy=2, 2′- bipyridyl) have been synthesized, and their crystal structures determined. The luminescence properties of these complexes, including both the emission quantum yield and the fluorescence lifetime, have been investigated. The effect of a second ligand on the crystal structure and luminescence property of the ternary terbium p-aminobenzoic acid complexes, and the relationship between luminescence properties and crystal structure, including coordination mode of the L⁻ ligand and the characteristics of a second ligand, are discussed.     

Use of microwave technology for the synthesis of organotitanium(IV) and organozirconium(IV) complexes with HPOH,HO<Superscript>∩</Superscript>N<Superscript>∩</Superscript>OH and HO<Superscript>∩</Superscript>N<Superscript>∩</Superscript>SH type of ligands

Synthesis and characterization of titanium(IV) and zirconium(IV) complexes of the types Cp₂M(Cl)(HPO), Cp₂M(HPO)₂, Cp₂M(O^∩N^∩O) and Cp₂M(O^∩N^∩S) (where M represents titanium or zirconium and HPO, O^∩N^∩O and O^∩N^∩S represent the donor sets of the ligands) have been reported. These new derivatives have been prepared by the reactions of titanocene dichloride or zirconocene dichloride with 2-hydroxy-N-phenyl benzamide(HPOH), 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazine-carboxamide (HO^∩N^∩OH) and 2-hydroxy-N-phenyl benzamide benzothiazoline (HO^∩N^∩SH) in different molar ratios. The ligands and their complexes have been characterized by the elemental analyses, conductance measurement, molecular weight determinations and spectral studies. On the basis of electronic, I.r., ¹H.-n.m.r. and ¹³C.-n.m.r. spectral studies, trigonal bipyramidal and octahedral geometries have been proposed for the resulting complexes. All the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found positive in this respect.     

From a Tb<Superscript>3+</Superscript> chelated compound to a hybrid material: selective emission responses to anions

A novel terbium 2-hydroxymethyl-benzoimidazole-6-carboxylic acid complex has been designed and unique emission changes to fluoride anions in comparison with HSO₄⁻, AcO⁻, Cl⁻, Br⁻, and I⁻ were observed. Then, the complex was encapsulated into an inorganic matrix. The novel hybrid material, with strong green emission was successfully synthesized as an anions receptor in water. More importantly, this hybrid material not only gave luminescence response to F⁻, but also to HSO₄⁻. Spectroscopic studies demonstrated that the recognition process for fluoride ions can be mainly ascribed to its hydrogen bonding interactions with hydrogen bond donor units (NH and OH). In case of hydrogen sulfate, the sensing effects can be probably attributed to its acidity instead of hydrogen bonding interactions.     

反应型三元铽配合物的合成及发光性能研究

以邻菲咯啉为第一配体，顺丁烯二酸酐、丙烯腈、十一烯酸、油酸、亚油酸为活性第二配体，合成了5种新的反应型三元铽配合物。通过元素分析，EDTA配位滴定分析，红外、紫外、荧光光谱分析，对标题配合物的组成、结构进行了表征，并研究了它们的发光性能。结果表明，五种新的反应型三元配合物与相应的二元配合物相比发光强度大大提高，且配合物中引入了能与其它单体共聚的活性第二配体，为合成具有优异发光性能的键合型稀土高分子功能材料提供了一条新的途径。     

Thermodynamics of Complex Formation of Ce<Superscript>3+</Superscript> and La<Superscript>3+</Superscript> Ions with Glycylglycine in Aqueous Solution

Enthalpy of the complex formation between diglycine (HL^±) and Ce³⁺ or La³⁺ at 308.15 K and ionic strength of 0.5 mol/L (KNO₃) has been determined by means of calorimetry. Thermodynamic parameters of the diglycine complexes formation with Ce³⁺ and La³⁺ at different metal to ligand molar ratios have been determined.     

New luminescent terbium complex for the determination of DNA

New terbium complexes of derivatives of 2-oxo-4-hydroxy-quinoline-3-carboxylic acid are reported, which are highly luminescent, water soluble and do not require luminescence enhancers. The triplet-state energy levels of the ligands, the relative quantum yields (QYs) and the excitation maxima of the respective terbium chelates were determined. The large luminescence enhancement of one of these complexes by nucleic acids was investigated and a mechanism of its interaction with DNA is proposed. The optimal conditions for determination of DNA are equal concentrations of Tb(3+) and ligand R(1) (C = 1 x 10(-6) M), pH 9.0. Under optimal conditions the luminescence intensity (RI) is proportional to the concentration of fish sperm DNA (fsDNA) or calf thymus DNA (ctDNA), respectively, within the range of 0.05-1.5 microg ml(-1). The detection limits were 10 ng ml(-1) for fsDNA and 12 ng ml(-1) for ctDNA.     

Luminescence Properties of Eu3+ Complexes of Tripode and Tetrapode Ligands Containing 2,2′-Bipyridine Units

The Eu³⁺ complexes of the tripode and tetrapode ligands 1 and 2 , respectively, containing 2,2′-bipyridine coordinating units have been prepared. The UV absorption and luminescence spectra, lifetimes, and quantum yields have been measured under a variety of experimental conditions. The contributions of different paths to the decay of the luminescent excited state are evaluated, and the structures of the complexes are discussed on the basis of spectroscopic and photophysical data.     

Complex compounds of terbium(III) with some nonsteroidal anti-inflammatory drugs and their analytical applications

Luminescence properties of the complexes of terbium(III) with nonsteroidal anti-inflammatory drugs (ibuprofen and orthofen) were studied. It was demonstrated that in the presence of organic bases (2,2’-dipyridyl and 1,10-phenanthroline) mixed-ligand complexes are formed and the luminescence intensity of terbium(III) increases by a factor of up to 250. The optimum complexation conditions were determined. It was proposed to use these complexes as analytical forms for the luminescence determination of nonsteroidal anti-inflammatory drugs (ibuprofen and orthofen) in pharmaceutical dosage forms. The detection limits are 2 and 0.05 μg/mL, respectively.