Europium-sensitized luminescence determination of oxytetracycline in catfish muscle

An europium-sensitized time-resolved luminescence (TRL) method was developed to determine oxytetracycline (OTC) in cultivated catfish muscle. Extraction of OTC from fish muscle was performed with pH 4.0 ethylenediaminetetraacetic acid (EDTA)-McIlvaine buffer and clean up with hydrophilic-lipophilic balanced copolymer solid phase extraction (SPE) cartridges. The eluate was used without further concentration for TRL measurement in pH 9.0 micellar tris(hydroxylmethyl)aminomethane (TRIS) buffer. Cetyltrimethylammonium chloride (CTACl) was used as surfactant and EDTA as a co-ligand. The excitation and emission wavelengths were set at 388 and 615 nm, respectively. The linear dynamic range was 0-1000 ng g⁻¹ (R²=0.9995). The recovery was 92-112% in the fortification range of 50-200 ng g⁻¹ and the limits of detection (LOD) ranged from 3 to 7 ng g⁻¹. Incurred catfish samples were used to demonstrate the performance of the method around 100 ng g⁻¹, the European Union maximum residue level.     

Synthesis, structure and luminescence property of the ternary and quaternary europium complexes with furoic acid

A ternany europium complex with furoic acid (α-FURA) and 1,10-phenanthroline(phen), [Eu(α-FURA)₃phen]H₂O(I) and a quaternary europium furoate complex with 1,10-phenanthroline and nitrate, Eu(α-FURA)₂NO₃phen(II) were synthesized and characterized by X-ray diffraction. The two europium ions in each of the complexes (I) and (II) are held together by four carboxylato groups with the two modes, namely bidentate bridging and tridentate bridging, and each europium ion is further bonded to two nitrogen atoms from 1,10-phenanthroline and one chelated bidentate furoate group for the complex (I) and one chelated nitrato group for the complex (II), making a coordination number of 9. Luminescence spectra observed at 77 K show that the europium ion site in the crystals of the complexes (I) and (II) has low symmetry and lifetimes of the solid complexes (I) and (II) are 1.13 and 1.20 ms, respectively.     

Synthesis,crystal structure,and luminescence of a quaternary binuclear europium complex [Eu2(phth)2(Hphth)2(phen)2(H2O)4]

A quaternary binuclear europium complex [Eu₂(phth)₂(Hphth)₂(phen)₂(H₂O)₄] (H₂phth?=?phthalic acid, phen?=?1,10-phenanthroline) has been synthesized. The structure was determined by X-ray crystallography which reveals that it is binuclear with each europium nine-coordinate. Intermolecular hydrogen bonds link the complex units to form a 3D supermolecular network. Its properties have been studied by means of luminescence spectrum and thermal analysis. Fluorescence spectra show that the complex exhibits strong red emission.     

(Tetracycline)europium(III) Complex as Luminescent Probe for Hydrogen Peroxide Detection

Luminescence spectra of aqueous solutions containing a fixed concentration of tetracycline (TC) and increasing concentrations of Eu³⁺ were recorded both in the absence and presence of hydrogen peroxide (H₂O₂). In H₂O₂‐free solutions in which the Eu/TC molar ratio was varied from 1 : 1 to 8 : 1, the ⁵D₀→⁷F₀ transition consisted of only one peak at 580 nm. In the presence of H₂O₂, an extra peak appeared in the spectrum at 578 nm when the Eu/TC molar ratios were above 2.5. A detailed analysis of this spectral region revealed that at lower Eu/TC molar ratios (up to 2 : 1), the ⁵D₀→⁷F₀ transition experienced a slight blue shift. This indicates that at low Eu/TC molar ratios, the presence of H₂O₂ leads to two different environments of the trivalent europium ions, which most likely form bridged peroxide complexes with hydrogen peroxide (μ‐H₂O₂ ligand). Luminescence spectra measured in the presence of molybdate ions, which catalytically decompose H₂O₂, led to the disappearance of the extra europium(III) site that was formed in the presence of H₂O₂. The intensity of the hypersensitive ⁵D₀→⁷F₂ transition did not linearly depend on the H₂O₂/TC molar ratio. For H₂O₂/TC ratios up to 10, a sharp linear increase of the peak intensity was observed, but with further increase of the H₂O₂ concentration, the intensity remained nearly constant. For H₂O₂/TC ratios above 100, the intensity of this transition even started to decrease, which limits the use of the (tetracycline)europium(III) system to quantify hydrogen peroxide in solution.     

Synthesis,crystal structure and luminescence of three europium complexes with 2-iodobenzoic acid

Three new complexes, [Eu(2-IBA)₃?·?H₂O] _n (1), [Eu(2-IBA)₃?·?2,2′-bpy]₂ (2), and [Eu(2-IBA)₃?·phen]₂ (3) (2-IBA?=?2-iodobenzoato; 2,2′-bpy?=?2,2’-bipyridine; phen?=?1,10-phenanthroline) were synthesized, and their crystal structures determined by X-ray diffraction. In complex 1, Eu³⁺ ions are linked through carboxylate groups via bridging – chelating – bridging coordination modes to form a one-dimensional polymeric chain. The carboxylate groups are tetradentate-bridged. Complex 2 is binuclear with an inversion center, in which europium is nine-coordinated with seven oxygen atoms from five 2-IBA ligands and two nitrogen atoms from one 2,2′-bpy molecule in a distorted monocapped square antiprism. The crystal structure of 3 is similar to that of 2. These complexes emit red light luminescence. The ⁵ D ₀?→?⁷ F _j (j?=?1–4) transition emission of Eu³⁺ ion has been observed.     

Optical properties of a tetradentate bis(beta-diketonate) europium(III) complex

Eu₂(BPOPB)₃H₂O, an europium complex chelated with bis(β-diketone), was synthesized. Its properties have been investigated by absorption spectrum, emission spectrum and luminescence lifetime measurement. The complex displays strong red luminescence upon irradiation at the ligand band around 355 nm, which indicates that the bis-β-diketonate ligand BPOPB is an efficient sensitizer. The Judd–Ofelt parameters obtained from the emission spectrum of Eu₂(BPOPB)₃H₂O have been used to calculate the total spontaneous emission probabilities (A), the radiative lifetime (τ_rad), the fluorescence branching ratio (β) and the stimulated emission cross-sections (σ). The luminescence lifetimes are determined to be 402 and 169 μs for Eu₂(BPOPB)₃H₂O and Eu(DBM)₃(H₂O)₂, respectively. The relationship between the structures of rare-earth complexes and luminescence lifetimes was analyzed. The radiative properties reveal that Eu₂(BPOPB)₃H₂O is potential to be an efficient luminescent material.     

Energy transfer between 1,3-dimethylxanthine and europium(III) in aqueous solution

Luminescence of 1,3-dimethylxanthine in solution is impaired owing to collisional deactivation by solvent molecules and matrix interferences. Energy absorbed by 1,3-dimethylxanthine has been transferred to trivalent europium which emits narrow-band radiation in a region distant from background interferences. The enhanced luminescence of trivalent europium was utilized for the determination of 1,3-dimethylxanthine in buffered aqueous solution. An analytically useful range from 1.1 × 10^?5?5.0 × 10^?4 M and a detection limit of 1.1 × 10^?5 M were obtained. The methodology for the analytical procedure was determined.     

Determination of adenosine disodium triphosphate (ATP) using oxytetracycline-Eu3+ as a fluorescence probe by spectrofluorimetry

A new spectrofluorimetric method was developed for determination of adenosine disodium triphosphate (ATP). We studied the interactions between oxytetracycline (OTC)-Eu3+ complex and adenosine disodium triphosphate (ATP) by using UV-vis absorption and fluorescence spectra. Using oxytetracycline (OTC)-Eu3+ as a fluorescence probe, under the optimum conditions, ATP can remarkably enhance the fluorescence intensity of the OTC-Eu3+ complex at lambda = 612 nm and the enhanced fluorescence intensity of Eu3+ ion is in proportion to the concentration of ATP. Optimum conditions for the determination of ATP were also investigated. The linear ranges for ATP are 8.00 x 10(-8)-1.50 x 10(-6) mol L(-1) with detection limits of 2.67 x 10(-9) mol L(-1). This method is simple, practical and relatively free interference from coexisting substances and can be successfully applied to determination of ATP in samples. The mechanism of fluorescence enhancement between oxytetracycline (OTC)-Eu3+ complex and ATP was also studied.     

Synthesis and photovoltaic properties of new europium complex Eu（DBM）3（CPyBM）

A new europium（Ⅲ） complex, tris（dibertzoylmethanate）{ 1-[9-hexyl-9-carbazole]-2-（2-pyridyl）-bertzimidazole}europium（Ⅲ） [Eu（DBM）a（CPyBM）] was synthesized and used as an electron-acceptor and electron-transport layer in organic photovoltaic （PV） device. Power conversion efficiency achieved from the device was 1.04% under illumination with 365 nm UV light at 1.6 mW/cm^2. Compared with the previous reported devices based on Eu（Ⅲ） complexes, the PV performances were improved. The working mechanism of the organic PV device was discussed.     

Highly sensitive and selective spectrofluorimetric determination of metoclopramide hydrochloride in pharmaceutical tablets and serum samples using Eu ion doped in sol-gel matrix

A simple, sensitive and selective spectrofluorimetric method for the determination of Metoclopramide hydrochloride (MCP) is developed. The MCP can remarkably enhances the luminescence intensity of the Eu³⁺ ion doped in sol-gel matrix at λ_ex = 380 nm in DMSO at pH 8.7. The intensity of the emission band of Eu³⁺ ion doped in sol-gel matrix increases due to energy transfer from MCP to Eu³⁺ in the excited state. The enhancement of the emission band of Eu³⁺ ion doped in sol-gel matrix at 617 nm was found to be directly proportional to the concentration of MCP with a dynamic range of 5 × 10⁻⁹ − 1.0 × 10⁻⁶ mol L⁻¹ and detection limit of 2.2 × 10⁻¹¹ mol L⁻¹.     

Influence ofpH and concentration of complexing agents on fluorescence of europium (III) ethylenediaminetetraacetic acid and europium (III) nitrilotriacetic acid complexes in aqueous solutions

The fluorescence of aqueous solutions of Eu(III) complexes withEDTA andNTA has been investigated. Intensities of the fluorescence bands have been measured as a function of complexone concentrations in the solutions and thepH. The results are interpreted in terms of the different forms of Eu(III) complexes and their relative stabilities.

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Einfluß vonpH und Konzentration der Komplexbildner auf die Fluoreszenz der Komplexe des Europium (III) mit Ethylendiamintetraessigsäure und Nitrilotriessigsäure in wäßrigen Lösungen

Zusammenfassung Die Fluoreszenz von wäßrigen Lösungen der Komplexe des Europium(III) mit Ethylendiamintetraessigsäure und Nitrilotriessigsäure wurde untersucht. Die Intensitäten der Fluoreszenzbanden in Abhängigkeit vonpH und Konzentration der Komplexbildner wurden auf der Basis vorkommender Komplexgeometrien und deren Stabilitäten interpretiert.

     

Highly efficient and selective turn-off quenching of ligand-sensitized luminescence from europium imidazo[4,5-f]-1,10-phenanthroline complex by fluoride ion

A smart fluoride sensitive luminescence probe based on 1:2 complex of europium(III) with 2-(2-hydroxyphenyl)imidazo[4,5-f]-1,10-phenanthroline was prepared. The emission of europium ions via photosensitization of the ligand was completely quenched by addition of 2 equiv. of fluoride ions in DMSO. Spectroscopic analyses proved that the imidazolyl NH of the ligand was hydrogen-bonded with additive fluoride to form the 1:1 complex, leading to suppression of the photosensitization.     

Crystal structure and luminescence of europium(III) acrylate

The atomic structure of europium acrylate crystals [Eu₂(Acr)₅OH·3H₂O]·2(0.5H₂O) was studied by X-ray analysis (a = 24.360(3) Å, b = 18.466(2) Å, c = 8.5818(9) Å, β = 96.087(2)°, space group C2/c, Z = 6, ρ_calc = 2.036 g/cm³). The crystal structure involves chains of binuclear [Eu₂(C₃H₃O₂)₅OH·3H₂O] molecules, running infinitely in the [101] direction and having pairs of C₉H₉EuO₇H₂O molecules alternating with C₆H₆EuO₄OH·2H₂O molecules that link the pairs. The infinite chains are linked by hydrogen bonds and van der Waals interactions. The thermal behavior of luminescence of the europium(III) complex is discussed.     

Application of europium(III) chelates-bonded silica nanoparticle in time-resolved immunofluorometric detection assay for human thyroid stimulating hormone

Eu(III) chelate-bonded silica nanoparticle was used as a fluorescent label to develop a highly sensitive time-resolved immunofluorometric assay (TrIFA) for human thyroid stimulating hormone (hTSH). The limit of detection of the assay calculated according to the 2SD method was 0.0007 mIU L⁻¹ and became 0.003 mIU L⁻¹ when serum-based matrix was used for calibrators, indicating that this TrIFA is comparable with the most sensitive assays. The linear range was from 0.005 to 100 mIU L⁻¹ of hTSH with coefficient of variation between 1.9% and 8.3%. The correlation study using 204 blood spot samples from newborns showed that the results from this new method were coincident with that of the commercial dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA) system, with a correlation coefficient of 0.938. The fluorescent nanoparticle label allows directly reading the fluorescent signal, omitting the signal development step required for the DELFIA system, and the whole procedure of this assay is fulfilled within 2 h. Thus, we developed a novel, sensitive, quantitative and simple nanoparticle label-based TrIFA assay, suitable for routine application in hTSH screening of neonatal hypothyroidism.     

Luminescence Investigations on Eu(III) Thenoyltrifluoroacetonate Complexes with Amide Ligands

The influence of amide ligands on the photoluminescent behavior of tris(thenoyltrifluoroacetonate)- europium(III) in the solid state is reported. Elemental analysis showed that these compounds have the following formulas [Eu(TTA)₃·(ANL)₂] and [Eu(TTA)₃·PZA], where ANL = acetanilide and PZA = pyrazinamide. The photoluminescence spectra of the complexes recorded in the range 420-720 nm at 77 K show narrow bands arising from the ⁵D₀ → ⁷F _J transitions (where J = 0-4), under excitation at 394 nm. Based on the emission spectra and luminescence decay curves the intensity parameters (Ω_λ), lifetime (τ) and emission quantum efficiency (η) were determined. The Ω₂ values indicate that the Eu³⁺ion in these complexes is in a highly polarizable chemical environment. The higher value of η (60%) obtained for the complex with the ANL ligand, in comparison with the complex with the PZA ligand (30%), indicates a more efficient deactivation of the Eu³⁺ion in the [Eu(TTA)₃·PZA] complex.     

Luminescent sensing of organophosphates using europium(III) containing imprinted polymers prepared by RAFT polymerization

Molecularly imprinted polymers capable of sensing organophosphorous compounds by luminescence have been prepared by reversible addition fragmentation chain transfer (RAFT) polymerization. The polymer contained a dithiobenzoate substituted tris(β-diketonate) europium(III) complex which served as a polymerization substrate and as a luminescent binding site for pinacolyl methylphosphonate (PMP), the hydrolysis product of the nerve agent Soman. The resultant polymer allowed quantitation of PMP in the low ppb range with minimal interference from similar compounds. Polymers were characterized by luminescence spectroscopy and scanning electron microscopy.     

Anti-Stokes luminescence of europium(III)-doped lanthanum oxychloride

The anti-Stokes luminescence from the ⁵D_1,2,3 levels of Eu³⁺-doped LaOCl was observed at 300 and 77 K under dye-laser excitation to the ⁵D₀ level. A two-photon absorption from the ⁷F₀ ground level to charge-transfer states via the ⁵D₀ level was concluded to be the mechanism involved. The absorption of the first photon through the forbidden ⁵D₀→⁷F₀ transition determines the upconversion efficiency. The two-photon absorption seems to occur as an intra-ion process without interionic energy transfer.     

Eu(BA)3phen的晶体结构和荧光光谱

标题配合物晶体属三斜晶系，Ｐ１空间群，晶胞参数ａ＝１０７９２（２）ｎｍ，ｂ＝１１８９６（２）ｎｍ，ｃ＝１２４４６ｎｍ，α＝１０５１２（３）°，β＝９３７６（３）°，γ＝１１３１９（３）°，Ｖ＝１３９２（１）ｎｍ－３，Ｚ＝２，Ｄｘ＝１６５９ｇ·ｃｍ－３。配合物晶体由双核分子组成，两个中心Ｅｕ３＋通过羧基桥联，它们的化学环境相同。Ｅｕ３＋的配位数为８，其配位多面体为一畸变的四方反棱柱体。在７７Ｋ配合物的荧光光谱说明配合物中仅存在一种Ｅｕ３＋格位。