Investigation of WO4 2− - 3-Hydroxyflavone Complex in Water - Ethanolic Solution

By the application of the spectrophotometric methods the composition of the complex and by the pH-metric method the reaction of complex formation in 70% ethanol, were determined. It was found that a complex WO₃(C₁₅H₉O₃)₂ ^2- whose concentration stability constant β₂ ranged from 16.45 at pH 4.0 to 11.47 at pH 7.0, was formed. Conditions were investigated for the spectrophotometric determination of 3-hydroxyflavone by means of the reaction of complex formation. It was established that in 50% ethanol 3-hydroxyflavone can be determined with great accuracy in quantities from 0.05 to 0.30 mg/ml. All investigations were carried out at room temperature (20°C) and constant values of pH and ionic strength.     

Structural Investigation and Photoluminescent Properties of Gadolinium(III), Europium(III) and Terbium(III) 3-Mercaptopropionate Complexes

This work reports on the synthesis, crystallographic determination and spectroscopic characterization of gadolinium(III), terbium(III) and europium(III) 3-mercaptopropionate complexes, aqua-tris(3-mercaptopropionate)lanthanide(III) - [Ln(mpa)₃(H₂O)]. The Judd-Ofelt intensity parameters were experimentally determined from emission spectrum of the [Eu(mpa)₃(H₂O)]complex and they were also calculated from crystallographic data. The complexes are coordination polymers, where the units of each complex are linked together by carboxylate groups leading to an unidimensional and parallel chains that by chemical interactions form a tridimensional framework. The emission spectrum profile of the [Eu(mpa)₃(H₂O)] complex is discussed based on point symmetry of the europium(III) ion, that explains the bands splitting observed in its emission spectrum. Photoluminescent analysis of the [Gd(mpa)₃(H₂O)] complex show no efficient ligand excitation but an intense charge transfer band. The excitation spectra of the [Eu(mpa)₃(H₂O)] and [Tb(mpa)₃(H₂O)] complexes do not show evidence of energy transfer from the ligand to the excited levels of these trivalent ions. Therefore the emission bands are originated only by direct f-f intraconfigurational excitation of the lantanide(III) ions.     

Uptake of Europium(III) from Water using Magnetite Nanoparticles

It is demonstrated that colloidal magnetite nanoparticles can be used as nanosorbents for lanthanide ions dissolved in water. In particular, a series of experiments are performed for the removal of Eu(III) in distinct analytical conditions and by applying an external magnet to collect the sorbents previously dispersed in water samples. Furthermore, strategies for surface chemistry functionalization are also investigated, aiming to investigate the effect of this parameter on the removal capacity of the Fe₃O₄ nanoparticles. The supernatant solutions are monitored for the remaining amount of Eu(III) by fluorescence emission measurements in the presence of 2,6‐pyridinedicarboxylic acid as a sensitizer. The results demonstrate that neat Fe₃O₄ nanoparticles are capable of capturing lanthanide ions (III) from aqueous solutions (pH 7), without need of surface modification, and for subsequent removal by magnetic separation. During the removal, efficiency is increased after modifying the particles' surfaces with silica and 3‐aminopropyltrimethoxysilane; in alkaline medium (pH 10), there is complete removal regardless the type of nanosorbent used. This has been explained by the formation of insoluble Eu(III) species that adsorb strongly to the nanosorbents surfaces allowing their subsequent magnetic separation.     

Investigation of the Interaction Between Rutin and Trypsin in Solution by Multi-Spectroscopic Method

ABSTRACT

The interactions between rutin and trypsin were investigated by UV-Vis absorption, CD, fluorescence, resonance light-scattering spectra, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. Rutin effectively quenched the intrinsic fluorescence of trypsin via static quenching. The enthalpy change and entropy change were estimated to be ?8.23 kJ·mol^?1 and 53.66 J·mol^?1·K^?1 according to the van't Hoff equation. The process of binding rutin to trypsin was a spontaneous molecular interaction procedure. This result indicates that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The conformation of trypsin was discussed by CD, synchronous, and three-dimensional fluorescence techniques.     

Spectral-Luminescent Properties of Mixed-Ligand Europium(III) Complexes with p-Methylbenzoic Acid

Optics and Spectroscopy - The spectral-luminescent properties of europium(III) complexes with p-methylbenzoic acid and nitrogen- and phosphorus-containing neutral ligands of compositions...     

A Study on Some Europium(III) Supramolecules by Electrospray Mass Spectrometry

Electrospray mass spectrometry (ESMS) of a series of europium(III) supramolecules derived from tris(2-aminoethyl)amine (tren) and 2,6-diformyl-4-R-phenol (R = F, Cl, t-Butyl) is described. the peaks were assigned by both m / Z values and the isotope distributions. the ESMS are largely affected by the nature of the cryptates.     

Simultaneous Spectrophotometric Determination of Iron(II) and Iron(III) in Mixtures Using Di-2-pyridyl Ketone Benzoylhydrazone

A method for simultaneous spectrophotometric determination of total iron, iron(II) and iron(III) in mixtures containing other metal ions has been described. The method is based on the complexation of iron with di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution. Iron(II) complex with DPKBH exhibits two absorption maxima at 360 and 650 nm. meanwhile iron(II1) complex with DPKBH exhibits only one maximum at 360nm. Iron(II) and iron(III) complexes with DPKBH have similar behaviour at 360nm. Iron forms 1:2 complexes with the reagent. Beer's laws are obeyed over the ranges 0.1–2 μgml-1 and 0.4–5 μgrn1-l for iron(II) complexes at 360 and 650nm respectively. Iron(III) showed results similar to those obtained for iron(II) at 360nm. The effect of pH, effect of excess reagent. the stability of complexes. and the tolerance limit of many metal ions have been reported. The method is applied to the determination of total iron, iron(I1). and iron(II1) in synthetic solutions.     

Spectroscopic Determination of Heparin Sodium Using Europium (III) as a Probe Ion

Abstract

A sensitive, rapid, accurate and precise procedure for the microdetermination of heparin sodium in bulk, in injection and in blood serum. The procedure was built around the fact that heparin possesses many active binding sites; carboxylic, hydroxylic, amino and sulphonated groups, which are strongly bound to Eu³⁺ ions. Such binding enhances the europium emission at 616 nm which is a forbidden transition. The emission of europium at 592 nm comes from a non hypersensitive transition and is not affected by the ligand which is bound to europium ions. The intensity ratio R, defined as I₅₉₂/I₆₁₆ was used to determine the amount of free and bound europium ions. There is a linear relationship between bound europium ions and heparin sodium within the concentration range 1–12 ug. mL^?1 (0.07–0.84 USP. IN). Reaction conditions were studied and percentage recoveries was 99.77 ± 1.68. The relative stability of the complex was 1.2E⁵ and the correlation coefficient was 0.99923. Heparin was isolated from serum using ECTEOLA-cellulose and Sephadex G25 columns. The method shows good agreement with an anilinonaphthalene-1-sulfonate (ANS) and protamine fluorometric method.     

Enhancement of Europium Emission Band of Europium Tetracycline Complex in the Presence of Cholesterol

We report here the observation, for the first time, of the enhancement of Europium-Tetracycline complex emission in cholesterol solutions. This enhancement was initially observed with the addition of the enzyme cholesterol oxidase, which produces H₂O₂, the agent driver of the Europium tetracycline complex, to the solution. However, it was found that the enzyme is not needed to enhance the luminescence. A calibration curve was determined, resulting in a simple method to measure the cholesterol quantity in a solution. This method shows that the complex can be used as a sensor to determine cholesterol in biological systems.     

Y3+对水溶液聚合结构中Eu3+的荧光增强作用

合成了两种双功能的配体2,2＇,6,6＇-四羧基-4,4＇-联吡啶(BDPA)和双(2,6-二羧基-4-吡啶基)硫醚(SDPA).观察到Y3+能明显提高水溶液聚合结构中Eu3+的荧光强度.荧光增强机制表明,Eu3+、Y3+和配体所构成的水溶液聚合结构,有利于使Y3+配合物中的配体所吸收的能量有效地转移给Eu3+.     

Sensitization of Luminescence of Europium Compounds on Solid Matrices by Terbium (III) Ions

The conditions of sensitization of the luminescence of Eu(III) by Tb(III) ions in complexes with inorganic (Na₂WO₄) and organic (nalidixic acid) ligands in sorbates on solid matrices (zeolite CaX and crystalline zirconium phosphate (ZrP)) and in coprecipitation with CaWO₄ have been investigated. It has been established that the maximum sensitization of the europium luminescence is attained in the case where Eu and Tb are present in a 1:0.5 ratio. In this case, the integral intensity of luminescence of Eu(III) (the band with _max = 612 nm) in the sorbate of its complex with nalidixic acid on ZrP accounts for more than 60% of the luminescence intensity of the industrial photoluminophor Y₂O₃:Eu (FL-612) possessing red luminescence, and the intensity of Tb(III) luminescence (the band with _max = 545 nm) accounts for about 40% of the luminescence intensity of the photoluminophor Gd₂O₂S:Tb possessing green luminescence.     

Blue LED Excitable Temperature Sensors Based on a New Europium(III) Chelate

A new europium(III) chelate is synthesized and characterized. The wavelength of sensitization of Eu³⁺ luminescence is shifted further into visible so that efficient excitation with 425, 435 and 450-nm LEDs becomes possible. Photophysical properties and temperature dependence of luminescence are investigated in toluene solution and various polymer matrixes. The sensor materials are also characterized in terms of cross-sensitivity to oxygen and photostability. The sensor material based on the europium complex immobilized into poly(vinylidene chloride-co-acrylonitrile) shows negligible cross-sensitivity to oxygen and is particularly attractive for applications at physiological conditions. Other materials can be applied for sensing and imaging purposes at room temperatures. The new materials can also be used for compensating optical (oxygen, CO₂ etc.) sensors for temperature effects.     

Luminescent Properties of Europium(III) Compounds with Quinolinic Acid and Phosphorus-Containing Neutral Ligands

Optics and Spectroscopy - Luminescent mixed-ligand europium(III) complexes with quinolinic acid and phosphorus-containing neutral ligands with a dimeric structure of the composition Eu2(QA)3 ·...     

Break-Through Investigation on Uranium Isotope Separation in the System Uranyl Ion Solution Ti(III)-Cationic Resin

A break-through experiment on separation of uranium isotopes was carried out by use of a cation-exchange resin in Ti(III) form. By analyzing the experimental results the apparent equilibrium constants of the order K = 1·00021–1·00034 were determined.

The maximum value on the experimental curies of the isotopic ratio versus effluent volume was interpreted by considering two antagonistic isotope effects: one relatively large given by an exchange reaction between U(IV) in resin and U(VI) in solution and another smaller given by the reduction reaction of U(VI) with Ti(III). The difference of the equilibrium constants of the these two isotope effects as a function of temperature was used for the determination of the apparent thermodynamic values of the resultant process, determined experimentally: ΔH⁰ = 0.8542 cal mol^?1 and ΔS⁰ = 3.33×10^?3cal°K^?1.     

Proton Magnetic Resonance Studies of Al(III) and Ga(III) Hydration Numbers in Aqueous Solution

Schweitzer and Stephens have recently suggested that the hydration numbers of Al³⁺ and Ga³⁺ and Ga³⁺ in aqueous solutions containing a considerable excess of chloride ion are probably less than six. Hydration numbers as low as 4.64 (in 1.44 M AlCl₃+ 2.15 M CaCl₂) or 4.61 (in 0.645 M GaCl₃+ 3.32 M CaCl₂) were obtained.¹ That Ga³⁺ forms chloro-complexes under these conditions is well known though interaction between Al³⁺ and chloride is considered unlikely in aqueous solution.^2–4     

钇与偶氮氯膦MK多配位络合物溶液光谱性质的研究

在ＰＨ３．２９溶液中,钇（Ⅲ）与偶氮氯膦ＭＫ（ＣＰＡＭＫ）发生灵敏配位反应,本文应用β－修正分析理论研究此研究合物溶液性质的测定,包括配位比,逐级摩尔吸收系数、络合物稳定常数等。     

Investigation of the Europium Emission Spectra of the Europium-Oxytetracycline Complex in the Presence of Human Low-Density Lipoproteins

Low-Density Lipoprotein (LDL), often known as “bad cholesterol” is one of the responsible to increase the risk of coronary arterial diseases. For this reason, the cholesterol present in the LDL particle has become one of the main parameters to be quantified in routine clinical diagnosis. A number of tools are available to assess LDL particles and estimate the cholesterol concentration in the blood. The most common methods to quantify the LDL in the plasma are the density gradient ultracentrifugation and nuclear magnetic resonance (NMR). However, these techniques require special equipments and can take a long time to provide the results. In this paper, we report on the increase of the Europium emission in Europium-oxytetracycline complex aqueous solutions in the presence of LDL. This increase is proportional to the LDL concentration in the solution. This phenomenum can be used to develop a method to quantify the number of LDL particles in a sample. A comparison between the performances of the oxytetracycline and the tetracycline in the complexes is also made.     

Luminescent Chemosensor Properties of Eu(III) Complex Compounds

Optics and Spectroscopy - Luminescent chemosensor properties of Eu(III) carboxylate dibenzoylmethanates are observed. It is shown that the interaction of Eu(III) complexes with ammonia or...     

Spectral-Luminescent Properties of Mixed-Ligand Europium(III) Complexes with O-Methoxybenzoic Acid and Phosphorus-Containing Neutral Ligands

Optics and Spectroscopy - The spectral-luminescent properties of europium(III) complexes with o-methoxybenzoic acid and phosphorus-containing neutral ligands with an island structure and the...     

Spectrophotometric Determination of Sm(III) Content in Hydrochloric Acid Solution

On the basis of the electronic absorption spectra of Sm³⁺ ions in aqueous solutions of hydrochloric and perchloric acids (1M) calibration plots of samarium content against the optical density of the solutions have been constructed for frequencies 47,800, 31,460, 29,140, 27,760, 26,740, 24,940, 24,020, 21,580, and 20,900 cm^–1 corresponding to the optical density maxima. The results of the calculation of errors in determining the metal concentration are presented. It has been shown that for hydrochloric acid solutions of samarium correct determination of its content is possible at frequencies 24,940, 21,580, and 20,900 cm^–1 in the concentration ranges 1.0–3.5, 2.5–5.0, and 0.08–5.00%, respectively. For perchloric acid solutions of samarium, correct determination of its content is possible at the 24,940 cm^–1 frequency in the concentration range from 1.0 to 3.5%.