Valence States and Luminescence Properties of Ytterbium Ions in Strontium Haloborates

The luminescence properties of ytterbium ions in strontium haloborates were studied under optical, X-ray and synchrotron excitation. The coexistence of Yb ions in two valence states (divalent and trivalent) was detected in the Sr₂B₅O₉X:Yb (X=Cl, Br) powder materials prepared in a slightly reducing (H₂/N₂) or an oxidizing atmosphere. Under optical excitation, the 5d→4f Yb²⁺ luminescence at 420 nm is observed. Even under X-ray excitation, an emission band with a maximum of about 340nm appears in the spectra. This broadband emission is attributed to charge transfer luminescence of Yb³⁺. The influence of the structural features of Sr₂B₅O₉X and some preparative conditions of the samples on the luminescent behavior of Yb are discussed.     

Study of the cyclotron production of <Superscript>172</Superscript>Lu: an excellent radiotracer

¹⁷²Lu due to its suitable (T _1/2 = 6.7 days) and high detection sensitivity, is used as a radiotracer in different fields. ¹⁷²Lu appears to be suitable as a long-lived rare-earth tracer for compound labelling and biodistribution studies. In the present study, excitation functions via ¹⁷²Yb(p,n)¹⁷²Lu, ^natYb(p,xn)¹⁷²Lu, ¹⁷²Yb(d,2n)¹⁷²Lu and ^natYb(d,xn)¹⁷²Lu reactions were calculated by ALICE/91, ALICE/ASH and TALYS-1.2 codes. Deposition of ^natYb₂O₃ on Cu substrate was carried out via sedimentation method for the production of ¹⁷²Lu. Cementation separation process and liquid–liquid extraction (LLX) of no-carrier-added (nca) radiolutetium from irradiated ytterbium(III)oxide target hydrochloric solution was described using Na(Hg) amalgam, α-hydroxyisobutyric acid (α-HIB) and di-(2-ethylhexyl)phosphoric acid (HDEHP).     

A scheme for the analysis of monazite and monazite concentrates

A scheme using ion-exchange methods is described for the analysis of monazites and monazite concentrates. The sample is opened up with concentrated sulphuric acid, and the resultant solution is applied to a column of Zeocarb 225 resin. After phosphate has been washed out, lead, aluminium, titanium, iron, uranium, calcium and magnesium are eluted with N hydrochloric acid and determined by specific, mainly spectrophotometric, methods. Rare earth elements are eluted with 3 N hydrochloric acid. Cerium is separated from the other rare earths by solvent extraction of its nitrate with methyl iso-butyl ketone; both groups are determined gravimetrically. Thorium is eluted from the ion-exchange resin with 3.6 N sulphuric acid and determined spectrophotometrically with thorin.The sulphuric acid-insoluble minerals are brought into solution by a double fusion method, and the determinations are carried out by a combination of ion-exchange and photometric procedures. Silica, phosphorus pentoxide, tin and chromium are determined by photometric methods, using separate portions of the sample.Lanthanum, yttrium and ytterbium are determined in a 1 M perchloric acid solution of the mixed rare earth oxides (less cerium) using flame photometry. Samarium, praseodymium and neodymium are determined by spectrophotometry.     

Yb(OTf)3-Catalyzed 1,3-dipolar cycloaddition of nitrone with alkene; Switch in diastereoselectivity by solvent and bidentate auxiliary

Yb(OTf)₃ (ytterbium trifluoromethanesulfonate)-catalyzed diastereoselective 1,3-dipolar cycloaddition of a nitrone with α,β-unsaturated carbonyl compounds was studied. While endo-cycloadduct was obtained from the reaction of C, N-diphenylnitrone with N-crotonoyl-oxazolidinone or N-crotonyl-2-pyrrolidinone in toluene, exo-adduct was predominant in acetonitrile. The enones carrying imidazolidinone or succinimide ring reacted with the nitrone to give the exo-adducts primarily in both solvents.     

Single-step radiochemical separations by column procedures in activation analysis

Some single-step column procedures are described for both individual and group activity separations. Besides the usual ion-exchange techniques, other methods such as reverse-phase chromatography, isotopic exchange and the use of resins converted into special forms were used. Fast and simple selective separations from 2N hydrochloric acid are reported for Mo(VI), Cu(II), Sb(V), and for AsO₄^3- + PO₄^3- from both 2 N hydrochloric acid and I N sulfuric acid; for Cu, Sb and As + P, the selectivity can be greatly increased by using a guard bed of resin in normal form. By combining the different techniques a single-step separation scheme for 6 elements (Mo, Au, Zn, As, Cu, Sb) in 2 N hydrochloric acid was developed; this allows high chemical recoveries, high cross-decontamination and very large decontamination from ²⁴Na to be reached, so that application for biological sample analysis can be envisaged. Simplified two-stage column separations for Au + Sb and Cu and Fe + Sb and Zn from concentrated hydrochloric acid (cationic and anionic resin beds coupled) are also reported.     

Effect of L-ascorbic acid on the bioretention of169Yb

Studies with L-ascorbic acid as biological complexing agent have been performed to investigate its influence on the uptake and retention of the radionuclide of ytterbium in animals. The experimental results indicate that the retention of¹⁶⁹Yb in the investigated organs of mice is affected when¹⁶⁹YbCl₃ is simultaneously administered to the animal with L-ascorbic acid. L-ascorbic acid has little or no effect on the¹⁶⁹Yb excretion when it is pre- or post-¹⁶⁹YbCl₃ injected.     

Novel Ytterbium(III) Selective Membrane Sensor Based on N‐(2‐Pyridyl)‐N′‐(2‐Methoxyphenyl)‐Thiourea as an Excellent Carrier and Its Application to Determination of Fluoride in Mouth Wash Preparation Samples

The construction, performance, and applications of a novel ytterbium(III) sensor based on N‐(2‐pyridyl)‐N′‐(2‐methoxyphenyl)‐thiourea (PMT), as an excellent carrier, in plasticized poly(vinyl chloride) PVC matrix, is described. The influences of membrane composition and pH on the potentiometric response of the sensor were investigated. The sensor exhibits a nice Nernstian response for Yb(III) ion over a wide concentration range of 4 decades of concentration (1.0×10^?6–1.0×10^?2 M), and a detection limit of 5.0×10^?7 M. The response time of the electrodes is between 8 and 10 s, depending on the concentration of ytterbium(III) ions. The proposed sensor can be used for about 8 weeks without any considerable divergence in potential. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. The best performance was observed for the membrane containing; 30% PVC, 59% o‐nitrophenyloctyl ether (NPOE) as solvent mediator, 7% PMT, and 4% sodium tetraphenyl borate (NaTPB). It was successfully applied as indicator electrodes in the potentiometric titration of Yb(III) with EDTA and for the determination of fluoride ion in two mouth wash formulations. The proposed La(III) sensor was found to work well under laboratory conditions. It was also used as an indicator electrode in titration of a 1.0×10^?4 M of Yb(III) with a standard EDTA solution (1.0×10^?2 M). It was also used for determination of Yb(III) ion in Xenotime .     

Lanthanide(III) nitrobenzenesulfonates and p-toluenesulfonate complexes of lanthanide(III), iron(III), and copper(II) as novel catalysts for the formation of calix[4]resorcinarene

Lanthanide(III) salts of p-toluenesulfonic acid [lanthanide(III) tosylates, Ln(TOS)₃] and nitrobenzenesulfonic acid [Ln(NBSA)₃], and p-toluenesulfonate complexes of iron(III) and copper(II) were prepared, characterized, and examined as catalysts for the synthesis of resorcinol-derived calix[4]resorcinarenes. The reaction of resorcinol with benzaldehyde yields two isomers, the all-cis isomer (rccc) and the cis-trans-trans isomer (rctt) with the relative isomer ratios depending on the reaction conditions. However, in the reaction of resorcinol with octanal only one isomer, the all-cis isomer, is formed in high yields with less than 0.1 mol % of Yb(TOS)₃. Examination of lanthanide(III) tosylates and lanthanide(III) nitrobenzenesulfonates revealed that ytterbium(III) 4-nitrobenzenesulfonate [ytterbium(III) nosylate, Yb(4-NBSA)₃] and ytterbium(III) 2,4-dinitrobenzenesulfonate [Yb(2,4-NBSA)₃] are the most active catalysts. The catalysts could be easily recovered and reused several times for resorcinarene formation without loss of efficiency. Surprisingly good results were also obtained with iron(III) and copper(II) p-toluenesulfonates. Besides optimizing the reaction conditions, new insights into the reaction mechanism were also obtained.     

Practical aspects of simultaneous determination of selenium and ytterbium by neutron activation analysis

An instrumental method for the simultaneous determination of selenium and ytterbium by thermal neutron activation analysis is described. Selenium and ytterbium were determined via the 400.7 keV photopeak of⁷⁵Se and the 177 keV photopeak of¹⁶⁹Yb. The accuracy of this instrumental method has been examined; as a result, it has been proved that this method is most exact and accurate when the gamma-ray counting is carried out after the decay of¹⁷⁵Yb.     

Thermo-induced structural transformation with synergistic optical and magnetic changes in ytterbium and erbium complexes

Dinuclear ytterbium and erbium based bifunction complexes Ln₂L₂(depma₂)Cl₂ (1-Ln, Ln = Yb and Er, H₂L = N¹,N³-bis(salicylideneimino)diethylenetriamine, depma₂ = dimerized 9-diethyl-phosphonomethylanthracene) are reported. They undergo thermo-induced consecutive phase transitions, first the dissociation of depma₂ ligand forming LnL(depma)Cl (2-Ln) and then the release of chloroethane forming LnL(epma) (3-Ln, epma = 9-ethylphosphonomethylanthrancene). The structural transformations are accompanied with synergetic switch of the luminescence in visible and NIR regions and also magnetic dynamics.     

Magnetic Investigations and 151Eu Mössbauer Spectroscopy of MYbSi4N7 with M = Sr,Ba, Eu

The isotypic nitridosilicates MYb[Si₄N₇] (M = Sr, Ba, Eu) were obtained by the reaction of the respective metals with Si(NH)₂ in a radiofrequency furnace below 1600 °C. On the basis of powder diffraction data of MYb[Si₄N₇] Rietveld refinements of the lattice constants were performed; these confirmed the previously published single‐crystal data. The compounds contain a condensed network of corner‐sharing [N(SiN₃)₄] units. The central nitrogen thus exhibits ammonium character. Magnetic susceptibility measurements of MYb[Si₄N₇] (M = Sr, Ba, Eu) show paramagnetic behavior with experimental magnetic moments of 3.03(2), (Sr), 2.73(2) (Ba), and 9.17(2) (Eu) μ_B per formula unit. In EuYbSi₄N₇ the europium and ytterbium atoms are in stable divalent and trivalent states, respectively. According to the non‐magnetic character of the alkaline earth cations, ytterbium has to be in an intermediate valence state Yb^III‐x in the strontium and barium compound. Consequently, either a partial exchange N^3—/O^2— resulting in compositions MYb^III‐x[Si₄N_7—xO_x] or an introduction of anion defects according to MYb^III‐x[Si₄N_7—x/3□_x/3] has to be assumed. The phase width 0 ≤ x ≤ 0.4 was estimated according to the magnetic measurements. ¹⁵¹Eu Mössbauer spectra of EuYb[Si₄N₇] at 78 K show a single signal at an isomer shift of δ = —12.83(3) mm s^—1 subject to quadrupole splitting of ΔE_Q = 5.7(8) mm s^—1, compatible with purely divalent europium.     

Separation of 90Y from 90Sr using sequential multiple column extraction chromatography

The distribution coefficient measurements on Y(III) and Sr(II) were performed using ditertiarybutyl dicyclohexano 18-crown-6 (Sr-selective resin) and N,N,N′,N′-tetraoctyldiglycolamide (Y-selective resin) in HNO₃, HCl and HClO₄ media. Separation factors (⁹⁰Y/⁹⁰Sr) based on distribution coefficient data suggested that perchloric acid is distinctly better medium as compared to nitric acid/hydrochloric acid. The mechanism of extraction changes with the nature and concentration of acid and is responsible for the high selectivity in perchloric acid medium. Sequential column studies were carried out on tracers (radioactive/stable) employing Sr-selective/Y-selective extraction chromatographic resins as stationary phases. The final elution of ⁹⁰Y was done in 0.01 M EDTA at pH 4.0 which can be used for clinical applications after radiochemical processing.     

Study on volatilization of ytterbium as 1-(2-pyridylazo)-2-naphthol chelate from electrothermal vaporizer for sample introduction in inductively coupled plasma atomic emission spectrometry

Based on the formation of a volatile 1-(2′-pyridylazo)-2-naphthol (PAN) chelate, a novel method was described for the determination of trace ytterbium by electrothermal vaporization (ETV)-inductively coupled plasma atomic emission spectrometry (ICP-AES). It was found that in the presence of PAN, the trace Yb was quantitatively vaporized from a graphite furnace into ICP at a low temperature of 1100 °C. The main factors affecting the formation and vaporization of the Yb-PAN chelate were investigated in detail. Under the optimized conditions, the 3σ detection limit of Yb for this method was 0.4 ng ml⁻¹ and the relative standard deviation (R.S.D.) for 0.1 μg ml⁻¹ Yb was 3.7% (n=9, v=10 μl). The linear range of calibration spanned three orders of magnitude. The content of Yb in the standard reference material (shrub, GBW 07603) determined by the proposed method was in good agreement with the certified value.     

Synthesis and structure of organotin complexes of ytterbium

Reactions of Ph₃SnCl, PhSnCl₃ and Ph₃SnSnPh₃ with ytterbium in THF lead to the formation of the complex (Ph₃Sn₂Yb(THF)₄ (1 * in high yields. According to X-ray data, tin atoms in complex 1 are covalently bonded with the ytterbium atom. Ionic organotin complex of ytterbium [(Ph₃Sn₃Sn]⁻₂[Yb₂Cl₂(DME)₆]²⁺ (2 was synthesised in 75% yield by the reaction of Ph₂SnCl₂ with ytterbium. According to X-ray analysis, the compound consists of [(Ph₃Sn₃Sn]⁻ anions and dimeric ytterbium cations with μ₂-bridged chlorine atoms [(DME) ₃YbClYb(DME₃]²⁺.     

Enhancing the Value of Free Metals in the Synthesis of Lanthanoid Formamidinates: Is a Co‐oxidant Needed?

Treatment of N,N′‐bis(aryl)formamidines (ArFormH), N,N′‐bis(2,6‐difluorophenyl)formamidine (DFFormH) or N,N′‐bis(2,6‐diisopropylphenyl)formamidine (DippFormH), with europium metal in CH₃CN is an efficient synthesis of the divalent complexes: [{Eu(DFForm)₂(CH₃CN)₂}₂] ( Eu1 ) or [Eu(DippForm)₂(CH₃CN)₄] ( Eu2 ). The synthetic method was extended to ytterbium, but the metal required activation by addition of Hg⁰. With DFFormH in CH₃CN, [{Yb(DFForm)₂(CH₃CN)}₂] ( Yb1 ) was obtained in good yield, and [Yb(DFForm)₂(thf)₃] ( Yb3 ) was obtained from a synthesis in CH₃CN/THF. Thus, this synthetic method completely circumvents the use of either salt metathesis, or redox transmetallation/protolysis (RTP) protocols to prepare divalent rare‐earth formamidinates. Heating Yb1 in PhMe/C₆D₆ resulted in decomposition to trivalent products, including one from a CH₃CN activation process. For a synthetic comparison, divalent ytterbium DFForm and DippForm complexes were synthesised by RTP reactions between Yb⁰, Hg(R)₂ (R=Ph, C₆F₅), and ArFormH in THF, leading to the isolation of either [Yb(DFForm)₂(thf)₃] ( Yb3 ), or the first five coordinate rare‐earth formamidinate complex [Yb(DippForm)₂(thf)] ( Yb4 b ), and, from adjustment of the stoichiometry, trivalent [Yb(DFForm)₃(thf)] ( Yb6 ). Oxidation of Yb3 with benzophenone (bp), or halogenating agents (TiCl₄(thf)₂, Ph₃CCl, C₂Cl₆) gave [Yb(DFForm)₃(bp)] or [Yb(DFForm)₂Cl(thf)₂], respectively. Furthermore, the structural chemistry of divalent ArForm complexes has been substantially broadened. Not only have the highest and lowest coordination numbers for divalent rare‐earth ArForm complexes been achieved in Eu2 and Yb4 b , respectively, but also dimeric Eu1 and Yb1 have highly unusual ArForm bridging coordination modes, either perpendicular μ‐1κ(N:N′):2κ(N:N′) in Eu1 , or the twisted μ‐1κ(N:N′):2κ(N′:F′) DFForm coordination in Yb1 , both unprecedented in divalent rare‐earth ArForm chemistry and in the wider divalent rare‐earth amidinate field.     

Yb(OTf)3-catalyzed cyclization of an N-silylenamine with 2-methylene-1,3-cyclohexanedione to afford a 7,8-dihydroquinolin-5(6H)-one derivative and its application to the one-pot conversion to a 2,3,5-trisubstituted quinoline derivative

A catalytic amount of ytterbium triflate (Yb(OTf)₃) promotes the cyclization of an N-silylenamine with in situ generated 2-methylene-1,3-cyclohexanedione and 2-methylenecyclohexanone to produce the corresponding 2,3-disubstituted 7,8-dihydroquinolin-5-one and 5,6,7,8-tetrahydroquinolin-5-one in moderate to good yields. A one-pot conversion of 7,8-dihydroquinolin-5-one to the quinoline derivative also proceeded in good yield.     

Neutron activation analysis of traces in electrolytic zinc sulphate solutions : Part II. determination of molybdenum and rhenium

A neutron activation analysis has been devised for the determination of traces of molybdenum and rhenium in an electrolytic zinc sulphate solution. The activities due to the daughter ^99mTc and to ¹⁸⁶Re were counted. The chemical separation was performed on an anion-exchange resin. The matrix activities were separated by elution with 0.5 N nitric acid. The separation of technetium and rhenium was performed by an elution with 0.2 N perchloric acid. To avoid errors in the molybdenum determination, the uranium present in the sample was separated before the irradiation.     

Koordinationsverhältnisse in Cyclopentadienylverbindungen: I. Die Struktur einer monomeren Ln(CpR)3-Verbindung Tris(methylcyclopentadienyl)ytterbium

Tris(methylcyclopentadienyl)ytterbium(III), Yb(mecp)₃, has been isolated from the reaction of YbCl₃ with Na(MeCP) in THF. The compounds crystallizes in the monoclinic space group Cc with unit cell dimensions a 807.5(2), b 1393.5(3), c 2639.0(5) pm, β 94.55(2)°, and D_calc. 1.841 g cm⁻¹ for Z = 8. There are two molecules in the asymmetric unit cell forming double layers. The ring centroids describe a distorted trigonal geometry around the ytterbium atom.     

Original Potentiometric Ytterbium(III) PVC-Membrane Sensor Based on N1,N2-Bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide

Abstract

In this work, we describe the construction, performance, and applications of an original ytterbium(III) sensor based on N¹,N²-bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide (BHDEH), which acts as a suitable carrier. Because it has a low detection limit of 4.2 × 10^?7 M, the sensor response for the Yb(III) ion is Nernstian over a wide concentration range: four decades of concentration (1.0 × 10^?6 to 1.0 × 10^?2 M). The response time of the electrode is less than 10 s, it can be used in the pH range of 3.2–8.3, and its duration is at least 2 months without any considerable potential divergence. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. To investigate the sensor analytical applicability, it was tested as an indicator electrode in the potentiometric titration of Yb(III) solution with standard EDTA solution. The proposed electrode was also used to determine fluoride ions in mouthwash.     

Erste Pyridylbenzimidazolate der Lanthanide: Synthese,Kristallstruktur und thermischer Abbau von NH4[Ln(N3C12H8)4] mit Ln = Nd,Yb

The First Pyridylbenzimidazolates of the Lanthanides: Syntheses, Crystal Structure and Thermal Decomposition of NH₄[Ln(N₃C₁₂H₈)₄] with Ln = Nd, Yb Transparent yellow crystals of the compounds NH₄ [Ln^III (N₃C₁₂H₈)₄] with Ln = Nd, Yb were obtained by solvent‐free reactions of the lanthanides neodymium and ytterbium with 2‐(2‐Pyridyl)‐benzimidazole. The bulk syntheses lead to isotypic compounds despite the different ionic radii of Nd^III and Yb^III exhibiting nitrogen coordination of the lanthanides only. Both compounds were investigated IR‐ and Raman‐spectroscopically and in regard to their thermal behaviour. They are the first examples of completely solvent‐free (coordinating and non‐coordinating) compounds of the lanthanides with a complete N‐coordination that were obtained via a solid‐state reaction method.