Multibubble sonoluminescence of Tb3+ ion in aqueous solutions of dimethyl sulfoxide

The intensity and spectra of multibubble sonoluminescence of TbCl₃ solutions in water-DMSO mixtures saturated with air and argon are studied. The spectra represent the superposition of the characteristic glow of Tb³⁺ ions and the continuum of emission of electronically excited products of solvent sonolysis (with H₂O*, OH*, and SO₂* as main emitters). Abnormal action of DMSO and sulfur dioxide on the characteristic luminescence of Tb³⁺ ions during sonolysis of aqueous solutions is revealed. These additives enhance the sonoluminescence of water to different extent, quench the sonoluminescence of Tb³⁺, and differently influence the photoluminescence quantum yield of this ion (DMSO acts as activator, whereas SO₂ acts as quencher). Sulfur dioxide quenches the sonoluminescence of Tb3+ much more efficiently than the photoluminescence of Tb³⁺. The abnormal effect of DMSO on sonoluminescence is most probably due to the quenching action of sulfur dioxide formed during sonolysis of DMSO on Tb³⁺* ions in cavitation bubbles.     

On the emitters of sulfuric acid sonoluminescence

A comparative study of the sonoluminescence spectra of water and argon-saturated aqueous H₂SO₄ solutions was carried out. At an H₂SO₄ concentration of 18 mol L⁻¹, the sulfuric acid sonoluminescence is fifty times more intense than water sonoluminescence. The sulfuric acid luminescence spectrum differs from the water sonoluminescence spectrum caused by the emission of excited water molecules and OH radicals from the gas phase of cavitation bubbles. The sulfuric acid sonoluminescence spectrum exhibits maxima at 330, 420, 500, and 630 nm. Emitters of sonoluminescence of sulfuric acid are the singlet (330–340 nm) and triplet (∼420 nm) excited SO₂ molecules formed by sonolysis of H₂SO₄ molecules. Another product of sonolysis of H₂SO₄, atomic oxygen, is assumed to be responsible for the luminescence at λ = 630 nm. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1742–1745, August, 2005.     

Effect of argon on the multibubble sonoluminescence of cerium,terbium, and dysprosium trichlorides

The ultrasonic (20 kHz) multibubble sonoluminescence spectra of aqueous air- or argon-saturated solutions of CeCl₃, TbCl₃, and DyCl₃ were obtained. Saturation with argon leads to the intensity redistribution in the spectrum of the continuum with an increase in its short-wavelength part and increases the intensity of the characteristic emission of Ce³⁺ and Tb³⁺ due to the enhancement of the sonophotoluminescence intensity, i.e., the re-emission of the absorbed part of the continuum by these ions. The Ce³⁺, Tb³⁺, and Dy³⁺ ions quench the OH* emission at 310 nm with a qualitative correlation between the degree of quenching and the standard redox potentials of the pairs Ln^IV/Ln^III. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1797–1802, September, 2008.     

Inverse Perovskites (Eu3O)E with E = Sn,In – Preparation,Crystal Structures and Physical Properties

The cubic inverse Perovskites (Eu₃O)In and (Eu₃O)Sn were prepared from the metals and Eu₂O₃ or SnO₂, respectively. For (Eu₃O)In the crystal structure analysis was performed on single crystal X‐ray diffraction data (space group , a = 512.79(3) pm, Z = 1, R_gt(F) = 0.022, wR(F²) = 0.044). The data indicated full occupancy on all sites and a fully ordered structure. According to magnetic susceptibility measurements and X‐ray absorption spectroscopic data at the Eu L_III edge both compounds contain europium in the 4f⁷ (Eu²⁺) electronic state. (Eu₃O)In orders ferromagnetically at 185(5) K, (Eu₃O)Sn shows antiferromagnetic order at 31.4(2) K. Both compounds behave as metallic conductors in electrical resistivity measurements. However, (Eu₃O)In may be classified a metal, while (Eu₃O)Sn is more likely a heavily doped degenerated semiconductor or semimetal according to the absolute values of the resistivity.     

The influence of the temperature of a liquid on multibubble sonoluminescence of Tb3+ ions in an aqueous solution

The influence of temperature on the yield of multibubble sonoluminescence of Tb³⁺ ions in an aqueous solution of TbCl₃ was studied over the temperature range 5–55°C. The yield monotonically decreased as the temperature increased. The effective activation energy of this temperature quenching was larger than that of photoluminescence of terbium but smaller than for solvent sonoluminescence quenching. The result obtained was explained using the earlier suggested hypothesis of intrabubble f-f excitation of lanthanide ions in the sonolysis of aqueous solutions and two-stage (in the gas and liquid phases) deactivation of their long-lived (longer than 10^?4 s) excited states in a bubble medium.     

Minocycline‐Based Europium(III) Chelate Complexes: Synthesis,Luminescent Properties,and Labeling to Streptavidin

Two chelate ligands for europium(III) having minocycline (=(4S,4aS,5aR,12aS)‐4,7‐bis(dimethylamino)‐1,4,4a,5,5a,6,11,12a‐octahydro‐3,10,12,12a‐tetrahydroxy‐1,11‐dioxonaphthacene‐2‐carboxamide; 5 ) as a VIS‐light‐absorbing group were synthesized as possible VIS‐light‐excitable stable Eu³⁺ complexes for protein labeling. The 9‐amino derivative 7 of minocycline was treated with H₆TTHA (=triethylenetetraminehexaacetic acid=3,6,9,12‐tetrakis(carboxymethyl)‐3,6,9,12‐tetraazatetradecanedioic acid) or H₅DTPA (=diethylenetriaminepentaacetic acid=N,N‐bis{2‐[bis(carboxymethyl)amino]ethyl}glycine) to link the polycarboxylic acids to minocycline. One of the Eu³⁺ chelates, [Eu³⁺(minocycline‐TTHA)] ( 13 ), is moderately luminescent in H₂O by excitation at 395 nm, whereas [Eu³⁺(minocycline‐DTPA)] ( 9 ) was not luminescent by excitation at the same wavelength. The luminescence and the excitation spectra of [Eu³⁺(minocycline‐TTHA)] ( 13 ) showed that, different from other luminescent Eu^III chelate complexes, the emission at 615 nm is caused via direct excitation of the Eu³⁺ ion, and the chelate ligand is not involved in the excitation of Eu³⁺. However, the ligand seems to act for the prevention of quenching of the Eu³⁺ emission by H₂O. The fact that the excitation spectrum of [Eu³⁺(minocycline‐TTHA)] is almost identical with the absorption spectrum of Eu³⁺ aqua ion supports such an excitation mechanism. The high stability of the complexes of [Eu³⁺(minocycline‐DTPA)] ( 9 ) and [Eu³⁺(minocycline‐TTHA)] ( 13 ) was confirmed by UV‐absorption semi‐quantitative titrations of H₄(minocycline‐DTPA) ( 8 ) and H₅(minocycline‐TTHA) ( 12 ) with Eu³⁺. The titrations suggested also that an 1 : 1 ligand Eu³⁺ complex is formed from 12 , whereas an 1 : 2 complex was formed from 8 minocycline‐DTPA. The H₅(minocycline‐TTHA) ( 12 ) was successfully conjugated to streptavidin (SA) (Scheme 5), and thus the applicability of the corresponding Eu³⁺ complex to label a protein was established.     

Eu3F4S2: Synthesis, crystal structure, and magnetic properties of the mixed-valent europium(II,III) fluoride sulfide EuF2·(EuFS)2

Using the method to synthesize rare-earth metal(III) fluoride sulfides MFS (M=Y, La, Ce–Lu), in some cases we were able to obtain mixed-valent compounds such as Yb₃F₄S₂ instead. With Eu₃F₄S₂ another isotypic representative has now been synthesized. Eu₃F₄S₂ (tetragonal, I4/mmm, a=400.34(2), c=1928.17(9) pm, Z=2) is obtained from the reaction of metallic europium, elemental sulfur, and europium trifluoride in a molar ratio of 5:6:4 within seven days at 850 °C in silica-jacketed gas-tightly sealed platinum ampoules. The single-phase product consists of black plate-shaped single crystals with a square cross section, which can be obtained from a flux using equimolar amounts of NaCl as fluxing agent. The crystal structure is best described as an intergrowth structure, in which one layer of CaF₂-type EuF₂ is followed by two layers of PbFCl-type EuFS when sheeted parallel to the (001) plane. Accordingly there are two chemically and crystallographically different europium cations present. One of them (Eu²⁺) is coordinated by eight fluoride anions in a cubic fashion, the other one (Eu³⁺) exhibits a monocapped square antiprismatic coordination sphere with four F⁻ and five S²⁻ anions. Although the structural ordering of the different charged europium cations is plausible, a certain amount of charge delocalization with some polaron activity has to take place, which is suggested by the black color of the title compound. Temperature dependent magnetic susceptibility measurements of Eu₃F₄S₂ show Curie–Weiss behavior with an experimental magnetic moment of 8.19(5) μ_B per formula unit and a paramagnetic Curie temperature of 0.3(2) K. No magnetic ordering is observed down to 4.2 K. In accordance with an ionic formula splitting like (Eu^II)(Eu^III)₂F₄S₂ only one third of the europium centers in Eu₃F₄S₂ carry permanent magnetic moments. ¹⁵¹Eu-Mössbauer spectroscopic experiments at 4.2 K show one signal at an isomer shift of −12.4(1) mm/s and a second one at 0.42(4) mm/s. These signals occur in a ratio of 1:2 and correspond to Eu²⁺ and Eu³⁺, respectively. The spectra at 78 and 298 K are similar, thus no change in the Eu²⁺/Eu³⁺ fraction can be detected.     

Solvent effect on the rate of homogeneous electron exchange of the Eu(III)-Eu(II) system in water-DMF mixtures

The kinetics of homogeneous electron exchange Eu³⁺/Eu²⁺ has been investigated in 1M HClO₄, water+dimethylformamide (DMF) mixed solvent by using labeled europium. Non-monotonic variations of the electron exchange rate constants as a function of the solvent composition was observed.     

The Zintl Phase Eu2Si

The Zintl phase Eu₂Si was synthesized from elemental europium and silicon in a sealed tantalum tube in a high‐frequency furnace at 1270 K and subsequent annealing at 970 K. Investigation of the sample by X‐ray powder and single crystal techniques revealed: Co₂Si (anti‐PbCl₂) type, space group Pnma, a = 783.0(1), b = 504.71(9), c = 937.8(1) pm, wR2 = 0.1193, 459 F² values and 20 variables. The structure contains two europium and one silicon site. ¹⁵¹Eu Mössbauer spectroscopic data show a single signal at an isomer shift of −9.63(3) mm/s, compatible with divalent europium. Within the Zintl concept electron counting can be written as (2Eu²⁺)⁴⁺Si⁴⁻, in agreement with the absence of Si‐Si bonding. Each silicon atom has nine europium neighbors in the form of a tri‐capped trigonal prism. The silicon coordinations of the Zintl phases Eu₂Si, Eu₅Si₃, EuSi, and EuSi₂ are compared.     

Synthesis and characterization thesulphides type ZnS(1-x)MSx

ZnS_(1-x)MS_x(x=0.01 and M=Mn²⁺, Cu²⁺ and Eu²⁺) compounds have been obtained by precipitation from homogeneous solutions of zinc, copper, manganese and europium salts, with S^2- as the precipitating anion, formed by the decomposition of thioacetamide. The thermal study of the milled zinc acetate, thioacetamide, copper acetate, manganese acetate and europium nitrate, respectively, was studied for thermal analyis TG/DSC. XRD respect exhibits a zinc blend crystal structure. This revised version was published online in August 2006 with corrections to the Cover Date.     

Analysis of Ligand Field Effects in Europium(III) Phosphates

Optical spectra (powder reflectance, UV/Vis/NIR region), and temperature dependent magnetic behavior (χ, μ/μ_B) were recorded for the series of anhydrous europium(III) phosphates Eu^III₃O₃(PO₄), Eu^IIIPO₄, Eu^III₂P₄O₁₃, lt- and ht-Eu^III(PO₃)₃, and Eu^IIIP₅O₁₄. By modeling within the AOM framework, the experimental data can be related to the ligand-field splitting experienced by the Eu³⁺ ions in the various mainly low-symmetry coordination environments. Our study confirms the well-established relation e_σ(Eu³⁺–O^2–) ~ d(Eu³⁺–O^2–)^–7.0 between the AOM parameter and the interatomic distance. In addition it is shown that e_σ(Eu³⁺–O^2–) depends strongly on the highly variable polarizability of the oxygen ligator atoms. This polarizability can be related to the optical basicity Λ of the various phosphates.     

Extractive distribution of microamounts of europium and americium in the two phase water — HCl — nitrobenzene — N,N,N′,N′-tetraethyl-2,6-dipicolinamide — hydrogen dicarbollylcobaltate system

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻) in the presence of N,N,N′,N′-tetraethyl-2,6-dipicolinamide (TEtDPA, L) has been investigated. The equilibrium data have been explained assuming that the cations HL⁺, HL₂³⁺, ML₂³⁺ and ML₃³⁺ (M³⁺ = Eu³⁺, Am³⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It has been found that the stability constants of the corresponding complexes EuL _n,org³⁺ and AmL _n,org³⁺, where n = 2, 3 and L is TEtDPA, in the mentioned medium are comparable.     

Extraction of microamounts of europium and americium into nitrobenzene by using hydrogen dicarbollylcobaltate in the presence of N,N′-dibutyl-N,N′-dimethyl-2-(2-dodecyloxyethyl)-malonamide

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻¹) in the presence of N,N′-dibutyl-N,N′-dimethyl-2-(2-dodecyloxyethyl)-malonamide (DBDMDDOEMA, L) has been investigated. The equilibrium data have been explained assuming that the cations HL₂⁺, ML₂³⁺ and ML₃³⁺ (M³⁺ = Eu³⁺, Am³⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It has been found that the stability constants of the corresponding complexes EuL _n ³⁺ and AmL _n ³⁺, where n = 2,3 and L is DBDMDDOEMA, in water saturated nitrobenzene are comparable.     

Reactivity Towards Europium(III) of the Radiolysis Products of the Ionic Liquid 1‐Methyl‐3‐butyl‐1H‐imidazolium Bis[(trifluoromethyl)sulfonyl]amide (C4‐mimTf2N) and Effect of Water: A TRLFS (Time‐Resolved Laser‐Induced Fluorescence Spectroscopy) Preliminary Study

The effect of laser irradiation at λ_exc 266 nm onto the fluorescence characteristics of Eu^III in solution of the ionic liquid 1‐methyl‐3‐butyl‐1H‐imidazolium bis[(trifluoromethyl)sulfonyl]amide (C₄‐mimTf₂N) was examined for various amounts of H₂O added. Stable radiolytic products that were generated at very low doses (in the range of 4 kGy) were very reactive with Eu^III and led to the appearance of a new europium luminescent species that was characterized by lifetime, relative intensity, and emission spectrum. Although the lifetime and the intensity depended on the H₂O content, the emission spectrum was not influenced by H₂O. It was shown that large amounts of H₂O, although not preventing radiolysis of C₄‐mimTf₂N, inhibited the complexation with Eu^III.     

Strong f‐f Excitation and Bright Red Emission in Cd4Gd1‐xEuxO(BO3)3 (0≤x≤1): Near‐UV LED Pumped Red Phosphor with Low Thermal Quenching

Searching efficient red phosphors under near‐UV or blue light excitation is practically important to improve the current white light‐emitting diodes (WLEDs). Eu²⁺‐ and Mn⁴⁺‐based red phosphors have been extensively studied. Here we proposed that Eu³⁺ is also a promising activator when it resides on a noncentrosymmetric coordination site. We proved that Cd₄GdO(BO₃)₃ is a good host, which has a significantly distorted coordination for Eu³⁺. A careful crystallographic study was performed on the solid solutions of Cd₄Gd_1‐xEu_xO(BO₃)₃ (0≤x≤1) by Rietveld refinements. The as‐doped Eu³⁺ cations locate at the Gd³⁺ site and are well separated by CdO₈, CdO₆ and BO₃ groups; thus, only a slight concentration quenching was observed at ≈80 atom % Eu³⁺. Most importantly, the parity‐forbidden law of 4f‐4f transitions for Eu³⁺ are severely depressed, thus the absorptions at ≈393 and ≈465 nm are remarkable. Cd₄Gd_0.2Eu_0.8O(BO₃)₃ can be pumped by a 395 nm LED chip to give a bright red emission, and when mixed with other commercial blue and green phosphors, it can emit the proper white light (0.3657, 0.3613) with a suitable R_a≈87 and correlated colour temperature ≈4326 K. In‐situ photoluminescence study indicated the low thermal quenching of these borate phosphors, especially under 465 nm excitation. Our case proves the practicability to develop near‐UV excited red phosphors in rare‐earth‐containing borates.     

Vibrational Structure of Methacrylates Europium(Iii) and Lanthanum(Iii): Dft and Ir Spectroscopy Study

DFT-D3/PBE0 and IR spectroscopy are employed to study the vibrational structure of europium(III) and lanthanum(III) methacrylates Ln(Macr)₃ (Ln = Eu, La; Macr is the methacrylate anion, CH₂CH(CH₃)COO^–). The calculated geometric and vibrational characteristics are consistent with the experimental data. By means of the calculation of the Eu₂(Macr)₆·(H₂O)₄ complex the experimental IR spectrum is interpreted. The effect of isomorphic lanthanum substitution for the europium ion in the Eu₂(Macr)₆·(H₂O)₄ complex is studied theoretically. A mechanism is proposed for the effect of the vibrational structure on the optical properties (at the isomorphic replacement of the europium ion and temperature elevation).     

Synthesis of europium-doped silica microspheres using the sol–gel microencapsulation method

This paper demonstrates the preparation of europium (Eu³⁺) doped silica microspheres using the W/O microencapsulation method. The water phase (W phase) solution is composed of partially hydrolyzed tetraethyl orthosilicate and acetylsalicylic acid acting as hydrophilic active agents. The Eu(NO)₃·H₂O was added into the W phase solution before mixing with the oil phase solution. Under a controlled stirring treatment, the W/O emulsion is obtained by dispersing the W phase solution in cyclohexene containing Span60 as the surfactant. 3-aminopropyl-triethoxysilane (APTES) is used as a gelling agent to encapsulate the micelles and Eu³⁺ doped silica microspheres with a mean size of around 2???m can be obtained. The experimental parameters, such as the W/O ratio, stirring condition, the amount of APTES added and the temperature, are modified and their effects on the morphology and homogeneity of the resulting Eu³⁺ doped silica microspheres are systematically studied. The Eu³⁺ ions are successfully confined inside the silica microcapsules, exhibiting an optimal red emission with a doping concentration of 3?mol%.     

Europium complex of a tridentate ligand: synthesis and spectroscopic properties

A new europium complex containing the chelate tridentate ligand and imidazole terpyridine (itpy), was synthesized. The complex was characterized by elemental analysis, mass, FT-IR and photoluminescence spectroscopic techniques. The europium complex in solution showed characteristic luminescence properties. The room temperature photoluminescence spectrum of this complex was composed of typical Eu³⁺ red emission assigned to ⁵D₀ → ⁷F₂ transition. The metal-centered red emission seemed to be promoted by the ligand-assisted energy transfer, namely antenna effect.     

Ion beam induced emissions from solid europium compounds

Impact of energetic heavy particles on europium compound surfaces gives rise to radiative optical emission from reflected and sputtered particles and from the excited states of the solid compounds. In the present paper we discuss the optical spectrum and the sputtered secondary ion mass spectrum observed when solid europium oxide (Eu₂O₃) and europium chloride (EuCl₃) are bombarded with 90 keV Ar⁺ ions from an ion accelerator. We observe the reduction reaction in solid europium chloride (EuCl₃) by bombardment with a 20 A/cm² beam of 90 keV Ar⁺ ions.     

Syntheses, structural determination, and binding studies of nine-coordinate mononuclear complexes (EnH2)3[EuIII(Etha)]2 · 11H2O and (EnH2)[EuIII(Egta)(H2O)]2 · 6H2O

Two novel ethylenediaminium salt of europium complexes with aminopolycarboxylic acid ligands, (EnH₂)₃[Eu^III(Ttha)]₂ · 11H₂O (I) (En is ethylenediamine, H₆Ttha is triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (EnH₂)[Eu^III(Egta)(H₂O)]₂ · 6H₂O (II) (H₄Egta is ethyleneglycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) complexes were synthesized, and their crystal structures were determined by single-crystal X-ray diffraction techniques. Both of the two complexes adopt nine-coordinate structures with the pseudo-monocapped square antiprism and crystallize in the monoclinic crystal system with the P2₁/n space group. The crystal data for complex I are as follows: a = 17.8262(8), b = 19.3137(5), c = 20.6233(8) ?, β = 111.301(2)°, V = 6615.3(4) ?³, Z = 8, ρ _c = 1.677 mg/m³, μ = 1.981 mm⁻¹, F(000) = 3432, R = 0.0308, and wR = 0.0737 for 43622 observed reflections with I ≥ 2σ(I). The crystal data for complex II are as follows: a = 12.952(3), b = 12.618(2), c = 14.809(3) ?, β = 105.695(2)°, V = 2330.0(8) ?³, Z = 4, ρ _c = 1.800 mg/m³, μ = 2.765 mm⁻¹, F(000) = 1276, R = 0.0297, and wR = 0.0638 for 18416 observed reflections with I ≥ 2σ(I). One remarkable feature of the two complexes is that the protonated [EnH₂²⁺] cations conjugating to [Eu^III(Ttha)]₂⁶⁻ and [Eu^III(Egta)(H₂O)]₂²⁻ complex anions are reviewed, respectively, which open the path for the Eu^III complexes conjugating with other various biomolecules.