Luminescence study of europium（Ⅲ） tris（β-diketonato）/phosphonate complexes in chloroform

The extraction of Eu（Ⅲ） with β-diketone, HA, and monodentate or bidentate Lewis bases, B, into chloroform and the luminescence properties of the extracted species were studied. Pivaloyltrifluoroacetone, Hpta, and 2-thenoyltfifluoroacetone, Htta, were used as the β-diketones. The Lewis bases, B, were tetraethyl methylene diphosphonate, POPO, which was bidentate, and diethyl benzylphosphonate, PhPO which was monodentate. Based on the extraction data, the stability constants, log β, of the first complexes between tfis（β-diketonato）Eu（Ⅲ） and the phosphonate, EuA3B, were determined to be 6.0 for the POPO complex and 3.40 for the PhPO complex. The Eu（Ⅲ） luminescence intensity in the EuA3POPO was larger than EuA3 where A was either pta or tta at similar concentrations of Eu（Ⅲ）, while that in Eu（pta）3PhPO was stronger than EuA3; however, in Eu（tta）3PhPO, it was weaker than Eu（tta）3. The POPO functions as a sensitizer, and the PhPO functions as a quencher for the tta chelate and as a sensitizer for the pta chelate. From the lifetime and quantum yield, φ, of the Eu（Ⅲ） luminescence in the complexes as well as the observation of the extractability of Eu（Ⅲ） with the Hpta and the phosphonates and of the luminescence spectra of the complexes, it was confirmed that the extraction of Eu（Ⅲ） was remarkably enhanced with a β-diketonate and a strong Lewis base, and also the ternary complex that was formed as the extracted species, showed luminescence enhancement. This phenomenon may be due the formation of a strong bond between the Eu（Ⅲ） and the strong Lewis base leading to more hydrophobicity in the extracted species and also to more effective energy transfer from the Lewis base to the Eu（Ⅲ）. It was not significant whether the donor atoms were N or O.     

Highly luminescent europium and terbium complexes based on succinimide and N-hydroxysuccinimide

The preparation of two highly luminescent europium(III) and terbium(III) complexes with succinimide(SI) and N-hydroxysuccinimide(NHSI) were reported,which were further investigated through elemental chemical analysis,thermal analysis,FT-IR,powder X-ray diffraction,SEM and fluorescence spectroscopy.Data collected through these analysis revealed the formation of the Eu(III) and Tb(III) complexes with the above mentioned ligands at a metal to ligand(M:L) molar ratio of 1:3.Interesting conclusions regarding the efficient sensitization through the coordination site of the lanthanide luminescent centers were retained from the photoluminescent spectra investigation.Strong luminescence emission was observed in case of Eu(III)-SI and Tb(III)-NHSI complexes while the corresponding Eu(III)-NHSI and Tb(III)-SI complexes exhibited no photo luminescent properties.Newly obtained luminescent lanthanide complexes may be of particular interest for various applications in optoelectronics.     

Comparative studies on Y(Ⅲ)and Dy(Ⅲ)extraction from hydrochloric and nitric acids by Cyanex 572 as a novel extractant

Extraction of Y(III) and Dy(III) from hydrochloric and nitric acids by Cy-572 in kerosene was studied. The factors affecting the extraction were separately investigated. The stoichiometry of the extracted species was deduced on the basis of slope analysis method. Evaluation of extraction equilibrium and stripping investigation was studied as well as saponification effect of Cy-572. The composition of the extracted metal species in the organic phase was found to be [MA_3·(HA)_3] for Y(III) or Dy(III) in both media.1.0 mol/L HCI is the best stripping agent for each metal ion from the studied acidic media in one step.Saponified Cy-572 does not exhibit any selectivity towards the extraction of Y(III) or Dy(III) from both HCI and HNO_3 solutions. Based on the obtained results, the data were compared and the separation feasibility between lanthanides and Y(III) in the two media was discussed.     

Separation of Eu（III） with supported dispersion liquid membrane system containing D2EHPA as carrier and HNO3 solution as stripping solution

The Eu(III) separation in supported dispersion liquid membrane (SDLM),with polyvinylidene fluoride membrane (PVDF) as the support and dispersion solution containing HNO3 solution as the stripping solution and Di(2-ethylhexyl) phosphoric acid (D2EHPA) dis-solved in kerosene as the membrane solution,was studied.The effects of pH value,initial concentration of Eu(III) and different ionic strengths in the feed phase,volume ratio of membrane solution and stripping solution,concentration of HNO3 solution,concentration of carrier,different stripping agents in the dispersion phase on the separation of Eu(III) were also investigated,respectively.As a result,the optimum separation conditions of Eu(III) were obtained as the concentration of HNO3 solution was 4.00 mol/L,concentration of D2EHPA was 0.160 mol/L,and volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase,and pH value was 5.00 in the feed phase.Ionic strength had no obvious effect on the separation of Eu(III).Under the optimum conditions studied,when initial concentration of Eu(III) was 1.00×10–4 mol/L,the separation rate of Eu(III) was up to 94.2% during the separation period of 35 min.The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry.The results were in good agreement with the literature data.     

Study on a novel flat renewal supported liquid membrane with D2EHPA and hydrogen nitrate for neodymium extraction

The Nd(III) extraction in flat renewal supported liquid membrane(FRSLM),with polyvinylidene fluoride membrane and renewal solution including HNO3 solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution,was investigated.The effects of pH in the feed phase,volume ratio of membrane solution to stripping solution,concentra-tion of HNO3 solution and concentration of carrier in the renewal phase on extraction of Nd(III) were also studied,respectively.As a result,the optimum extraction conditions of Nd(III) were obtained when concentration of HNO3 solution was 4.00 mol/L,concentration of D2EHPA was 0.100 mol/L,and volume ratio of membrane solution to stripping solution was 1.00 in the renewal phase,and pH was 4.60 in the feed phase.When initial concentration of Nd(III) was 2.00×10-4 mol/L,the extraction percentage of Nd(III) was up to 92.9% in 75 min.     

Photoluminescence and electrochemiluminescence studies of chosen rare earths systems

Eu（Ⅲ） complexes with chosen Keggin polyoxomatalates, POM, containing organic counter cations （tetrabutylarnmonium, tetrabutylphosphonium, triphenylethylphosphonium）, were synthesized, and their photophysical properties were studied. The synthesized complexes had the general formula of XnH5-n[EuSiW11O39], formulated based on the results of elemental and thermogravimetric analysis and FTIR spectroscopy. The photophysical properties of the obtained compounds were investigated using photoluminescence and electrochemiluminescence, ECL, methods in solutions and solids. The most intense luminescence of Eu（Ⅲ） was observed for the complexes with tetrabutylarnmonium cations. After the addition of phenanthroline to the XnH5-n[EuSiW11O39] solutions, a large increase in the Eu（Ⅲ） luminescence intensity and a lengthening of its luminescence lifetime were observed as a result of the formation of ternary complexes. Attempts to apply ECL as a method of light emission by generating species capable of forming excited states in Ln/POMs, i.e., Tb（Ⅲ） and Eu（Ⅲ） in the Na9EuW10O36 and Na9TbW10O36 complexes, were made. The influence of the POM complexes on the ECL was also tested using the Tb/EDDHA （EDDA=ethylenediamine di（o-hydroxyphenylacetic acid）） complex, which is effective in generating ECL.     

Synthesis,spectroscopic characterization,DNA cleavage and antibacterial studies of a novel tridentate Schiff base and some lanthanide（III） complexes

A novel potential tridentate Schiff base was prepared by condensing equimolar quantities of 2-hydroxyacetophenone and 2-aminopyrimidine in methanol. This ligand was versatile in forming a series of complexes with lanthanide ions such as La（III）, Pr（III）, Nd（III）, Sm（III）, Gd（III）, Dy（III） and Yb（III）. The ligand and the metal complexes were characterized through elemental analysis, molar conductance, UV-Visible, IR, 1H NMR, and mass spectral studies. The spectral studies indicated that the ligand was coordinated to the metal ion in neutral tridentate fashion through the azomethine nitrogen, one of the nitrogen atoms in the pyrimidine ring and the phenolic oxygen without deprotonation. Thermal decomposition and luminescence property of lanthanum（III） complex were also examined. The X-ray diffraction patterns showed the crystalline nature of the ligand and its lanthanum（III） complex. The DNA cleavage studies of the ligand and the metal complexes were carried out and it was observed that the lanthanum（III） and neo-dymium（III） complexes cleaved the pUC19 DNA effectively. The ligand and the metal complexes were screened for their antibacte-rial activities. The metal complexes were found to be more potent bactericides than the ligand.     

Relaxation process and phase transition of lanthanide liquid crystalline complexes by photoacoustic spectroscopy

Lanthanide-containing liquid crystals exhibiting smectic A phase close to room temperature were obtained. Photoacoustic （PA） spectroscopy was used to study the spectral properties and phase transitions of liquid crystalline metal complexes. It was found that PA intensity of the ligand had a relationship with the probability of nonradiative transitions, which increased in the order of Eu（tta）3L2〈La（tta）3L2〈 Tb（tta）3L2〈Er（tta）3L2. The relaxation processes of the complexes were studied in depth from two aspects： radiative and non-radiative processes, combining with their fluorescence spectra. Phase transitions of europium（m） and erbium（m） complexes, in the temperature range of 383-358 K, could be clearly monitored by both PA amplitude and PA phase signals. As the temperature crossed the transition point, PA amplitude showed a minimum and PA phase a maximum. The results indicated that PA technique could serve as a new tool for investigating the physicochemical properties of liquid crystals containing metal ions.     

Novel luminescent europium-centered hybrid material covalently grafted with organically modified titania via 2-substituted imidazophenanthroline for fluorescence sensing

By employing a rational approach,we prepared a novel kind of luminescent europium-centered hybrid material named Eu(tta)_3NCP-TiO_2.The resulting material was characterized by FT-IR spectra,SEM,X-ray diffraction,thermogravimetric analysis,and photoluminescence spectra.The hybrid material features the combined advantages of the europium complex and the titania host,exhibiting not only good thermostability,but also long luminescence lifetime.Owing to the excellent luminescence of this material,the application in detecting organic small molecule solvents and metal ions was explored systematically.Significantly,Eu(tta)_3 NCP-TiO_2 exhibits superior detection for nitrobenzene molecule and Cu~(2+) ion in DMF(N,N-dimethylformamide) medium.Furthermore,the limit of detection(LOD) of Eu(tta)_3 NCP-TiO_2 for nitrobenzene and Cu~(2+) ion can be counted as 5.593× 10~(-5) and 9.566 ×10~(-5) mol/L,respectively.The results demonstrate that Eu(tta)_3 NCP-TiO_2 can serve as an efficient fluorescence probe for the detection of sensing of nitrobenzene and Cu~(2+) ion.     

Synthesis of novel europium complexes and their photoluminescence properties

Two novel luminescent Eu(III) complexes with the formulas(NIP)Eu(DBM)3 1 and(ENIP)Eu(DBM)3 2(NIP=2-(naphtha-len-1-yl)-1H-imidazo [4,5-f] [1,10] phenanthroline,ENIP=1-ethyl-2-(naphthalen-1-yl)-1H-imidazo [4,5-f] [1,10] phenanthroline,DBM= dibenzoylmethanato) were successfully synthesized and characterized by IR and elemental analysis.The UV-vis absorption spectra and pho-toluminescence properties of the complexes were investigated,and the irradiation at the absorption band between 300-400 nm of europium complexes either in solution or in the solid state led to the emission of a sharp red band at ~610 nm,a characteristic Eu3+ emission due to the transition of 5D0→7F2.Furthermore,the weak emission bands around 587 and 595 nm attributed to 5D0→7F0 and 5D0→7F1 transition were also displayed in the emission spectra.These results demonstrated that the Eu(III) ion was sensitized efficiently by the ligand and displayed photoluminescence with high intensity,narrow half-peak width,and monochromic light.The excited-state lifetimes of 1 and 2 were in the microsecond time scale,but the photoluminescence quantum yield of 2(0.03) was two times higher than that of 1(0.01) which should be at-tributed to the effect of the ethyl substituting in ENIP.     

Synthesis and spectral characterization of lanthanide complexes with 1,2-diphenyl-4-butyl-3,5-pyrazolidinedione： Luminescent property of Tb（Ⅲ） complex

The complexes of rare earth elements with 1,2-diphenyl-4-butyl-3,5-Pyrazolidinedione (PBH, phenylbutazone) were synthesized and characterized by elemental analysis, molar conductance, IR, UV-Vis, EPR and magnetic moment measurements. Based on these studies the complexes were formulated as [Ln(PB)3(H2O)2]?nH2O, where Ln=Eu(III), Gd(III), Tb(III), Dy(III) and Er(III). From IR spectra, it was found that PBH acted as a bidentate mono-ionic ligand coordinating through two carbonyl oxygen of the pyrazolidinedione ring. The thermal analysis of all the complexes was carried out at a heating rate of 10 oC/min. The kinetic aspects of the complexes were evaluated. The nega-tive entropy value of the complexes indicated a more ordered state for the activated complexes. The photoluminescence property of Tb(III) complex was investigated. It showed all the characteristic emission peaks of Tb3+ with a life time of 0.98914 ms.     

Extraction and separation of Nd(Ⅲ), Sm(Ⅲ), Dy(Ⅲ), Fe(Ⅲ), Ni(Ⅱ), and Cs(Ⅰ) from concentrated chloride solutions with N,N,N’,N’-tetra(2-ethylhexyl) diglycolamide as new extractant

The feasibility of using N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide(TEHDGA) in 75 vol.% n-dodecane-25 vol.% n-octanol as agents for the extraction and separation of Nd(III), Sm(III), Dy(III), Fe(III), Ni(II), and Cs(I) from concentrated chloride solution was investigated. Different extraction behaviors were obtained towards rare earth elements(REE) studied and Fe(III), Ni(II) and Cs(I). Efficient separation of Nd(III), Sm(III) and Dy(III) from Fe(III), Ni(II), and Cs(I) was achieved by TEHDGA, depending on the HCl, HNO3 or H2SO4 concentration. A systematic investigation was carried out on the detailed extraction properties of Nd(III), Sm(III), and Dy(III) with TEHDGA from chloride media. The IR spectra of the extracted species were investigated.     

Synthesis, structure and spectroscopic studies of europium complex with S（＋）-mandelic acid

The Eu3+ complexes with S(+) -mandelic acid were synthesized in the form of powders by mixing aqueous solutions of EuCl3,S(+) -mandelic acid and NaOH in different molar ratios.The powders were characterized by elemental analysis,X-ray powder diffraction(XRPD) method,Fourier transform infrared(FTIR) and Raman spectroscopy,UV-vis reflectance and luminescence spectra as well as lumi-nescence lifetime measurements.It was found that all studied powders of Eu3+ complexes with S(+) -mandelic acid were isostructural and crystalline and formed compounds with the formula Eu(Man) 3(H2O) 2.     

Synthesis and luminescent properties of novel pyrazolone rare earth complexes

A novel pyrazolone pyridine-containing ligand,2,6-bis(1-phenyl-4-ethoxycarbonyl-5-pyrazolone-3-yl)pyridine (H2L) was de-signed and synthesized from pyridine-2,6-dicarboxylic acid (1),and its Eu(III) and Tb(III) complexes were prepared.The ligand and com-plexes were characterized in detail based on FT-IR spectra,1H NMR,elemental analysis and thermal analysis,and the formula of Ln2L3·4H2O (Ln=Eu or Tb) of rare earth complexes was confirmed.The UV-vis absorption spectra and photoluminescence properties of the complexes were investigated,which showed that the Eu(III) and Tb(III) ions could be sensitized efficiently by the ligand (H2L) and emit the photolumi-nescence with high intensity,narrow half-peak width,and monochromic light.The results indicated that the complexes showed potential as excellent luminescent materials.     

Synthesis and Photoluminescence Properties of Rare Earth Complexes with 3-Allyl-2, 4-Pentanedione

In order to combine the merits of rare earth organic complexes with excellent material performances of polymers,a polymerizable chelating agent, 3-allyl-2, 4-pentane dione (APD), was synthesized by phase transfer catalysis and its rare earth complexes were prepared. The compounds were characterized by EA, IR and ^1H NMR. Their UV spectra and fluorescence spectra were investigated. The effects of allyl on the luminescence properties of the complexes were studied.The results show that the sensitization of APD is changed by allyl in comparison with that of acetyl acetone (acac), and it becomes an ideal novel ligand of Eu. In addition, intramolecular energy transfer mechanism in the luminescence process in the complexes was also discussed in detail.     

Photophysical properties of a new ternary europium complex with 2-thenoyltrifluoroacetone and 5-nitro-1,10-phenanthroline

A ligand, 5-nitro-1,10-phenanthroline (phenNO2), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR and 1H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (36.0%) upon ligand excitation and a long 5D0 lifetime (458 μs), which indicated that the ligand phenNO2 could sensitize the luminescence of Eu(III) ion efficiently.     

Synthesis and photoluminescent properties of doped ternary Eu_(1-x)Ln_x(NPPD)_3·DPQ complexes

Rare earth (RE) ternary complexes of Eu0.5Ln0.5(NPPD)3·(DPQ) (HNPPD=1-(naphthalen-2-yl)-3-phenylpropane-1,3-dione; DPQ= dipyridobenzoquinone) and Eu1-xLax(NPPD)3·(DPQ) (Ln3+=La3+, Gd3+, Sm3+, Pr3+; x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9) were synthesized by the reaction of RECl3·6H2O with HNPPD and DPQ in stoichiometry. The complexes were characterized with IR, elemental analysis, TGA-DSC and wide-angle X-ray diffraction. The UV-Vis absorption spectra and fluorescence properties of the complexes were also investigated. The experimental results showed that the luminescence efficiency of Eu3+ complexes was enhanced by doping some other lanthanide ions. Eu0.7La0.3(NPPD)3·(DPQ) showed the highest luminescence efficiency.     

Efficient extraction and stripping of Nd(Ⅲ),Eu(Ⅲ) and Er(Ⅲ) by membrane dispersion micro-extractors

The extraction of low concentration rare earth elements at high phase ratio was investigated. The traditional extraction set-up, such as mixer-settler, have drawbacks of easy emulsification, difficult separation and low efficiency if operated at the above condition. Membrane dispersion micro-extractor,owing to its well-dispersed, high surface-to-volume ratio and fast mass transfer rate, was employed in our work. Nd(Ⅲ),Eu(Ⅲ),Er(Ⅲ) were chosen to represent light, medium,heavy rare earth elements(REEs). The extraction process of REEs with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507) was investigated by membrane dispersion micro-extractors. Firstly, the extraction equilibrium of these three elements was explored in the stirred conical flasks, and it is indicated that the extraction efficiencies can be 0.95, 0.97 and 0.98, respectively within 40 min at phase ratio of 100:1. Then the effects of operational conditions such as the residence time, organic and aqueous flow rates on extraction efficiency were also explored in micro-extractors. The results indicate that the efficiency decreases and then increases if increasing aqueous phase flow rate, residence time and droplets' diameter are the key factors of this process. Increasing the phase ratio reduces the extraction efficiency significantly. When the REEs solution has an initial pH of 4.00, the flow rates of continuous and dispersed phase are 40 and 1.6 mL/min,respectively, and 90 mg/L Nd(Ⅲ), Eu(Ⅲ) and Er(Ⅲ) is extracted by 1 mol/L P507 at the out-let length of8 m. The extraction efficiencies are 0.978,0.983 and 0.991, respectively. Finally the stripping process was also studied with the micro-extractor. The stripping efficiencies of Nd(Ⅲ), Eu(Ⅲ) and Er(Ⅲ) can reach0.99, 0.96 and 0.91, respectively when the out-let length is 8 m and the concentration of hydrochloric acid is 1 mol/L. The developed approach offers a novel and simple strategy on the fast extraction and enrichment of low concentration rare earth elements from waste water.     

Polystyrene microsphere-based lanthanide luminescent chemosensor for detection of organophosphate pesticides

Fluorescent microspheres of polystyrene-based Eu(Ⅲ) complexes were prepared from TentaGel resin,2,6-bisbenzimidazolylpyri-dine and europium nitrate. The microspheres were characterized by FTIR spectroscopy, elemental analysis, XPS measurements and fluores-cence spectroscopy. Characteristic red emission under irradiation of365nm light from a hand-held UV lamp was observed for the micro-spheres either in a solution or solid-state.Fluorescent quenching was observed when the microspheres were exposed to a trace amount of di-ethyl chlorophosphate (DCP)in the dispersion. The material and property can be potentially used to fabricate chemosensor in the detection of organophosphates.     

Extraction and Stripping of Ytterbium (Ⅲ) from H2SO4 Medium by Cyanex 923

The extraction and stripping of ytterbium(Ⅲ) from sulfuric acid medium using Cyanex 923 in heptane solution was investigated. The effects of extractant concentration, pH and sulfate ion as well as stripping agents, acidity and temperature on the extraction and stripping were studied. The equilibrium constants and thermodynamic parameters, such as ΔH (10.76 kJ·mol-1), ΔG (-79.26 kJ·mol-1) and ΔS (292.41 J·K-1·mol-1), were calculated. The extraction mechanism and the complex species extracted were determined by slope analysis and FTIR spectra. Furthermore, it was found that the extraction of Yb (Ⅲ) from sulfuric acid medium by Cyanex 923 increased with pH, concentration of SO42-, HSO4-, and extractant concentration, and approximately a quantitative extraction of Yb(Ⅲ) was achieved at an equilibrium pH near 3.0, and the extracted complex was YbSO4(HSO4)·2Cyanex923(o).