Synthesis and structure of a praseodymium (Ⅲ) complex with carboxylate ligand:A thermal and spectroscopic study

One Pr(Ⅲ) lanthanide ion complex was initially synthesized and characterized by TGA-DSC in air atmosphere, as well as characterized by CHN elemental analysis, defining the stoichiometric ratio as Pr(DMBz)_3. The gaseous products evolved during the thermal decomposition were also monitored in N_2 atmosphere employing TGA/FT-IR system. A crystal structure is obtained by state-of-the-art powder X-rays diffraction methods measured in conventional laboratory equipment and refined by the Rietveld method, which defined it as a monoclinic system of the space group P2_1/C with a polymeric crystal structure, [Pr(DMB_Z)_3]_n. FT-IR theoretical spectrum and time-dependent density functional theory(TD-DFT) were calculated from TGA-DSC and crystalline system data. The experimental and theoretical FT-IR spectra present a high correlation degree when the main stretching bands are compared, while the energy transfer(HOMO — LUMO) in their neighborhoods suggests the main contributions of the light-emitting states.     

Synthesis, structure and photoluminescent properties of a new Eu(Ⅲ) complex with 5-bromoisophthalic acid

The self-assembly of 5-bromoisophthalic acid (H2BIPA) with Eu(NO3)3·6H2O under the hydrothermal conditions gave a 3D coordination polymer, Eu2(BIPA)3(CH3CH2OH) (1), which was characterized by elemental analysis, IR and single-crystal X-ray diffraction. Complex 1 displayed an unusual three-dimensional network of a rare (4,6)-connected (48.66.8)2(44.62)2(42.84) topology, which was different from Eu2(BDC)3(H2O)2 (BDC=isophthalate), because the -Br substituent of the isophthalate resulted in the different electronic effects and the steric hindrance to change the coordination modes of carboxylate groups in the assembled process. Moreover, the luminescent properties of 1 were also investigated in the solid state.     

Synthesis, spectroscopic characterization and thermal studies of some lanthanide(Ⅲ) nitrate complexes with a hydrazo derivative of 4-aminoantipyrine

A heterocyclic ligand synthesized by the coupling of diazotized 4-aminoantipyrine with acetylacetone reacted with lanthanide(III) nitrate to form complexes of the type [Ln(HAAP)₂(NO₃)₃] where, Ln=La(III), Ce(III), Pr(III), Nd(III), Sm(III), or Gd(III) and HAAP= 3-{[2-(N-1-phenyl-2,3-dimethylpyrazol-3-in-5-on-4-yl)]hydrazone}pent-2,3,4-trione. The ligand and metal complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, UV-Visible, infrared, far infrared and proton NMR spectral data. The spectral data revealed that the ligand existed in the hydrazo form and coordinated to the metal ion without deprotonation in a neutral tridentate manner, through carbonyl oxygen of pyrazolone ring, hydrazo nitrogen and carbonyl oxygen of the acetylacetone moiety. The molar conductance values adequately supported their non-electrolytic nature. The ligand and the praseodymium(III) complex were subjected to X-ray diffraction studies. Thermal decomposition behavior of the lanthanum(III) complex was also examined.     

Synthesis, crystal structure and characterization of one-dimension complex constructed by terbium(Ⅲ) and 2-iodobenzoate

The complex of [Tb(2-IBA)3(H2O)2]n (2-IBA=2-iodobenzoate) was prepared by solvent method from TbCl36H2O and 2-iodo-benzoic acid. The crystal structure was determined with X-ray single-crystal diffraction. The X-ray diffraction analysis indicated that the title complex crystallized in triclinic crystal system and Pi space group. The Tb3+ ion was coordinated by six oxygen atoms from five 2-IBA ligands and two oxygen atoms from two water molecules, giving a distorted square-antiprism polyhedral geometry. The carboxyl groups were bonded to the Tb3+ ions with bidentate-bridging and bidentate-chelating coordination modes. The adjacent Tb3+ ions were linked by two bidentate-bridging 2-IBA ligands, forming I-D chain structure. The fluorescence spectrum of the complex showed four main peaks at 489, 543, 587, and 618 nm, Corresponding to 5D4→7F (J=6-3) transition emissions of the Tb3+ ion, respectively.     

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.     

Syntheses and fluorescent properties of complexes of Eu(Ⅲ) with HTTA,TPPO and benzoic acid

A series of Eu(Ⅲ) complexes of α-thenoyltrifluoroacetone(HTTA) with trioctylphosphine oxide(TPPO) and benzoic acid(BA) or its two derivatives, p-toluic acid(PTA) and p-methoxybenzoic acid(POA) were synthesized and were characterized with elemental analysis, IR spectroscopy, scanning electronic microscopy and fluorescent spectra. The complexes were revealed to be Eu(BA)(TTA)2TPPO2, Eu(PTA)(TTA)2TPPO2 and Eu(POA)(TTA)2TPPO2. The excitation and absorption spectra of the complex Eu(POA)(TTA)2TPPO2 in MeOH solution were investigated in detail. The experimental result showed that relatively cheap materials with sharp red luminescence could be pre-pared, when benzoic acid or its two derivatives were added in Eu(Ⅲ) complexes of α-thenoyltdfluoroacetone with trioctylphosphine oxide. The relative fluorescence intensity of the Eu(Ⅲ) complexes decreased in the following order: Eu(POA)(TTA)2TPPO2> Eu(PTA)(TTA)2TPPO2>Eu(BA)(TTA)2TPPO2.     

Synthesis,crystal structures and characterization of a pair of Tb~Ⅲ-based enantiomers

A pair of novel TbIII-based enantiomers,[Tb(dbm)3·LSS] (1) and [Tb(dbm)3·LRR] (2) (where LSS=(+)-4,5-pinene bipyridine,LRR= (–)-4,5-pinene bipyridine,dbm=dibenzoylmethanate),were synthesized and characterized based on single crystal X-ray diffraction,elemental analysis,FT-IR,TG and CD spectra.X-ray diffraction analysis showed that both the complexes crystallized in monoclinic crystal system with P21 chiral space group.The TbIII ion was eight-coordinated by six O atoms of three dbm ligands and two N atoms fr...     

Using europium(Ⅲ) complex of 1,4,7,10-tetraazacyclododecane-1,4,7-triacedic acid Eu.DO3A as a luminescent sensor for bicarbonate

Sensing of analyte s in biological fluids and biotechnological production media remains a challenge.He re,the luminescent response of the europium(III) complex of 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid(DO3A) to bicarbonate was investigated in detail.The response of Eu.DO3A to changes in bicarbonate concentration was studied in different buffers,and the influence of ionic strength,pH,and specific ions was determined.The response is found to depend on pH and ionic strength,but it is not possible to separate contributions from the sensing event from those in the bicarbonate activity.Prior to demonstrating the ability to determine the bicarbonate concentration in bioproduction media and serum,the influence of competing carboxy anions was evaluated.It is established that while competing anions bind stronger to the responsive complex,at the relevant concentration their contribution to the recorded signal is negligible.We are thus able to conclude that Eu.DO3A is a good platform for building a bicarbonate sensor.     

Hydrothermal synthesis, crystal structure and magnetic properties of a Dy~Ⅲ-Fe~Ⅲ heteronuclear complex

A new 3d-4f heteronuclear complex [Fe(phen)3]2[FeDy(H2O)(tiron)3]·6H2O (1,Na2H2tiron=disodium 4,5-dihydro-xybenzene-1,3disulfonate) was synthesized by the hydrothermal reaction. The complex crystallized in the cubic system, space group P213 with the cell parameters:a=2.18786(14)nm, V=10.4727(12)nm3 , Z=4, F(000)=4720, R1=0.0493, wR2 =0.1165, S=1.05. In each [FeDy(H2O)(tiron)3]6-unit, it was revealed that the Fe3+ ion was in a FeO6 distorted trigonal anti-prism coordination polyhedron completed by six phenolate O atoms from three tiron 4- ligands, while Dy3+ in a DyO7 distorted monocapped trigonal anti-prism coordination polyhedron completed by three phenolate μ2-O atoms and three O atoms from sulfonate groups of three ligands and one O atom from water. The magnetic properties of the complex was determined in the range of 2-300K, indicating the antiferromagnetic interaction between the central DyIII-FeIII ions.     

Synthesis,spectral characterization,thermal and biological studies of lanthanide(Ⅲ) complexes of oxyphenbutazone

Lanthanide(III) complexes of 4-butyl-1-(4-hydroxyphenyl)-2-phenyl-3,5-pyrazolidinedione(OPB) were prepared by homogeneous precipitation. The solid complexes were characterized by elemental analysis, magnetic susceptibility data, molar conductivity measurements and IR, UV-Vis, mass,1H NMR and13C NMR spectral methods. The thermal decomposition of the complexes under static air atmosphere was investigated by simultaneous TG/DTG at a heating rate of 10 °C/min. The final decomposition products were found to be metal oxides. The spectroscopic data suggested that OPB acted as a bidentate, mono-ionic ligand coordinating through two carbonyl oxygens of the pyrazolidinedione ring. The kinetic and thermodynamic parameters such as activation energy, pre-exponential factor and entropy of activation for each step of the decomposition reactions were evaluated using Coats-Redfern and MacCallum-Tanner equations. The negative entropy values of the complexes indicated that the activated complexes had a more ordered structure than the reactant and that the reactions were slower than normal. Investigations of antimicrobial activity of the compounds were carried out by the disk diffusion technique.     

Cytotoxicity of new Ho(Ⅲ) and Pr(Ⅲ) complexes

New complexes of coumarin-3-carboxylic acid(HCCA) with Ho(Ⅲ) and Pr(Ⅲ) were synthesized and their structures and spectral properties were investigated by elemental analysis,IR,Raman and NMR measurements.According to the experimental data the complexes’ formula and geometries were suggested.Vibrational frequencies,IR intensities and Raman activities as well as 1H NMR chemical shifts of HCCA and its Ho(Ⅲ) and Pr(Ⅲ) complexes were presented.The comparative experimental vibrational and NMR analyses of both the ligand and the Ln(Ⅲ) complexes predicted the bidentate binding to Ho(Ⅲ) and Pr(Ⅲ) through the deprotonated carboxylic oxygen and the carbonylic oxygen of the ligand.The cytotoxic/cytostatic properties of the ligand and the newly synthesized complexes of coumarin-3-carboxylic acid with Ho(Ⅲ) and Pr(Ⅲ) were tested by MTT reduction assay against two mouse tumor cell lines:melanoma B16 and fibrosarcoma L929.They were also tested for cytotoxicity against normal mouse peritoneal macrophages.The proliferation inhibitory effect of the complexes compared to that of the ligand proved their cytotoxic/cytostatic properties against both the tumor cell lines.In addition,the complexes were less cytotoxic against normal mouse macrophages and were able to modulate NO release by activated macrophages.The obtained results were in accordance with our previously published data concerning the activity of lanthanide(Ⅲ) complexes with other coumarin derivatives.     

Synthesis, spectroscopic characterization, and thermal decomposition kinetics of some lanthanide(Ⅲ) nitrate complexes of 2-(N-o-hydroxyacetophenone) amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene

Complexes of La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), Yb(Ⅲ), and Lu(Ⅲ) with 2-(N-o- hydroxyacetophenone)amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene (HAAT) formed by the condensation of o-hydroxyacetophenone and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene were synthesized and characterized on the basis of elemental analyses, molar conductance measurements, magnetic susceptibility data, UV-Visible, IR, and NMR spectral studies. The spectral data revealed that the ligand acted as a neutral tridentate coordinating to the metal ion through ONO donor sequence. A coordination number nine was proposed for the complexes. Thermal decomposition studies of the ligand and lanthanum(Ⅲ) complex were carried out and kinetic parameters were calculated using Coats-Redfern equation. The decomposition reactions followed random nucleation mechanism with one nucleus on each particle.     

Preparation and characterization of Ce_(0.8)La_(0.2–x)Y_xO_(1.9) as electrolyte for solid oxide fuel cells

In this study, ultrafine Ce0.8La0.2–x Y x O1.9（for x=0, 0.05, 0.10, 0.15, 0.20） powders were successfully prepared by the sol-gel method.The samples were characterized by fourier transform infrared（FTIR）, thermogravimetric and differential scanning calorimetry（TG-DSC）, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, AC impedance and thermal expansion measurements.Experimental results indicated that highly phase-pure cubic fluorite electrolyte Ce0.8La0.2–x Y x O1.9 powders were obtained after calcining at 600 °C.The as-synthesized powders exhibited high sintering activity, the Ce0.8La0.2–x Y x O1.9 series electrolytes which have higher relative densities over 96% could be obtained after sintered at 1400 °C for 4 h.Ce0.8La0.15Y0.05O1.9 electrolyte sintered at 1400 °C for 4 h exhibited higher oxide ionic conductivity（σ800 oC=0.057 S/cm）, lower electrical activation energy（E a=0.87 e V） and moderate thermal expansion coefficient（TEC=15.5×10-6 K-1, temperature range 25–800 °C）.     

Fluorescence enhancement of Tb(Ⅲ) complex with a new β-diketone ligand by 1,10-phenanthroline

A novel β-diketone, 1-(3,4,5-trisbenzyloxy)benzoyl-5-benzoyl acetylacetone (TBAA), and its corresponding binary Tb(Ⅲ) complex Tb(TBAA)3·2H2O and ternary complex Tb(TBAA)3Phen with 1,10-phenanthroline (Phen) were prepared. The ligand was characterized based on elemental analysis, FT-IR, and 1H NMR. The complexes were characterized with elemental analysis, FT-IR and thermogravimetry and derivative thermogravimetry (TG-DTG). Photoluminescence measurements indicated that the energy absorbed by the organic ligan...     

Characterization, crystal structure and luminescence properties of a new europium(Ⅲ) complex with macrocyclic ligand derived from 2,6-diformyl-4-methylphenol and diethylenetriamine

The title compound (13,27-dimethyl-3,6,9,17,20,23-hexaazatricyclo-[23.3.1.111,15]-triaconta-1(29),2,9,11,13,15(30),16,23,25,27-decaene-29,30-diol-N3, N6, N9, O29, O30)-bis (nitrato-O,O')-europium (Ⅲ) nitrate hydrate ([EuL(NO3)2(NO3).H2O, L denotes the macrocyc-lic ligand) was prepared and characterized by elemental analysis, infrared spectra, and electrospray mass spectra. Its crystal and molecular structure was determined by X-ray diffraction. The crystal crystallized in the monoclinic system, space group C2/c with a=2.3757 (4) nm, b=1.4302(3) nm, c=1.9584(3) nm, β=91.654(5)°, M=S18.60, V=6.651(2) nm3, Z=8,D=1.635 g/cm, F(000)=3312, R=0.0542, wR=0.1045. The central ion Eu3+ was nine-coordinated in the coordinaton geometry of a distorted tricapped trigonal prism. The macrocycle was coordi-nated through two oxygen and three nitrogen atoms. Two nitrate are chelate in the opposite positions of the macrocycle, the third nitrate be-ing ionic. At room temperature, excitation of the title complex gave rise to the characteristic emissions of the Eu3+ ion.     

Extraction kinetics and kinetic separation of La(Ⅲ),Gd(Ⅲ),Ho(Ⅲ) and Lu(Ⅲ) from chloride medium by HEHEHP

Acco rding to the tetrad-effect,14 elements of lanthanides can be divided into four groups.In our previous study,a new approach was proposed for the kinetic separation of four rare earth ions La(Ⅲ),Gd(Ⅲ),Ho(Ⅲ) and Lu(Ⅲ) coming from four groups.In that study,four rare-earth ions were kinetically separated from their coexisting mixed aqueous solutions,by performing liquid-column elution using the aqueous solution containing four lanthanide rare-earth ions as the stationary phase and the dispersed organic oil droplets containing HEHEHP(2-ethyl hexyl phosphonic acid mono 2-ethyl hexyl ester) extractant as the mobile phase.The study of extraction kinetics is very important for understanding the kinetic separation of rare earth ions,which was carried out in this paper.The extraction kinetics of La(Ⅲ),Gd(Ⅲ),Ho(Ⅲ) and Lu(Ⅲ) by HEHEHP diluted in heptane were investigated using single drop method.The different parameters affecting the extraction rate such as column length,specific interfacial area,rare earth ion concentration,extractant concentration,hydrogen ion concentration and temperature were separately studied and the rate equations are deduced.It is first order with respect to rare earth ion and HEHEHP concentrations,and negative first order with respect to hydrogen ion concentrations.The rate constants at 293.15 K are 10~(-6.23),10~(-5.73),10~(-5.58) and 10~(-5.43),respectively.The experimental results demonstrate that the extraction rate of La(Ⅲ), Gd(Ⅲ),Ho(Ⅲ) or Lu(Ⅲ) is diffusion-controlled,and the extraction reaction takes place at the interface rather than in the bulk phase.The extraction model was proposed.Besides,the kinetic separation of rare earth ions by HEHEHP oil drops was discussed.     

Pairs of Ln(Ⅲ) dopant ions in crystalline solid luminophores: an ab initio computational study

Formation of dopant ions clusters in solid(glass) luminophores may affect efficiency of non-radiative energy transfer processes between dopant(photoactivator) ions via shortening of the effective distance between them. This study was based on the assumption that the distance between the dopant ions affects the energy of crystal volume at proximity. According to this idea, semi-empirical and ab initio density functional theory(DFT) calculations were performed on various supercells of YVO_4:Eu~(3+) as a model system. It was noted that a shorter Eu–Eu distance resulted in lower total energy of the system, compared to an analogous structure with distant Eu~(3+) ions. As lower energy configurations are preferred, the observed phenomenon was considered to be related to dopant ions clusters formation. Additionally, the values of energies obtained from DFT calculations were used to estimate the percentage of dopant ions occurring as pairs, for different dopant concentrations. The estimation agreed quite well with the available literature data.     

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.     

Synthesis and luminescence properties of rare earth ternary complexes consisting of Eu(Ⅲ), β-diketones and 1,10-phenanthroline

Three novel β-diketones (HPPP, HTPP, and HFPP) ligands were synthesized by Sonogashira coupling reaction and Claisen con-densation. The structure of β-diketones was confirmed with elemental analysis, IR, NMR and MS spectra. Three new ternary complexes consisting of Eu(Ⅲ), β-diketones, and 1,10-phenanthroline(phen) were synthesized and characterized as ThL3phen (L=PPP, TPP, FPP) with elemental analysis, chemical analysis, and IR spectra, and their luminescence properties were studied.     

Synthesis, characterization and fluorescence of N,N'-BIS (6-metyl-2-pyridine-carboxylamide-N-oxide)-1,2-ethane and corresponding rare earth (Ⅲ) complexes

A new ligand, N,N-BIS (6-metyl-2-pyridinecarboxylamide-N-oxide)-1,2-ethane (L) and six lanthanide(III) complexes (RE=La, Sm, Eu, Tb, Gd, Yb) were synthesized and characterized in detail. The results indicated that the composition of the binary complexes was determined as [REL(H₂O)(NO₃)₂]NO₃·nH₂O (n=0–2), and the Eu³⁺ complex had bright red fluorescence in solid state. Three complexes of Eu³⁺, Tb³⁺, and Gd³⁺ with 6-methylpicolinic acid N-oxide (L') were also synthesized. The relative intensity of sensitized luminescence for Eu³⁺ increased in the following order: L>L'. The phosphorescence spectra of the Gd³⁺ complexes at 77 K were measured. The energies of excited triplet state for the ligands were 20704 cm⁻¹ (L) and 20408 cm⁻¹ (L'). The facts that the ligands sensitized Eu³⁺ strongly and the order of the emission intensity for Eu³⁺ complexes were explained by ΔE(T-⁵D). This meant that the triplet energy level of the ligand was the main factor to influence RE³⁺ luminescence.