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.     

Solution and Thermodynamic Studies on Binary and Ternary Complexes of Lanthanides

The interactions of La(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), and Yb(Ⅲ) with cytosine, 5-bromocytosine, 5-azacytosine and 5-flurocytosine as primary ligands (L) and guanine (A) as secondary ligand for both binary (1:1) as well as ternary (1:1:1) systems were investigated by potentiometric equilibrium measurements at 25, 35 and 45 ℃ in aqueous solution (ionic strength, μ=0.1 mol·dm-3 NaNO3). The stability constants of the binary (1:1) and ternary (1:1:1) metal-ligand complexes follow the following order La＜Pr＜Nd＜Sm＜Eu＞Gd＜Dy＞Yb. Results also indicate that the ternary lanthanide complexes of La(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), and Yb(Ⅲ) are more stable than corresponding binary lanthanide complexes. The enthalpy (Δhof) and entropy (Δsof) changes for the formation of binary and ternary complexes were calculated from temperature coefficient data. The ΔΔSof values are positive for all the metal ligand systems. The negative ΔΔHof values indicate the extra stability of the ternary complexes by the exothermic enthalpy changes (ΔΔSof=ΔTSof-ΔBSof and ΔΔHof=ΔTHof-ΔBHof where ΔTSof, ΔTHof and ΔBSof, ΔBHof are the entropy and enthalpy values associated with the ternary and binary complexes, respectively). It was also proposed that the guanine is bonded to metal ions through N1/C6=O and N7 whereas cytosine and its derivatives are bonded through N3 atoms in ternary complexes.     

Structure regulation for ultra-high luminescence quantum yield lanthanide complex and simultaneous detection of cancer marker and ferrous ion

The exploitation of a highly selective and sensitive probe to detect both cancer marker and metal ion is of great importance.In this work,the "one stone two bird" agent of 1,10-phenanthroline(phen) is designed to disrupt the polymeric lanthanide MOFs(LnMOFs,[Ln(CHO_2)_3]n,Ln=Tb,la;Eu,1 b,CHO2=formic acid) {[Ln(CHO_2)_4·(C_2 H_8 N)]_n,Ln=Y,2 a;Gd,2 b;Dy,2 c,C_2 H_8 N=dimethylamine}) into a soluble mononuclear species [Ln(phen)2(NO_3)_3,Ln=Tb,3 a;Eu,3 b] as well as to provide an antenna for efficient photons absorption,resulting in an ultra-high luminescence quantum yield(QY,90%) europium complex.The luminescence QY is among the highest record of monomeric(zero-dimensional) lanthanide complexes.Furthermore,mononuclear Tb3+complex(3 a) functions as a multiplex sensor towards both Fe2+and cancer marker of 5-hydroxyindole-3-acetic acid(5-HIAA).Importantly,the limit of detection(LOD)for sensing 5-HIAA is an ultra-sensitive value of 1 × 10 s mol/L,which is even lower than that necessary for the early diagnosis of carcinoid tumors.More interestingly,sensing results in simulated urine reveals that 3 a has potential application for early diagnosis in the clinic.     

Preparation and Properties of Rare Earths with 6-Methyl-2-Picolinic Acid N-Oxide and 2,2'-Bipyridine-N,N'-Dioxide

A series of new ternary complexes of 6-methyl-2-picolinic acid N-oxide(HL) and 2,2'-bipyridine-N,N'-dioxide(bipyO2) with Ln3+(Ln=La, Sm, Eu, Gd, Tb, Dy, Yb) were synthesized and characterized. The composition of the ternary complexes is determined as {LnL3·bipyO2·H2O} (n-1)H2O (n=2.5～3.0). They are nonelectrolytes in ethanol. It is found that fluorescence intensities of the ternary complexes, LnL3·bipyO2·H2O, are weaker than those of binary complexes, LnL3·H2O. And it is also found that Tb3+ luminescence at 489.3 nm in TbL3·bipyO2·H2O is sensitized by bipyO2, and it is stronger than that at 543.8 nm, Which differs from TbL3·H2O.     

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 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.     

Structure of Complexes of Lanthanides with N, N＇-Dimethyl-3-Oxa-Glutaramic Acid

A new stripping agent N, N-dimetbyl-3-oxa-glutaramic Acid (DOGA) was used in TRPO process to simplify the TRPO process. The structures of the complexes of the DOGA with Eu(Ⅲ), Nd(Ⅲ), La(Ⅲ) were characterized with extended X-ray absorption fine structure spectroscopy (EXAFS), infrared spectra (IR) and mass spectra (MS). The molecular formula of the complexes of Eu( Ⅲ ) and Nd( Ⅲ ) is deduced to be M(DOGA)3, and only La( Ⅲ ) can form the complex HM(DOGA)4 under condition of high consistency of the DOGA. The coordination number of Ln( Ⅲ ) in the complexes is 8, and all of coordinated donor atoms are O atoms. For Eu( Ⅲ ), Nd( Ⅲ ), the coordination numbers of O atom in the first coordination shell is 6 and the average coordination bond lengths of Ln - O are 0.240 nm, 0.244 nm respectively,while the numbers of the second O shell are 2.4, and the average coordination bond lengths of Ln - O are 0.260 nm,0. 262 nm. For La( Ⅲ ), the coordination numbers of O atom in the first coordination shell is 6 and the average coordination bond lengths of La - O are 0.258nm, while the number of O atom in the second coordination shell is 4.4, and the average coordination bond length of La - O is 0.28 nm. The results of IR and MS show that there is no water coordinating with Ln( Ⅲ ) in the complexes.     

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.     

Syntheses and Infrared Spectra of Rare Earth Complexes with Diethyl Phosphate

The title complexes Ln(DEP),(Ln=La,Sm,Eu,Ho and Yb)were synthesized by reaction of triethylphosphate with trivalent rare earth chlorides.The mechanism of thermo-decomposition of the complexes hasbeen studied.According to their IR spectra,the residues of the thermo-decomposition of the complexes wereidentified as Ln(PO_3)_3.Their IR spectra were measured and principal IR bands were assigned.The experimentalresults of the IR spectra of the complexes show that the title complexes have the same coordination form and mo-lecular configuration as rare earth,e.g.Sm,complex with dimethyl phosphate(Sm(DMP)_3).Each of the rareearth ion links three rare earth ions nearby through double“O-P-O”bridges to form a special network ofrings-linking-rings,each of which consists of twenty-four atoms.The Ln-O bond is principally ionic.     

Synthesis of two lanthanide clusters Ln_4~Ⅲ(Gd_4 and Dy_4) with [2×2] square grid shape:Magnetocaloric effect and slow magnetic relaxation behaviors

Two isostructural tetranuclear lanthanide clusters named [Ln_4(L)_4(CH_3 O)4]·CH_3 OH(Ln=Gd(Ⅲ) for 1,Dy(Ⅲ) for 2,H_2 L=N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl) picolinohydrazide) were successfully isolated by using a polydentate Schiff based ligand and Ln(Ⅲ) nitrate salts.The structures of 1 and 2 were characterized by X-ray structural analyses,they are held by four double deprotonated ligands L~(2-).In them all the lanthanide ions are eight-coordinated and distributed over four vertices of a parallelogram,presenting a Ln4 cluster with a strict [2 × 2] square grid pattern.The details of magnetic analysis show that 1 displays weak anti-ferromagnetic exchange between neighboring Gd(Ⅲ) ions through carboxylate oxygen and methanol oxygen ligand atoms.Furthermore,1 exhibits significant magnetocaloric effect with the maximum entropy change-ΔS_m value of 28.5 J/(kg K) for ΔH=7.0 T at 2.0 K.For compound 2,remarkable slow magnetic relaxation behaviors are observed in the presence of zero magnetic field with τ_0=1.02 × 10~(-6) s and energy barrier ΔE/k_B=43.24 K.     

Physico-chemical properties of 3-methoxy-2-nitrobenzoates of some rare earth elements（Ⅲ）

The complexes of 3-methoxy-2-nitrobenzoates of Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Er(III) and Tm(III) with the formula: Ln(C8H6NO5)3·2H2O, where Ln=lanthanides(III), were synthesized and characterized by elemental analysis, Forier transform irtrared (FTIR) spectroscopy, magnetic and thermogravimetric studies and also by X-ray diffraction (XRD) measurements. The complexes had col- ours typical for Ln(III) ions. The carboxylate groups bound as bidentate chelating. On heating to 1173 K in air they decomposed in the same way, at first, dehydrated in one step to anhydrous salts, and then decomposed to the oxides of respective metals with intermediate formation of the oxycarbonates. The enthalpy values of the dehydration process changed from 133.72 to 44.50 kJ/mol. Their solubility in water at 293 K was of the order of 10-4 mol/dm3. The magnetic moments of analysed complexes were determined by Gouy’s method in the range of 76-303 K.     

Synthesis and characterization of aminophenolate-ligated rare-earth metal amide complexes and their catalytic activity for lactides polymerization

Amine elimination of Ln[N(SiMe_3)_2]_3(μ-Cl)Li(THF)_3 with aminophenol H[ON] {H[ON]=2-(CH_2 NC_5 H_(10))-4,6-~tBu_2-C_6 H_3OH} in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]_2 LnN(SiMe_3)_2(Ln=Yb(1),Y(2),Gd(3),Sm(4),Nd(5)) in 57%-73% isolated yields.All these complexes were characterized by elemental analysis.The molecular structures of complexes 1-4 were determined by single crystal X-ray diffraction.These complexes are highly active for L-Iactide polymerization to give high molecular weight polymers with unimodal molecular weight distributions.In addition,these complexes can also initiate rac-lactide polymerization with high activity to afford heterotactic-rich polylactides.     

Voltammetric Study on the Complexes of the Rare Earths with Tetraphenylporphyrin

Fifteen rare earth-tetraphenylporphyrin(RE-TPP)complexes were directly prepared by mixing equalmolar concentrations of RE(ClO_4)_3 and H_2TPP in acetone media.The electrochemical behaviors of these com-plexes and the influence of dissolved oxygen were investigated by voltammetry.Althrough there are some differ-ence between the behaviors of light and heavy rare earth-porphyrins,the central RE ions of the all fifteen com-plexes were reduced from tervalent to divalent state,meanwhile the dissovled oxygen was reduced as superoxideion O~-.which readily combined with the complex forming peroxide additive complex such as RE-TPP·O~(2-)_2.     

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.     

Syntheses,characterization, and luminescence of two lanthanide complexes [Ln2（acetate）6（HeO）4]·4H2O （Ln=Tb（1）, Sm（2））

Two dinuclear compounds [Ln2（acetate）6（H2O）4]-4H2O （Ln=Tb（1）, Sm（2）） were obtained by the hydrothermal reaction of Ln2O3 with malonic acid at 150 ℃. Both compounds were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction. The results showed that complexes 1 and 2 were isomorphous and crystallize in triclinic space group P 1. The coordination geometry around Ln（Ⅲ） ions in the complexes 1 and 2 was a distorted tricapped trigonal prism with a nine coordination. In the crystal, the molecular organization was further stabilized by well-defined weak hydrogen bonding interactions between the neutral dinuclear molecular units that led to the formation of a three-dimensional network. The fluorescence properties of the two complexes 1 and 2 in organic solvents were also studied. The results show that the ligand acetate favored energy transfer to the emitting energy level of Tb（Ⅲ） in complex 1. Some factors that influence the fluorescent intensity were also discussed in the article.     

Microwave assisted synthesis, spectroscopy and biochemical aspects of lanthanum(Ⅲ) and praseodymium(Ⅲ) complexes with oxadiazole functionalised dithiocarbazinates

The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyses, elec-trical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass spectra. Nephelauxetic ratio, covalency parameter and bonding parameter for these complexes were also calculated. The probable structures of the complexes were proposed. The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds.     

Synthesis of rare earth metal-organic frameworks （Ln-MOFs） and their properties of adsorption desulfurization

The rare earth metal-organic frameworks(Ln-MOFs) materials,Ln(BTC)(H2O)·(DMF),were synthesized using the rare earth metal(Ln=Sm,Eu,Tb,Y) and 1,3,5-trimesic acid(BTC) as a metal ion center and ligand,respectively.X-ray diffraction(XRD) and infrared spectroscopy(FT-IR) were employed to characterize the Ln-MOFs structural features.The property of adsorption desulfurization of Ln-MOFs materials was evaluated with thiophene/n-octane as model oil.The results showed that Ln-MOFs with rare earth metals Sm,Eu,Tb and Y had perfect crystalline and good adsorption desulfurization ability.Y(BTC)(H2O)·(DMF) material had a comparatively better activity for the adsorption desulfurization with desulfurization rate up to 80.7% and the sulfur adsorption capacity was found 30.7 mgS/g(Y-MOFs).The Ln-MOFs materials had excellent reusability.     

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,fluorescence properties of Tb(Ⅲ) complexes with novel mono-substituted β-diketone ligands

Two novel pyridine-2,6-dicarboxylic acid derivatives of mono-β-diketone named methyl 6-biphenylacetyl-2-pyridinecarboxylate (MBP) and 6-biphenylacetyl-2-pyridinecarboxylic acid (BAA) and their corresponding binary complexes Tb(MBP)3.6H2O and Tb(BAA)3·6H2O were synthesized. The ligands were characterized by elemental analysis, FT-IR and 1H-NMR, and the complexes were characterized with elemental analysis, FT-IR, 1H-NMR and thermogravimetric and differential thermal analysis(TG-DTA). The investigation of fluorescence properties of the complexes Tb(MBP)3·6H2O and Tb(BAA)3·6H2O showed that the introduction of the biphenyl enlarged the π-conjugated system of the ligands and enhanced the luminescent intensity of the complexes. The Tb(Ⅲ) ion could be sensitized more efficiently by the ligands, in particular, the fluorescence intensity of the complex Tb(BAA)3·6H2O was about 20% higher than that of Tb(MBP)3·6H2O and 30% higher than that of Tb(Ⅲ) complexes with bis-β-diketone-type ligands that we have previously reported.     

Microwave assisted synthesis, spectroscopic, thermal, and antifungal studies of some lanthanide(Ⅲ) complexes with a heterocyclic bishydrazone

A bishydrazone formed by the condensation of isatinmonohydrazone and salicylaldehyde reacted with lanthanide(Ⅲ) chloride to form complexes of the type [Ln(HISA)2Cl3], where, Ln=La(Ⅲ), ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sin(Ⅲ), Eu(Ⅲ), or Gd(Ⅲ) and HISA=[(2-hydroxybenzaldehyde)-3-isatin]bishydrazone. Both reactions were carried out under microwave conditions. The ligand and the 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 ligand acted as neutral tridentate, coordinating through the carbonyl oxygen, azomethine nitrogen, and phenolic oxygen without deprotonation. The ligand and lanthanum(Ⅲ) complex were subjected to X-ray diffraction studies. The X-ray diffraction pattern of ligand exhibited its crystalline nature and that of the lanthanum(Ⅲ) complex indicated its amorphous character. The thermal decomposition behaviour of the complex, [La(HISA)2Cl3], was examined in the temperature range of 40-800 ℃ using TG, DTG, and DTA. The ligand and the metal complexes were screened for their antifungal activities.