Hydroxyl-and-carboxyl ligand concatenating multi-lanthanide substituted tellurotungstates and electrochemical detection of noradrenaline

Developing and exploring organic–inorganic hybrid multi-lanthanide (Ln) implanted heteropolyoxometalates (HPOMs) has bloomed into an emerging research field. In this article, two neoteric d-gluconic acids (H₆GA) concatenating multi-Ln^III implanted heteropolytungstates K₁₄H₁₀[Ln₄(H₂O)₄W₆(H₂GA)₄O₁₂(B-α-TeW₉O₃₃)₄]·60H₂O (Ln = La³⁺ (1), Pr³⁺ (2)) were obtained in acidic aqueous system. Attractively, in the polyanion structure of 1 and 2, six W^VI and four Ln^III centers are connected by four flexible H₂GA^4? ligands via carboxyl and hydroxyl groups, resulting in the heterometallic [Ln₄(H₂O)₄W₆(H₂GA)₄O₁₂]⁸⁺ cluster and then the heterometallic cluster is surrounded by four [B-α-TeW₉O₃₃]^8– segments. Electrochemical measurements for the 1@CFMCN/GCE sensor (CFMCN = carboxyl-functionalized multiwalled carbon nanotube; GCE = glass carbon electrode) demonstrate that 1@CFMCN/GCE shows benign recognition response to detecting noradrenaline (NDA). This research expands the structural diversity of Ln-implanted HPOMs and presents an electrochemical platform of recognizing NDA in the field of biosensors.     

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.     

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.     

Crystal structures and fluorescence properties of lanthanide complexes prepared with 2,2’-biphenyldicarboxylic acid and 2,2’：6’,2’’-terpyridine

Five lanthanide complexes of Ln₂(dpdc)₂(tpy)₂(NO₃)₂(H₂O)₂ [Ln=La (1), Ce (2), Pr (3), Sm (4), Gd (5), H₂dpdc=2,2’-biphenyldicarboxylic acid and tpy=2,2′:6′,2″-terpyridine] were prepared at room temperature and characterized by X-ray diffraction, FT-IR and thermo-gravimetric analysis. The results showed that complexes 1–5 were isostructural and consisted of dinuclear units [Ln₂(dpdc)₂(tpy)₂(NO₃)(H₂O)₂] bridged by two dpdc^2? ligands. The dinuclear units with strong intramolecular hydrogen bonds were assembled into 2D supramolecular layers by the weak π^…π staking interactions between pyridine rings of tpy. The TG analysis showed that the complexes 1–5 behaved higher thermal stability with no mass loss at < 320 °C. The lanthanide contraction effect and the solid state luminescence properties of complexes 1–5 were also investigated. The luminescence emission spectra of complexes 1–5 exhibited ligands emission bands and complex 3 and 4 had no typical emission in the visible region.     

Tetranuclear yttrium and gadolinium 2-acetylcyclopentanoate clusters: Synthesis and their use as spin-coating precursors for metal oxide film formation for field-effect transistor fabrication

Lanthanide clusters [Ln_4(μ_3-OH)_2(η~2-accp)_4((μ-O)-η~2-accp)_6](Ln = Y(4),Gd(5); accp = 2-acetylcyclopentanoate) are accessible by treatment of [M(NO_3)_3·6 H_2 O](M = Y(1),Gd(2)) with 3 equiv. of Haccp(3) in presence of NaOH. The molecular structures of 4 and 5 in the solid-state are discussed. The thermal behavior of 4 and 5 was studied by TG under Ar and O_2, showing multistep decomposition processes. Additionally, DSC studies were carried out under an atmosphere of O_2. PXRD measurements of the TG residues confirm the formation of Ln_2 O_3.Spin-coating experiments were carried out with 4 and 5 for Ln_2 O_3 film deposition on silicon substrates. The layers are smooth, close and are of thicknesses of 18.87±1.13 nm and 25.59 ± 4.55 nm for Ln = Y and Gd, which was evidenced by SEM and EDX studies. Field-effect transistors were successfully fabricated by deposition of carbon nanotubes on top of the Y_2 O_3 films and formation of palladium contacts by a lift-off procedure. An on/off ratio of more than 4 orders of magnitude is achieved without considerable leakage currents. These results demonstrate the potential use of spin-coated Y_2 O_3 as a gate dielectric in electronic devices.     

Synthesis, crystal structures and characterization of a pair of TbIII-based enantiomers

A pair of novel Tb^III-based enantiomers, [Tb(dbm)₃·L_SS] (1) and [Tb(dbm)₃·L_RR] (2) (where L_SS=(+)-4,5-pinene bipyridine, L_RR= (-)-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 Tb^III ion was eight-coordinated by six O atoms of three dbm ligands and two N atoms from one chiral ligand L_SS or L_RR. The CD spectra revealed that complexes 1 and 2 were enantiomers. Thermogravimetric analysis results indicated that 1 and 2 were thermally stable up to 246 °C.     

Metal-organic frameworks of lanthanide iminodiacetates and tartrates:Synthesis,structural characterization and luminescence properties——Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Two series of lanthanide-containing metal-organic frameworks(Ln-MOFs) of the general formula{[Ln(HIDA)_2 H_2 O]ClO_4·H_2 O}_n(Ln = La(1),Nd(2),Eu(3),Gd(4),Tb(5),Eu:Tb(6);H_2 IDA=iminodiacetic acid) and [Ln(TT)(HTT)(H_2 O)_3]_n(Ln=Eu(7),Gd(8),Tb(9),Dy(10),and Eu:Tb(11);H_2 TT=tartaric acid)were synthesized by reacting Ln(ClO_4)_3 with iminodiacetic acid and L-tartaric acid,respectively.All compounds were structurally characterized by single-crystal X-ray diffraction.Elemental analyses are co nsistent with the corre sponding crystallographically generated formulas.Mo reover,the luminescence properties of both the single and mixed-lanthanide complexes were studied.Near infrared,red,and green emissions that are characteristic of Nd(Ⅲ),Eu(Ⅲ),and Tb(Ⅲ) are observed for 2,3/7,and 5/9,respectively.For the two mixed-lanthanide complex systems 6 and 11,depending on the relative amount of Eu(Ⅲ) and Tb(Ⅲ),the color of emission can be fine-tuned.It is found that a small amount of Eu(Ⅲ) is adequate for the observation of the most intense transition of Eu(Ⅲ).This is believed to be a result of energy transfer from Tb(Ⅲ) to Eu(Ⅲ) within the same complex-a conclusion supported by the significantly shortened lifetime of Tb(Ⅲ) and the accompanying enhanced lifetime of Eu(Ⅲ) in the mixedlanthanide complex with respect to the corresponding values for the pure Tb(Ⅲ) and Eu(Ⅲ) complexes with the same ligand.     

Construction of NIR luminescent nanoscale lanthanide complexes with new flexible Schiff base ligands

Four mono-and bi-nuclear lanthanide complexes [LnL~1(No_3)(H_2O)DMF](Ln=Nd(1) and Yb(2)) and[Ln_2(L~2)_2(OAc)_2](Ln=Nd(3) and Yb(4)) were synthesized by using two new Schiff base ligands with long(CH_2)_2 NH(CH_2)_2 backbone.The lengths of the Schiff base ligands are about 1.8 nm.The bi-nuclear lanthanide complexes 3 and 4 have nanoscale structures with sizes of approximately 0.7 nm×1.1 nm×1.6 nm.For 3,the molar ratio of Nd:Br:O obtained by the energy dispersive X-ray spectroscopy analysis is in agreement with the crystal structure.The chromogenic Schiff base ligands in1-4 can efficiently transfer energy to lanthanide ions,thus,these complexes exhibit the typical NIR luminescence of lanthanide ions.Interestingly,3 and 4 have higher NIR emission quantum yields(Φ_(em))than 1 and 2,respectively.     

Synthesis of pyrrolidinyl-ethylene fluorenyl rare-earth metal complexes and catalysis for 2-vinylpyridine polymerization

The metathesis reaction between pyrrolidinyl-ethylene fluorenyl lithium salts with in situ prepared cationic rare-earth metal dialkyl species [Ln(CH₂SiMe₃)₂(THF)_x][BPh₄] afford efficiently the corresponding constrained-geometry complexes L¹Ln(CH₂SiMe₃)₂(L¹=FluCH₂CH₂NC₄H₈,Ln=Y(1a),Lu(1b),Sc(1c)) and L² Ln(CH₂SiMe₃     

Synthesis and crystal structure of a 1D chainlike rare earth coordinated tungstogermenate： [（CH3）4N]1.50H3.50[Gd（GeW11O39）（H2O）2]·2.5H2O

A 1D zigzag polyoxometalate [(CH3)4N]1.50H3.50[Gd(GeW11O39)(H2O)2]·2.5H2O(1) was synthesized by reaction of the monova-cant polyanion [α-GeW11O39]8- with Gd3+ ions in aqueous solution and characterized by IR, UV spectra, ICP, and X-ray crystallography. X-ray single-crystal structural analysis indicated that the title compound crystallized in a monoclinic lattice, C2/c space group with α=2.8201(5), b=2.2885(3), c=2.4033(4) nm,β=123.875 (2)°, V=12.878(4) nm3, Z=8, R1=0.0623, wR2=0.1287. The solid-state structure of the title compound displayed an infinite one-dimensional arrangement built up of [α-GeW11O39]8- polyanions connected by GdⅢ cations.     

Hydrothermal synthesis and structural studies of a new coordination polymer of lanthanum（III） with benzene-1,2,4,5-tetracarboxylic acid and 4,4＇-bipyridine

A new lanthanum complex formulated as {(bpyH₂)[La(btc)(H₂O)₄(NO₃)]·2H₂O}_n (1) (btcH₄=benzene-1,2,4,5-tetracarboxylic acid; bpy=4,4′-bipyridine) was hydrothermally synthesized. The complex was characterized by FT-IR spectroscopy, elemental analysis and X-ray diffraction. X-ray crystal structural analysis revealed that the compound belonged to the monoclinic space group C2/c with cell parameters a= 1.42806(7) nm, b=1.10258(5) nm, c=1.60333(8) nm and β=101.9400(10)°. The complex was polymeric with La^III atoms linked by four O atoms from two carboxylate groups of one benzene-1,2,4,5-tetracarboxylate. The La^III atom was ten coordinated in a distorted tetracapped trigonal prism. In the crystal structure, a wide range of noncovalent interactions consisting of hydrogen bonding (of the types of O—H…O, N—H…O and C—H…O) and ion pairing interactions connected the various components into a supramolecular structure.     

Synthesis and Characterization of A Polynuclear Yttrium Trifluoroethoxide and Its Activity for Oligomerization of Phenyl Isocyanate

A polynuclear yttrium trifluoroethoxide was synthesized and its activity for the oligomerization of phenyl isocyanate was tested. Reaction of anhydrous YCl3 with CF3CH2ONa in a 1:3 molar ratio in THF at room temperature, after workup, gave complex 1 as colorless crystals. The composition of complex 1 is [Y(OCH2CF3)3]6ONa2(THF)12, which was identified by elemental analysis and 1H NMR. Further X-ray structure determination reveals that complex 1 is a polynuclear ion pair compound, [Y6(μ6-O)(OCH2CF3)18]2-[Na(THF)6] 2 (1). The crystal data of complex 1 are trigonal, P-3 space group, a=1.78440(14) nm, b=1.78440(14) nm, c=1.27395(12) nm, γ=120°, V=3.5129(5) nm3, Z=1, Dc=1.607 mg·m-3, μ=2.591 mm-1 (Mo Kα), F(000)=1710, R=0.067, wR=0.182. Preliminary results demonstrated that complex 1 is a highly effective catalyst for the oligomerization of phenyl isocyanate.     

Studies of two lanthanide coordination polymers built up from dinuclear units

The two three-dimensional oxo-bridged lanthanides , with Ln=Ho3+ (1); Gd3+ (2), are isomorphous. They have layer-type structures built up from non-centrosymmetric dinuclear unit Ln2O12(H2O)4, beside three lattice H2O molecules stabilizing the 3D open-framework. The building entities are linked through one classical syn-anti μ2-carboxylato-K1O:K1O’ bridge. Within the bi-polyhedra, two double μ2-O’; K2O,O’ bridges and a syn-syn classical one, support the magnetic measurements carried out on holmium compound indicating relatively weak anti-ferromagnetic interactions. The comparison with magnetic studies on the almost similar reported Gd(III) compound, suggested that concomitant antiferromagnetic and ferromagnetic properties could not be excluded. The two distinct thermal behaviors evidenced the higher metal-water bond strength with the smaller cation, and revealed the great supramolecular effects generated by hydrogen-bonding patterns.     

Influence of bidentate structure of an aryl phosphine oxide ligand on photophysical properties of its EuIII complex

The bidentate phosphine oxide ligand 1,8-bis(diphenylphosphino) naphthalene oxide (NAPO) and its Eu^III complex 1 Eu(TTA)₃(NAPO) (TTA=2-thenoyltrifluoroacetonate) were chosen to study the effect of bidentate phosphine oxide ligand on the photophysical properties of the corresponding complex. The intramolecular energy transfer processes of 1 were studied. The investigation showed that with bidentate structure NAPO could suppress solvent-induced quenching by enforcing the ligand-ligand interaction and the rigidity of the complex. Contrasted with the monodentate triphenylphosphine oxide (TPPO), NAPO had a higher first triplet excited energy level (T₁) and a lower first singlet excited energy level (S₁), which fitted to the corresponding excited energy levels of anion ligand TTA much more and supported more efficient singlet and triplet energy transfer in its Eu^III complex.     

Synthesis, Characterization, and Reactivity of Amine Bis（phenolato） Cyclopentadienyl Lanthanide Complexes

（C5H5）3Ln（THF）reacted with amine bis（phenol） LH2 [ L = Me2NCH2CH2N {CH2-（2-O-C6H2-But^1-3-Me- 5）}2 ] in a 1：1 molar ratio in THF to generate the amine bis（phenolato） cyclopentadienyl lanthanide complexes LLn（C5H5） （THF）·（THF）,（Ln = La （1）, n =0; Ln = Sm（2）, n = 1） in high yields. Complexes 1 and 2 were fully characterized by elemental analysis, NMR （for 1） and IR spectra, and X-ray structural determination. The crystal data of complex 1 are monoclinic, P21/c space goup, a= 1.1595（1） nm, b = 1.8588（2） nm, c = 1.6647（1） nm, β = 98.490（2）°, V =3.5486（5） nm^3, Z =4, Dc = 1.338 mg· m^3,μ = 1240 mm^-1, F（000）= 1488, R =0.0249, wR = 0.0568. The crystal data of complex 2 are monoclinic, P21/c sp ace goup, a = 0.9692 （1） nm, b = 1.4583 （2） nm, c = 2.8192 （3） nm, = 96.805 （2）°, V = 3.9584 （7） nm^3, Z=4, Dc =1.340 mg · ma, μ = 1.524 mm^-1, F（000）= 1668, R =0.0346, wR =0.0756. The attempts failed to synthesize the amine bis（phenolate） lanthanide alkoxides by the reactions of complexes 1 and 2 with alcohols. The preliminary results revealed that complex 1 can initiate ε-caprolactone polymerization.     

Novel lanthanide coordination polymers based on mixed N,O-donor ligands and their visible-light-driven photocatalytic performance

In the present work,we prepared three isostructural lanthanide(Ln) coordination polymers(CPs).namely [Ln(Hhpc)(phen)(NO₃)](Ln=Gd(1),La(2),Y(3),H₃ hpc=5-hydroxy-1 H-pyrazole-3-carboxyIic acid,phen=1,10-phenanthroline) by hydrothermal method.Their structures were characterized by single crystal X-ray diffraction,Fourier transform infrared spectrum,elemental analysis,powder X-ray diffraction and thermal gravimetric analysis.CPs 1-3 are isostrutural and exhibit two-dimensional(...     

Synthesis of two lanthanide clusters LnIII4 (Gd4 and Dy4) with [2 × 2] square grid shape: Magnetocaloric effect and slow magnetic relaxation behaviors

Two isostructural tetranuclear lanthanide clusters named [Ln₄(L)₄(CH₃O)₄]·CH₃OH (Ln = Gd(III) for 1, Dy(III) for 2, H₂L = 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 L²⁻. 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 τ₀ = 1.02 × 10⁻⁶ s and energy barrier ΔE/k_B = 43.24 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.     

Substituent effects on novel lanthanide(III) hydrazides complexes

New lanthanide (Eu³⁺ and Gd³⁺) complexes were successfully synthesized and the effect of the p-phenyl substituent on the Eu³⁺ luminescent properties was evaluated. In this sense, benzhydrazide, p-toluic hydrazide, 4-hydroxybenzhydrazide and 4-aminobenzoic hydrazide were used as ligands and the complexes were obtained by mixing the lanthanide salts with hydrazides in ethanol at room temperature and keeping the reaction for 2 h under mechanical stirring. Crystal of Gd-amino was obtained and its structure was elucidated by single-crystal X-ray diffraction, revealing that Gd³⁺ centered in a distorted tricapped trigonal-prismatic molecular geometry. IR spectroscopy and the elucidated structure confirm hydrazides acting as bidentate ligands binding to Ln³⁺ ions through the oxygen of carbonyl group and the nitrogen of terminal amine, forming a five-membered ring. CHN analyses confirm the molecular formulas [Gd(amino)₄(H₂O)](NO₃)₃·(C₂H₅OH) and [Eu(toluic)₃(H₂O)₃](NO₃)₃. Lower T₁ state energies are observed for ligands p-substituted with higher electron donating capacity groups, such as p-NH₂ and p-OH. In contrast, higher lifetimes and quantum efficiencies are obtained for Eu³⁺ complexes with ligands p-H and p-CH₃ substituted, which are not deactivator groups.     

Application of three Ln(Ⅲ)-coordination polymers in fields of luminescence,antibacteria and detection of Fe3+ and 4-nitrophenol

Three lanthanide-based coordination polymers(Ln-CPs) with layered structure,{[La₂(L)₃(DMF)(H₂O)₃]·H₂O}_n(1),{[Eu₂(L)₃(DMF)₂(H₂O)]·(H₂O)}_n(2){Tb₂(L)₃(DMF)₂(H₂O)]·H₂O}n(3) were successfully synthesized from H₂L(N,N’-bis(4-carbozylbenzyl)aniline).Remarkably,compound 3 has extremely high sensitivity to 4-n...