Tetranuclear Eu(III)-Co(II) complex of an N4O4 macrocycle

The reaction of an Eu(III) complex of the protonated form of the macrocyclic Schiff base derived from 1,3-diamino-2-hydroxypropane and 2,6-diformylphenol, [Eu(H₄L)Cl₃], with three equivalents of base results in a mononuclear complex of the triply deprotonated form of the ligand, [Eu(HL)]. The photophysical properties of the [Eu(HL)] complex are discussed on the basis of emission and excitation spectra, as well as of the emission decay times. The [Eu(HL)] complex in a reaction with cobalt(II) chloride gives a heterometallic Eu(III)-Co(II) macrocyclic complex, [EuCo(HL)(CH₃OH)₂Cl]₂Cl₂·4CH₃OH. In the presence of base and an excess of cobalt(II) chloride the starting [Eu(H₄L)Cl₃] complex is converted to a dinuclear Co(II) complex, [Co₂(H₂L)Cl₂(CH₃OH)₂]·1.5CH₃OH.     

Hetero-bimetallic 2D coordination network constructed by azacrown ether carboxylic acid with lanthanide(III) and sodium ions

Two lanthanide-based coordination polymers [Na₃La(L)Cl·(H₂O)₆]·NO₃ (La-L) and [Na₃Eu(L)Cl·(H₂O)₆]·NO₃ (Eu-L) were newly synthesized by reaction of an azacrown ether carboxylic acid ligand H₄L (4,7,13,16-tetracarboxymethyl-1,10-dioxa-4,7,13,16-tetraazacyclooctadecane) with La(III)/Eu(III). Complexes La-L and Eu-L exhibited two-dimensional (2D) coordination architectures built up by Ln–L coordinating subunits and one-dimensional (1D) Na–O bridging chains. Four versatile coordination modes of carboxyl groups and Na–O coordination bi-chains linked by novel μ-O bridges (μ2-O and μ3-O) were demonstrated in the structure. Photoluminescence spectra of Eu-L were investigated to reveal characteristic emissions of Eu(III). This is the first example of hetero-bimetallic complex of the tetraazacrown ether ligand with lanthanide and sodium ions.     

Monometallic and bimetallic europium(III) and terbium(III) complexes: Synthesis and luminescent properties

Eight new lanthanide complexes of the form Ln(L)₃bipy and [Ln(L)₃]₂bpm were synthesized (where L = 2,2,6,6-tetramethyl-3,5-heptanedione (tmh) and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (tdh), bipy = 2,2′-bipyridine, bpm = 2,2′-bipyrimidine and Ln = Tb(III) or Eu(III)). The luminescent spectra are typical of Tb(III) and Eu(III) complexes with intense transitions at 545 nm for Tb(III) and 612 nm for the Eu(III) complexes. Energy gaps between the tmh 1 orbitals and the ⁰D_J manifold of Eu(III) are too large to give efficient energy transfer therefore emission spectra for Eu(tmh)₃bipy and [Eu(tmh)₃]₂bpm were not detected. Lifetimes are greatest for the Tb(III) complexes containing tmh terminal ligands while the longest lifetimes for the Eu(III) complexes occur with the tdh terminal ligands.     

3-D supramolecular frameworks assembled by lanthanide binuclear molecules based on 1,2-phenylenedioxydiacetic acid and 1,10-phenanthroline

The complexes [Ln₂(PDOA)₃(phen)₂(H₂O)₂] · 2H₂O (Ln = Eu (1), Tb (2), and Dy (3); H₂PDOA = 1,2-phenylenedioxydiacetic acid; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single crystal X-ray diffraction methods. The three complexes are all binuclear molecules. The two Ln(III) centers are linked by only one PDOA ligand through its two bidentate-chelating carboxylate groups. PDOA also acts as a terminal ligand using one carboxylate oxygen and ether oxygen atoms to chelate the Ln(III) ion. 3-D supramolecular frameworks are built up by the hydrogen bonds and π–π stacking interactions. The fluorescent spectra of the three complexes show the characteristic emission of the Eu(III) for 1, Tb(III) for 2, and Dy(III) for 3, respectively.     

Tuning the valence of 3,3-di(1H-tetrazol-5-yl)pentanedioic acid: Solvothermal synthesis of Eu(III) and bimetallic Eu(III)/Cu(II) compounds

3,3-Di(1H-tetrazol-5-yl)pentanedioic acid (H₄dtzpda) with four acidic hydrogen atoms can display different valence when reacted with different metal ions. Solvothermal reactions of H₄dtapda with Eu(NO₃)₃·6H₂O or Eu(NO₃)₃·6H₂O/Cu(NO₃)₂·6H₂O afford [Eu(Hdtzpda)(H₂O)₄]·4H₂O (1) and [Eu₂Cu(dtzpda)₂(H₂O)₁₀]·6H₂O (2), respectively, where only three acidic hydrogen atoms of H₄dtzpda are deprotonated in compound 1 while all the four acidic ones are deprotonated in compound 2. In compound 1, Hdtzpda^3 − acts as a pentadentate ligand to bridge Eu(III) centers via the oxygen atoms of the carboxylate group while in compound 2, dtzpda^4 − is a hepadentate one via not only the oxygen atoms of the carboxylate group but also the nitrogen atoms of the tetrazole rings. The luminescence properties of the two compounds in the solid state show both intraligand and characteristic peaks of Eu^3 + at room temperature.     

Spectroscopic and Thermal Studies of Mn(II), Fe(III), Cr(III) and Zn(II) Complexes Derived from the Ligand Resulted by the Reaction Between 4-Acetyl Pyridine and Thiosemicarbazide

Transition metal complexes of Mn(II), Fe(III), Cr(III) and Zn(II) metal ions with a general formulas [Mn(L)₂(Cl)₂]·4H₂O (I), [Fe(L)₂(Cl)₂]·Cl·6H₂O (II), [Cr(L)₂(Cl)₂]·Cl·6H₂O (III) and [Zn(L)₂(Cl)₂]·2H₂O (IV) where L = 4-acetylpyridine thiosemicarbazone, have been synthesized and interpreted using CHN elemental analysis, magnetic susceptibility measurements, molar conductance, thermal analysis and spectroscopic techniques; i.e., infrared, electronic UV/vis, ¹H-NMR and mass. The manganese(II), ferric(III), chromium(III) and zinc(II) complexes have octahedral geometry. The molar conductance measurements reveal that the Mn(II) and Zn(II) chelates are non-electrolytes but Fe(III) and Cr(III) have an electrolytic behavior. The IR spectra show that the 4-acetylpyridine thiosemicarbazone free ligand is coordinated to the metal(II) chlorides as a neutral bidentate ligand through both of the lone pair of electrons of the C=N azomethine group and C=S group. X-ray powder diffraction gives an impression that the resulting complexes are amorphous and different from the start materials. The thermogravimetric studies indicate that uncoordinated water molecules are lost in the first and second decomposition steps. The activation thermodynamic parameters E*, ΔH*, ΔS* and ΔG* are estimated from the differential thermogravimetric analysis (DTG) curves using Horowitz–Metzger (HM) and Coats–Redfern (CR) methods. The ligand and its complexes have been screened for antibacterial and antifungal activities against two bacteria; i.e., Escherichia coli (Gram −ve) and Bacillus subtilis (Gram +ve) and two fungi, i.e., tricoderma and penicillium activities).     

Four novel lanthanide(III) coordination polymers with 3D network structures containing 2-fold interpenetration

Four novel lanthanide(III) coordination polymers [Ln(L)_1.5(H₂O)₂]·5H₂O [Ln = Sm (1), Eu (2), Tb (3), Dy (4)] have been hydrothermally synthesized by the reaction of 1,2-bis[4-amino-5-carboxylmethylthio-(1,2,4-triazol-3-yl)]ethane (H₂L) with lanthanide(III) salts, and structurally characterized by single crystal X-ray diffraction. Polymers 1–4 are isostructural, in which all the Ln^III atoms are nine-coordinated and the carboxylate groups adopt three different coordination modes (bidentate chelate, bidentate bridging, bidentate chelate bridging) to connect Ln^III atoms. These polymers exhibit 3D network structures with 2-fold interpenetration, in which intriguing 1D channels are observed. Besides, the spectra properties of the title polymers are investigated, the strong luminescence characteristics of 2–3 are found.     

Construction of Two Lanthanide Complexes Involving In Situ 3,5-Dichlorosalicylate Synthesis

Hydrothermal reaction of 2,4-dichlorophenoxyacetic acid, 1,10-phenanthroline and Ln(NO₃)₃·6H₂O in the presence of a trace quantity of nitric acid produced two isostructural dinuclear complexes, Ln₂(2,4-dcp)₄(3,5-dcs)₂(phen)₂ (Ln = Tb (1); Tm (2), 2,4-dcp = 2,4-dichlorophenoxyacetate, 3,5-dcs = 3,5-dichlorosalicylate, phen = 1,10-phenanthroline), containing a new ligand, 3,5-dichlorosalicylate (3,5-dcs) that formed in situ. The lanthanide ions are bridged by two bidentate and two terdentate carboxylato groups to give centrosymmetric dimers with Ln···Ln separations of 3.935(2) and 3.917(3) Å, respectively. Each metal atom is nine-coordinate and exhibits a distorted, tricapped trigonal prismatic geometry. Three-dimensional fluorescence spectra show that both 1 and 2 emit the intense green characteristic luminescence at room temperature, with long lifetimes of up to 0.890 and 0.995 ms, respectively. Moreover, poor luminescence efficiency has been noted for complex 1.     

Frequently used,but still unknown: Terbium(III) tris-hexafluoroacetylacetonate dihydrate

This work provides direct access to the complex [Tb(hfa)₃(H₂O)₂] with elucidation of the molecular and crystal structure. It has been shown that the interaction of Tb(OAc)₃·4H₂O with H-hfa·2H₂O in water gives {[Tb₂(hfa)₄(F₃CCO₂)₂(H₂O)₄][Tb(hfa)₃(H₂O)₂]₂·H₂O}, which can be used as a source of pure [Tb(hfa)₃(H₂O)₂]. This compound is a good quantitative precursor for the synthesis of various Tb(hfa)₃ complexes due to its good solubility in common organic solvents such as hexane, benzene, ether and acetone. Hence, it opens new possibilities in the field of molecular magnetism and design for photonic and optoelectronic applications.     

CHARACTERIZATION OF THE LANTHANUM(III) AND EUROPIUM(III) TRICHLOROACETATE COMPLEXES EXTRACTED WITH 18-CROWN-6

ABSTRACT

Extraction of lanthanide(III) ions with 18-crown-6 (18C6) and trichloroacetate (tea) has been studied. The composition, hydration, and structure of the La(III) and Eu(III) complexes extracted into 1,2-dichloroethane were investigated by using several methods such as the liquid-liquid distribution technique, conductimetry, Karl Fisher titration, laser luminescence spectroscopy, and ¹H NMR. The La(III) complex was found to be a monohydrate, La(tca)₃(18C6)(H₂O), while that of Eu(III) was a mixture of a monohydrate and a dihydrate, i.e., Eu(tca)₃(18C6)(H₂0) and Eu(tca)₃(18C6)(H₂0)₂- The origin of the selectivity by 18C6 which gives much higher extractability of La(III) than of Eu(III) is explained by considering the hydration and probable structure of their complexes.     

Lanthanide(III) 1,4-Phenylenediacetate Complexes: The Relation Between the Structure and Thermal Properties

The series of isostructural lanthanide coordination polymers with the empirical formula [Ln₂(PDA)₃(H₂O)]·2H₂O, where PDA = 1,4-phenylenediacetate anion = [C₈H₈(COO)₂]^2?; Ln = La-Lu(III), and Y(III) were produced in the reaction of LnCl₃·nH₂O with ammonium salt of 1,4-phenylenediacetic acid in water solution. The compounds were characterised structurally using powder X-ray diffraction, elemental and thermogravimetric analyses as well as FT-IR spectroscopy. Thermogravimetric analyses show that in the range 60–170 °C the dehydration process occurs. The thermal stability of dehydrated compounds, Ln₂(PDA)₃ increased from about 200–350 °C in the whole series of complexes. Single-crystal X-ray diffraction analysis for the Gd(III) complex revealed that the compound crystallizes in the monoclinic P2₁/c space group with a = 21.863(2) Å, b = 10.035(1) Å, c = 13.854(1) Å, β = 91.53(1)° and V = 3,038.5(4) ų. The complex contains one-dimensional gadolinium-carboxylato chains, which are connected with the –CH₂–C₆H₄–CH₂– spacers of PDA ligand to the three-dimensional metal–organic framework.     

Subject Index to Volume 21

Abstract

Time‐resolved laser‐induced fluorescence spectroscopy (TRLFS) was employed to determine the inner‐sphere (i.e., first coordination sphere) hydration number (N _H2O) of lanthanide(III) ions (Ln = Sm, Eu, Tb, and Dy) in the TRPO‐dodecane/HNO₃ (or HNO₃–NaNO₃) system under various conditions. In addition, the N _H2O of Ln(III) in extracted complexes with octyl(phenyl)‐N,N‐diisobutylcarbamoylmethyl phosphine oxide (CMPO), dihexyl‐N,N‐diethylcarbamoylmethyl phosphonate (CMP), trioctyl phosphine oxide (TOPO), and tributyl phosphate (TBP) were also determined. The results show that there is no water molecule in the first coordination sphere of Ln(III) complexes, except for Sm(III) and Dy(III) in CMP complexes.     

Complexation of Eu(III) with Dibutyl Phosphate and Tributyl Phosphate

Abstract

The complexation of Ln(III) with tributyl phosphate (TBP) in the presence of dibutyl phosphate (HDBP) is of importance for the smooth operation of the plutonium uranium refining extraction (PUREX) process. The time resolved laser‐induced fluorescence spectroscopy (TRLFS) and extraction experiments were employed to study the complexation of Eu(III) with TBP or HDBP and their mixture. The emphasis was on the inner‐sphere hydration numbers and emission spectra of the Eu(III) extracted complexes. The results show that the HNO₃ loading in the organic phase influences not only the distribution ratio but also the emission spectra, as well as the hydration numbers of the complexes. For the Eu‐TBP complexes, one water molecule remained at low HNO₃ loading in the organic phase, and it would be removed at enhanced HNO₃ loading. For the Eu‐HDBP complexes, one water molecule remained at low or high HNO₃ loading. For the Eu‐HDBP/TBP or Eu‐HDBP/30%TBP, more than one species formed and third phase with different chemical form appeared at low HNO₃ loading. The possible species of Eu(III) complexes formed under various conditions were proposed and discussed.     

A New Series Lanthanide-2,6-Pyridinedicarboxylic Acid Complexes Containing Low Dimensionality: Synthesis,Structure and Photoluminescent Properties

Abstract  

Based on the 2,6-pyridinedicarboxylate acid ligand, ten lanthanide complexes with formula, (Hdipa)₃[Ln(L)₃] (Ln = Eu [1], Gd [2], Nd [3], Tb [4], Ce [5], Sm [6], Pr [7], Dy [8] and Er [9]) and [Nd(L)(HL)(H₂O)₂]·4H₂O (10), (where H₂L = 2,6-pyridinedicarboxylic acid and dipa = N-(1-methylethyl)-2-propanamine) have been prepared by different synthetic methods. Structural analyses reveal that complexes 1–3 are isomorphous, zero-dimensional structures, which are further connected to 3D H-bonding networks via extensive intermolecular hydrogen bonds. In the structures of these complexes, the dipa plays a key role in balancing electric charge. For complex 10, the 1D Ln–O–C–O–Ln polymeric chains are linked into a stable 3D H-bonding framework through numerous intermolecular and intramolecular hydrogen bonds. The luminescent properties of complexes 1, 4, 6 and 8 were investigated in detail.     

Extraction of Lanthanides(III) from HClO4 Solutions with Bis(diphenylphosphorylmethylcarbamoyl)alkanes

Abstract

Novel polyfunctional neutral organophosphorus compounds, namely bis(diphenylphosphoryl-methylcarbamoyl)alkanes of general formula [Ph₂P(O)CH₂C(O)NH]₂(CH₂)_n (I-III; n = 3, 5, 8), were synthesized and studied as extractants for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from perchloric acid solutions. The influence of both of HClO₄ concentration in the aqueous phase and that of the extractant in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. Bis(diphenylphosphorylmethylcarbamoyl)alkanes II and III possess a higher extraction efficiency towards Ln(III) than their monoanalogue Ph₂P(O)CH₂C(O)NHC₉H₁₉. The potentialities of polymeric resin impregnated with bis(diphenylphosphorylmethylcarbamoyl)pentane II for the preconcentration of lanthanides(III) from perchloric acid solutions are demonstrated.     

Polymeric [Eu(L)3(H2O)] (HL = 1-(pyridin-4-yl)butane-1,3-dione and Dimeric [Eu2(L)6(H2O)2] (HL = 1,3-di(pyridin-3-yl)propane-1,3-dione) as selective and sensitive chemosensors for Hg(II) ion

Eu(III) complexes, [Eu(L1)₃(H₂O)] (1) and [Eu₂(L2)₆(H₂O)₂] (2) have been prepared and structurally characterized. They are highly selective and sensitive chemosensors for Hg²⁺. These Eu-containing materials show fluorescent enhancement only for Hg²⁺. The complexation of other metal ions leads to fluorescence quenching or no response.     

A Series of Luminescent Lanthanide–Organic Complexes Constructed from In Situ Generated Dithiobenzoic Acid

Two types of lanthanide thiolato-carboxylate complexes, [Type I: [Yb(dtba) (Hdtba)] _n (1), Type II: [Ln(dtba)_1.5(biim)] _n (Ln = Pr (2a), Nd (2b), Sm (2c), Eu (2d), Gd (2e), Tb (2f), Dy (2g), H₂dtba = 2,2′-dithiodibenzoic acid, bimm = diimidazole)] have been obtained by hydrothermal method and characterized by the single-crystal X-ray diffraction, IR, 2D-COS IR, TG and the luminescence analysis. The H₂dtba ligand came from the in situ S–S function reaction of 2-mercaptobenzoic acid (H₂mba) under the hydrothermal condition. Complex 1 is a 2D bamboo-like sqr-topology layered structure, and the 3D (4, 4, 6)-connected supramolecular frameworks is produced by the hydrogen bonds of O–H···O. Complexes of type II (from 2a to 2g) are isostructural and they are assigned to 1D rope-like chains by introducing the chelating ligand of diimidazole. These 1D rope-like chains are further linked by N–H···O hydrogen bonds into a 3D supramolecular framework with CdSO₄-type topology. Photoluminescence studies reveal that complexes 2b, 2c, 2d, 2f, 2g exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.     

Structure and photophysical properties of new trinuclear lanthanide complexes (Ln = Eu and Tb) with 1,10-phenanthroline

Examples of trinuclear lanthanide (Ln) complexes using bridging sulfato and hydroxo ligands for Ln = Eu and Tb are reported. Structural data demonstrate that three nine-coordinate Ln³⁺ ions are caged in a monomeric structure in [Ln₃(phen)₃(OH)(SO₄)₄(DMF)₃] · DMF · H₂O, with Ln?Ln distances slightly greater than 4 Å. The luminescence and excitation spectra have been recorded and interpreted.     

Synthesis and electrochemistry of acetylacetonatolanthanide(III)- phthalocyaninates

The synthesis and electrochemistry of acetylacetonatolanthanide(III)phthalocyaninates are reported. Two new kinds of lanthanide complexes Li[Pc]Ln(acac)₂] and (Pc)Ln(acac) were obtained where Ln is the trivalent ions of Eu, Gd, Dy, Tb, Ho, Er, Tm, Lu, and Pc is the dianion of phthalocyanine and acac is the acetylacetonate anion. These complexes were characterized by infrared and electronic absorption spectroscopy. An overall oxidation reduction mechanism at a platinum electrode in dimethyl sulfoxide is presented.