Lanthanide Carboxylate Research Articles

Effect of the curing agent DETA and its interaction with a rare earth carboxylate as corrosion inhibitor in a hybrid silica-epoxy formulation

Sol–gel based coatings are used to protect metals from corrosion. They offer a barrier to the electrolyte penetration, but they do not provide active corrosion protection. Therefore, corrosion inhibitors are often added to sol–gel formulations to improve the overall corrosion behavior. Sol–gel-based coatings typically require relatively high temperatures to be properly cured, which supposes high energy consumptions and might damage some of the precursors of the formulation, including corrosion inhibitors incorporated to improve the coating’s properties. In this study, the effect of diethylenetriamine (DETA) as a curing agent, and yttrium 4-hydroxy cinnamate [Y-(4OHCin)3] as corrosion inhibitor, on the chemistry and corrosion performance of a hybrid silica-epoxy formulation are investigated. Solid nuclear magnetic resonance and attenuated total reflectance Fourier transform infrared spectroscopy are carried out to analyze the influence of the curing agent and the corrosion inhibitor on the chemical structure of the coating. The corrosion performance is assessed by means of electrochemical impedance spectroscopy, and the results are evaluated considering the chemical study and the interaction between the different compounds.

Lanthanum and some lanthanides 2,4-dichlorophenoxyactetates: Structure and luminescent properties

The exchange interaction of lanthanum and some lanthanides salts (neodymium, samarium, europium, gadolinium, terbium and dysprosium) with sodium salt of 2,4-dichlorophenoxyacetic acid (HL) in dimethylformamide medium produced lanthanum and lanthanide carboxylates. The compounds were studied by elemental and thermal analysis, infrared spectroscopy and X-ray structure analysis. It was found that the complexes form two isostructural series: [Ln2L6(DMF)3]∙Solv (Ln = La, Nd, Sm, Eu) and [LnL3(H2O)2]∙2DMF∙Solv (Ln = Gd, Tb, Dy). Both series have a one-dimensional polymer structure in which the central atoms are connected by bridging carboxylate anions. The crystal structures of the complexes have a branched network of noncovalent D-H…A and Cl…Cl interactions. An analysis of the photophysical properties of all compounds revealed a bright luminescence with a quantum yield up to 39.5 % and an excited state lifetime of 1330 μs for the europium polymer enhanced by 2,4-dichlorophenoxyacetate ligands.

Dual function of rare earth carboxylate compounds on the barrier properties and active corrosion inhibition of epoxy coatings on mild steel

In this work, two rare earth carboxylate compounds, lanthanum 4-hydroxycinnamate (La(4-OHcin)3) and yttrium 3-(4-methylbenzoyl)propanoate (Y(mbp)3), were incorporated into bisphenol-based epoxy resin to investigate their effectiveness in coating barrier properties and active corrosion inhibition. EIS results showed that the incorporation of rare earth carboxylate inhibitors significantly improved corrosion resistance compared to the inhibitor free coating, with the global impedance modulus remaining at a level higher than 1 GΩ cm2 after 219 days immersion. Following EIS experiments, cross-sectional views of the coatings exhibited a pore-plugging behavior by rare earth containing precipitates, which reinforced the coating barrier properties and delayed the electrolyte diffusion process. These effects were also reflected from the electrochemical parameters extracted from breakpoint frequency analysis and equivalent circuit modelling. Filiform corrosion experiments for artificially scratched coatings suggest that the addition of rare earth carboxylates effectively suppressed the initiation and growth of filaments as well as the development of the coating delamination front. The active corrosion inhibition is possibly related to the formation of a surface protective film consisting of bimetallic complexes and rare earth metal rich precipitates. The electrochemical measurements and surface analyses evidence the dual function of rare earth carboxylate species for enhancing coating barrier properties against electrolyte penetration and providing active corrosion inhibition for the underlying AS1020 mild steel.

Diverse Coordination Chemistry of the Whole Series Rare-Earth L-Lactates: Synthetic Features, Crystal Structure, and Application in Chemical Solution Deposition of Ln2O3 Thin Films.

Rare-earth (RE, Ln) carboxylates are widely studied as precursors of RE oxide-based nanomaterials; however, no systematic studies of RE L-lactates (HLact = 2-hydroxypropanoic acid) have been reported to date. In the present work, a profound structural investigation of RE L-lactates is carried out. A family of RE lactate complexes of the general formula LnLact3∙nH2O (Ln = La, Ce-Nd, Sm-Lu, Y; n = 2-3) are synthesized and characterized by CHN, TGA, and FTIR as well as by powder and single-crystal XRD methods.The existence of four novel structural types (1-Ln-4-Ln) is revealed. Compounds of the 1-Ln type (Ln = La, Ce, Pr) exhibit a chain polymeric structure, whereas 2-Ln-4-Ln compounds are molecular crystals consisting of dimeric (2-Ln; Ln = La, Ce-Nd) or monomeric (3-Ln-Ln = Sm-Lu, Y; 4-Ln-Ln = Sm-Gd, Y) species. The crystal structures of 1-Ln-4-Ln compounds are discussed in terms of their coordination geometry and supramolecular arrangement. Solutions of yttrium and lanthanum lactates with diethylenetriamine are applied for the chemical deposition of Y2O3 and La2O3 thin films.

Syntheses, Structures, and Corrosion Inhibition of Various Alkali Metal Carboxylate Complexes.

Complexes of the alkali metals Li-Cs with 3-thiophenecarboxylate (3tpc), 2-methyl-3-furoate (2m3fur), 3-furoate (3fur), 4-hydroxycinnamate (4hocin), and 4-hydroxybenzoate (4hob) ions were prepared via neutralisation reactions, and the structures of [Li2(3tpc)2]n (1Li); [K2(3tpc)2]n (1K); [Rb(3tpc)(H2O)]n (1Rb); [Cs{H(3tpc)2}]n (1Cs); [Li2(2m3fur)2(H2O)3] (2Li); [K2(2m3fur)2(H2O)]n (2K); [Li(3fur)]n(3Li); [K(4hocin](H2O)3]n (4K); [Rb{H(4hocin)2}]n.nH2O (4Rb); [Cs(4hocin)(H2O)]n (4Cs); [Li(4hob)]n (5Li); [K(4hob)(H2O)3]n (5K); [Rb(4hob)(H2O)]n (5Rb); and [Cs(4hob)(H2O)]n (5Cs) were determined via X-ray crystallography. Bulk products were also characterised via XPD, IR, and TGA measurements. No sodium derivatives could be obtained as crystallographically suitable single crystals. All were obtained as coordination polymers with a wide variety of carboxylate-binding modes, except for dinuclear 2Li. Under conditions that normally gave coordinated carboxylate ions, the ligation of hydrogen dicarboxylate ions was observed in 1Cs and 4Rb, with short H-bonds and short O…O distances associated with the acidic hydrogen. The alkali-metal carboxylates showed corrosion inhibitor properties inferior to those of the corresponding rare-earth carboxylates.

Synthesis, Characterization, and Antibacterial Properties of mixed ligand Complexes of (L-leucine and 8-hydroxyquinoline) with Fe (III ),Cr (III) La(III)) and Ru(III ) ions

The research includes the synthesis and identification of the mixed ligands complexes of M+3 Ions in general composition ,[M(Leu)2(Q)]
 Where L-leucin (C6H13NO2)symbolized as( Leu H) as a primary ligand and
 8-hydroxyqinoline,(C9H7NO) symbolized as (8-HQ) as a secondary ligand .
 The ligands and the metal chlorides were brought in to reaction at room temperature in ethanol as solvent. The reaction required the following molar ratio [(1:1:2)(metal): Q-:2Leu-] with M(III ) ions, were 
 M(III) = Fe (III ),Cr (III) La(III)) and Ru(III )
 The reaction gave solid crystalline complexes which have been characterized us the following techniques: Thermal stability, Solubility, Molar conductivity, Determination the percentage of the metal in the complexes by (AAS). Spectroscopic Methods [FT-IR and UV-Vis], and. The proposed structure of the complexes using program, chem. office 3D(2006) .], Biological effects for some complexes were investigated .
 Numerous papers have been published on metal complexation of amino acids and derivatives during the past ten years. Metal amino acid complexes have long been of interest as models for metal –Ligand systems and interaction which may occur in nature(1)Biological importance of several amino acids their complexes with transition metals is well documented(2-3)The amino acid L- leucin and various transition metals are important in the biological functions of humans, animals, and plants. L- leucine is one of the twenty major amino acids and is considered an essential amino acid (4)
 8-hydroxyqinoline or 8-qinolineis an organic compound with the formula C9H7NO2 is the name most commonly used ,while its trivial name is (oxine),which is conventionally used for the description of chelate compounds Oxinates ,as out of seven possible hydroxyqinoles, only 8-hydroxyqinoline forms chelate with metal ions . [5-6]
 Ruthenium polypyridyl and phenanthroline complexes have been extensively investigated because of their interesting photochemical[7],catalytic [8], biological [9] and electrochemical [10,11] properties.
 Lanthanide(III) carboxylates have been widely studied in recent years due to their physico-chemical properties, variety of structural types and potential uses as fluorescent sensors. The isomers of mono-,di- and trimethoxybenzoates of rare earth elements(III) have been examined. [12-13]
 A series of ruthenium metal complexes involving mono-sulfonylated non-innocent o-phenylenediamine ligands have been characterized in detail using NMR, MS, FT-IR, X-Ray, UV-vis and electrochemical studies. [14]
 In this paper we present the synthesis and study of Cr(III),Fe(III) La(III) and Ru(III) complexes with amino acid (L-leucin) as a primary ligand and 8-hydroxyqinoline as a secondary ligand have been used, respectively.

RE(III) 3-Furoate Complexes: Synthesis, Structure, and Corrosion Inhibiting Properties.

In this study, two types of Rare Earth (RE) 3-furoate complexes were synthesized by metathesis reactions between RE chlorides or nitrates and preformed sodium 3-furoate. Two different structural motifs were identified as Type 1RE and Type 2RE. The Type 1RE monometallic complexes form 2D polymeric networks with the composition [RE(3fur)3(H2O)2]n (1RE = 1La, 1Ce, 1Pr, 1Nd, 1Gd, 1Dy, 1Ho, 1Y; 3furH = 3-furoic acid) while Type 2RE bimetallic complexes form 3D polymeric systems [NaRE(3fur)4]n (2RE = 2Ho, 2Y, 2Er, 2Yb, 2Lu). The stoichiometric mole ratio used (RE: Na(3fur) = 1:3 or 1:4) in the metathesis reaction determines whether 1RE or 2RE (RE = Ho or Y) is formed, but 2RE (RE = Er, Yb, Lu) were obtained regardless of the ratio. The corrosion inhibition behaviour of the compounds has been examined using immersion studies and electrochemical measurements on AS1020 mild steel surfaces by a 0.01 M NaCl medium. Immersion test results revealed that [Y(3fur)3(H2O)2]n has the highest corrosion inhibition capability with 90% resistance after 168 h of immersion. Potentiodynamic polarisation (PP) measurements also indicate the dominant behaviour of the 1Y compound, and the PP curves show that these rare earth carboxylate compounds act predominantly as anodic inhibitors.

Blue-Emitting Ligand-Mediated Assembly of Rare-Earth MOFs toward White-Light Emission, Sensing, Magnetic, and Catalytic Studies.

New lanthanide carboxylate compounds with two- (2D) and three-dimensional (3D) structures have been prepared by employing 2,5-bis(prop-2-yn-1-yloxy)terephthalic acid (2,5-BPTA) as an organic linker. The compounds, [Ln(C14H8O6)(C7O3H4)·2H2O]·4(H2O), Ln = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy and [Ln(C7O3H4)3·(C3H7ON)·(H2O)]·2(H2O)(C3H7NO), Ln = La, Ce, Pr, have two- and three-dimensional structures, respectively. In all compounds, lanthanide ions are connected together, forming a dimer, which is connected by the 2,5-BPTA ligand. In the two-dimensional structure, there are two 2,5-BPTA moieties present, and in the three-dimensional structure, there are three 2,5-BPTA moieties present. The lanthanide centers are nine-coordinated, the 2D structure has a tricapped trigonal prismatic arrangement, and the 3D structure has a monocapped distorted square antiprismatic arrangement. The Pr compound forms in both 2D and 3D structures, whose formation depends on the time of the reaction (2 days─2D and 5-6 days─3D). The ligand emits in the blue region, and using the characteristic emission of Eu3+ (red) and Tb3+ (green) ions, we achieve white light emission in the (Y0.96Tb0.02Eu0.02) compound. The overall quantum yield for the white light emission is 28%. The strong green luminescence of the Tb3+-containing compound was employed to selectively sense the Cr3+ and Fe3+ ions in aqueous solution with limits of detection (LODs) at 0.41 and 8.6 ppm, respectively. The Tb compound was found to be a good heterogeneous catalyst for the Ullman-type O-arylation reaction between phenol and bromoarene with yields of 95%. Magnetic studies on the Gd-, Tb-, and Dy-containing compounds showed weak exchange interactions within the dimeric Ln2 units. The present work demonstrates the many utilities of the rare-earth-containing MOFs, especially toward white-light emission, metal-ion sensing, and heterogeneous catalysis.

Thermal, Spectroscopy and Luminescent Characterization of Hybrid PMMA/Lanthanide Complex Materials.

Novel hybrid materials based on the poly(methyl methacrylate) (PMMA) matrix and lanthanide(III) carboxylates Eu:2,6-DClB and Tb:2,6-DClB were synthesized and carefully analyzed in the context of their potential application in optically active polymer-based optical fibers. To determine the usefulness of the obtained materials, a careful thermal, mass spectroscopy, and optical characterization was performed, focusing on the features critical for the technology of optical fiber processing. In addition, the luminescent features of both lanthanide complexes and the resulting hybrid composites were carefully investigated to identify the processes responsible for light emission and to analyze the influence of the PMMA host on light emission intensity and spectral characteristics. The obtained results showed that both lanthanide carboxylate complexes exhibited intense luminescence in the red and green spectral range, typical of europium and terbium dopants, and that those features were well preserved after introducing them into the PMMA polymer. Thermal analysis also proved that introducing the luminescent additives did not significantly affect the thermal properties of both hybrid materials, thus enabling further processing into the form of optical fibers.

Synthesis, structure, and corrosion inhibiting properties of phenylacetato-rare earth(III) complexes

A series of phenylacetato (PhAc) rare earth complexes with aqua and 2,2′-bipyridine (bpy) co-ligands have been synthesized by metathesis reactions in water. Structures of the aqua complexes [RE(PhAc)3(H2O)] n (RE = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho), {[Lu4(PhAc)12(H2O)2]·1.5H2O} n and the bpy derivatives [RE(PhAc)3(bpy)]2 (RE = Y, Nd, Eu, Er) and {[La(PhAc)3(H2O)] . ½bpy} n have been determined. Powder XRD determined all aqua complexes except RE = Er, Yb, Lu are isotypic linear polymers, with nine coordinate tricapped trigonal prismatic geometry. The lutetium complex is also a linear polymer, but with distinct metal centers, three eight coordinate, and one nine. Except for RE = La and Ce, the bpy analogues are isostructural symmetrical dimers, with nonacoordinate metal centers. The lanthanum complex is a nonacoordinate linear polymer with coordinated water and lattice bpy. Their corrosion inhibitory properties on mild steel, showed the highest efficiency for [Nd(PhAc)3(H2O)] n (55%). The lanthanum species with solvated 2,2′-bipyridine proved a more effective corrosion inhibitor than the aqua version. Where both the aqua and bpy complexes were tested, the former performed better than the latter. These results provide insight into the effect of structure on the corrosion inhibiting properties of rare earth carboxylates.

Structural variability of rare earth carboxylates based on polydentate carboxylate ligand containing pyridine group

Four rare earth carboxylates, namely [Y(L) (DMF) (H2O)]·H2O (1), Y(L) (H2O) (2), La(L) (DMF) (3) and La(L) (H2O) (4), have been hydro/solvothermally synthesized from 2-(6-carboxypyridin-2-yl)terephthalic acid (H3L) and systematically characterized using IR, EA, single-crystal and powder X-ray diffraction, luminescence methods. The structural characterizations reveal that the crystal structures of rare earth carboxylates can be effectively altered by judicious alteration of the synthesis conditions. These complexes are very stable and display intense intraligand emissions.

Lanthanide 5,7-Disulfonate-1,4-naphthalenedicarboxylate Frameworks Constructed from Trinuclear and Tetranuclear Lanthanide Carboxylate Clusters: Proton Conduction and Selective Fluorescent Sensing of Fe3.

The novel sulfonate-carboxylate ligand of 5,7-disulfonate-1,4-naphthalenedicarboxylic acid (H4-DSNPDC) was synthesized, and its series of lanthanide compounds {[Ln3(μ2-OH)(DSNPDC)2(H2O)x]·yH2O}n (JXNU-7; Ln = La3+, x = 10. y = 4; Ln = Nd3+, Sm3+ Eu3+, x = 9, y = 2) and {[Ln4(μ3-OH)4(DSNPDC)2(H2O)11]·28H2O}n (JXNU-8; Ln = Eu3+, Gd3+) are presented. JXNU-7 is a three-dimensional structure based on linear trinuclear Ln3 building units, while JXNU-8 has a two-dimensional layer constructed from tetranuclear Ln4(μ3-OH)4 building units. The representative Eu compounds of JXNU-7 and -8 show good proton conductive properties under high humidity. The hydrophilic sulfonate groups pointing to the pores and the water molecules included in the pores mainly contribute to the high proton conductivity for the materials. The presence of one-dimensional infinite hydrogen-bonded networks in channels of JXNU-7(Eu) facilitates a fast and efficient proton transfer, resulting in higher proton conductivity in comparison to that of JXNU-8(Eu). Additionally, JXNU-7(Eu) with a characteristic red emission exhibits a promising potential for selective sensing of Fe3+ ions in aqueous solution. Our work demonstrates the integration of functional organic components (sulfonate groups) and inorganic components (lanthanide centers) in MOFs for the successful preparation of multifunctional MOF materials.

Leaching Behavior and Corrosion Inhibition of a Rare Earth Carboxylate Incorporated Epoxy Coating System.

While paint coatings act as important barriers to corrosion, defects can lead to localized, rapid metal loss. The addition of corrosion inhibitors that are capable of leaching from a coating to protect the metal surface at a defect can prevent this type of corrosion. This work investigates the release and corrosion protection capabilities of two rare earth (RE) carboxylate inhibitors from an epoxy coating as an initial step to understanding their leaching behavior and interaction with the coating system. Leaching experiments were performed via inductively coupled plasma mass spectroscopy (ICP-MS) analyses of the solutions in which free-standing coatings loaded with varying concentrations of inhibitor compounds had been immersed. Inhibitor release from the epoxy coating was observed to be dependent on initial inhibitor concentration, inhibitor chemistry, and solution pH conditions. The coating systems with greater initial inhibitor loadings showed higher leaching rates, particularly in acidic environments. Following immersion, the absence of characteristic inhibitor peaks in the FTIR spectra of the coatings also confirmed leaching had taken place. Cross-sectional views of the coatings after exposure to the pH 1 environment presented a chloride infusion zone at the coating/solution interface where the inhibitor had leached out. The RE active inhibition provided by the leached RE carboxylate inhibitors was verified by exposure of a coating defect to a chloride contaminated environment.

Self‐Assembly of Hexanuclear Lanthanide Carboxylate Clusters of Three Architectures

Synthesis of new lanthanide‐based poly‐hydroxo clusters is a key challenge in the deliberate design of novel metal‐organic frameworks with functional properties. Most of the current approaches fail to isolate stable hexanuclear entities to be used as pre‐existing building blocks for such frameworks. Herein we highlight the new two‐step synthetic route for the new family of hexanuclear lanthanide hydroxo pivalate compounds: self‐controlled hydrolysis and subsequent introduction of amine ligand. Three different octahedral architectures stabilized by intermolecular hydrophobic interactions and intramolecular H‐bonds have been found within the system of lanthanide pivalate and diethylenetriamine, and supramolecular organization of the compounds was examined. This is the first demonstration of isolation of hollow and O‐centered LnIII6(OH)8 cluster from the same system.

Synthesis and thermal decomposition of rare earth isovalerates and their solutions with amines as an effective pathway to obtain oxide nanomaterials

Rare earth (RE) carboxylates are considered as effective metal-organic precursors (MOPs) for chemical preparation of RE oxide nanomaterials via thermal decomposition. However RE oxocarbonates being the intermediate products of this process require high temperature treatment to be decomposed, that complicates the application of mentioned MOPs for preparation of nanomaterials. Here we report synthesis, composition and thermal behavior of four rare earth (La, Gd, Y, Lu) isovalerates. Novel compounds were studied by single crystal and powder XRD, TG-DTA, FTIR and DFT calculations. Thermal decomposition of RE isovalerates and metal-organic precursors based on the RE isovalerate – isopropanol – amine (monoethanolamine or diethylenetriamine) systems was thoroughly studied. The effect of amines, decomposition atmosphere (air or argon) and nature of RE ion on thermal behavior was discussed. The developed MOPs decompose to RE oxides below 700 °C which allows them to be used for deposition of high-quality Y2O3 and LaLuO3 thin films by MOCSD process.

A facile route for tuning emission and magnetic properties by controlling lanthanide ions in coordination polymers incorporating mixed aromatic carboxylate ligands

A series of lanthanide coordination polymers, [Ln (Btca) (Pimda)·2H2O]n (Ln = Nd(1), Sm(2), Eu(3), Gd(4), Tb(5), Dy(6)), (HBtca = 1H-benzo[d][1, 2, 3]triazole-5-carboxylic acid and H3Pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) have been obtained through moderate temperature hydrothermal syntheses. Single crystal X-ray analyses reveal the family of polymers exhibit same 1D chains composed by binuclear units, and further being extended into 2D layer connected by H3Pimda. The 2D layers are further interlinked by strong intermolecular hydrogen bonds interactions, resulting in the 3D supramolecular architectures. The solid state of 4 shows ligand based fluorescence, while 1, 2, 3, 5 and 6 exhibit strong/moderate photoluminescence emissions in the NIR/visible regions based on characteristic Ln3+ emission selected. Importantly, by in situ doping different concentrations of Eu3+ and Tb3+ cations, series of Eu3+/Tb3+ binary polymers were fabricated, showing a tunable emission color from green, yellow, orange to red. Moreover, the magnetic studies reveal the presence of very weak ferromagnetic Gd···Gd coupling within the binuclear units of 4. The depopulation of Stark components at low temperature and possible weak anti-ferromagnetic interactions were observed within polymers 2 and 5. Remarkably, ac magnetic susceptibility study reveals the Dy3+ polymer is a candidate for elucidation of slow relaxation of the magnetization in lanthanide carboxylate system.

New, environmentally friendly, rare earth carboxylate corrosion inhibitors for mild steel

Four recently synthesized rare earth 3-(4-methylbenzoyl)propanoate (mbp) compounds (RE = La, Ce, Nd and Y) were evaluated as corrosion inhibitors for mild steel in 0.01 M NaCl. At a concentration of 0.25 mM all the compounds showed some level of inhibition after 30 min immersion, with the Y(mbp)3 complex giving the largest reduction in corrosion current density, from 1.92 μA/cm2 for the control sample to 0.25 μA/cm2 for the Y based inhibitor. All the RE(mbp)3 inhibitors acted predominantly as anodic inhibitors, showing little effect on the cathodic reaction after 30 min. Surface analysis after 6 h immersion using FTIR and EDS detected the presence of a thin film containing inhibitor components on all surfaces, thus accounting for the reduced corrosion rate, with the Y(mbp)3 compound having the most significant effect on corrosion and showing the most uniform surface coverage.

Crystal structure of poly[[di-μ3-acetato-tetra-aqua-bis-(μ2-cyclo-hexane-1,4-di-carboxyl-ato)dilanth-an-um(III)] dihydrate

The title compound, {[La2(CH3COO)2(C8H10O4)2(H2O)4]·2H2O} n or [La2(ac)2(e,a-cis-1,4-chdc)2(H2O)4]·2H2O, where ac is acetate and 1,4-chdc is cyclo-hexane-1,4-di-carboxyl-ate anion, is a binuclear lanthanum(III) complex. Each metal atom is deca-coordinated by four O atoms from two distinct 1,4-chdc2- ligands, four O atoms from three acetate groups and two O atoms from coordinated water mol-ecules to form a distorted bicapped square-anti-prismatic geometry. Two non-coordinated water mol-ecules are also present in the formula unit. The most remarkable feature of this compound is that it possesses a only cis conformation for cyclo-hexane-1,4-di-carb-oxy-lic acid, although the raw material consists of a mixture of cis and trans isomers. The μ3-η2:η2 coordination mode of the bridging acetate group and the flexible di-carboxyl-ate fragments of 1,4-chdc2- results in the formation of infinite two-dimensional lanthanide-carboxyl-ate layers within the crystal structure. The directionality of strong inter-molecular O-H⋯O and weak C-H⋯O inter-actions provides robustness to the layers, which leads to the construction of a three-dimensional supra-molecular network. The crystal studied was refined as a two-component twin.

Self-assembly of heteroleptic tetranuclear carboxylate complexes of yttrium and lanthanides during hydrolysis and oxidation of rare earth homoleptic carboxylates

Novel heteroleptic carboxylate complexes bearing hydroxide or peroxide ligands were obtained by hydrolysis [Y4(Ph2CHCOO)10(OH)2(THF)2] (1) or oxidation [Ln4(Ph3CCOO)8(O2)2(THF)4(H2O)2] Ln=Nd (4), Eu (5), and [Nd4(Ph3CCOO)8(O2)(O)(THF)4] (4a). Crystal structure of 1, 4, 4a and 5 were determined by single-crystal X-ray diffraction. The molecular structures of all complexes obtained demonstrate planar framework consisting of four lanthanide or yttrium cations. In the 4a, the rather rare μ3-κ1:κ1:κ1 type of coordination of peroxide for lanthanide complexes was found. Synthesis of these compounds shows the possibility of self-association of rare earth carboxylates under the action of moisture and oxygen.

Syntheses, structures, and luminescence of three new lanthanide carboxylate complexes

ABSTRACTThe syntheses, luminescence and structures of {[Ln(L)3(2,2′-bipy)]n·H2O} (Ln = Y(1), Yb(2), and Er(3)) (3-(2-hydroxyphenyl)propanoic acid (HL)), determined by single-crystal X-ray diffraction, are reported.The structural determinations indicated that compounds 1–3 have similar dimer with six carboxylate bridges; the adjacent dimer can be further linked into two-dimensional (2D) sheets via the hydrogen (H) bond interactions. Furthermore, the luminescent properties of compound 2 showed the mild emissive feature.