Bidentate Carboxylate Groups Research Articles

Crystal structure and thermally enhanced photoluminescence in Eu(III) coordination polymers self-assembled from p-nitrobenzoic acid

Luminescent thermal quenching is a very troublesome thing for the practical application of luminescent materials, but also is a very common phenomenon. In theory, artificially reducing the number of quenching group around the luminescent lanthanide ion can effectively enhance the luminescence of lanthanide luminescent materials. In this paper, {[Eu2(NBA)6(H2O)4]∙H2O}n [Eu-NBA, NBA = p-nitrobenzoic acid] coordination polymers containing abundant coordination and interstitial water molecules were synthesized via hydrothermal methods. The chemical composition, crystal structures, and thermal stability of Eu-NBA coordination polymers were systemically investigated by Frontier-transfer infrared (FTIR) spectra, single-crystal X-ray diffraction and thermogravimetric analysis. X-ray diffraction analysis results revealed that Eu-NBA coordination polymers were crystallized into one-dimensional (1D) chain structures, where the adjacent Eu3+ ions were linked together by bidentate and/or tetradentate bridging carboxylate groups of the NBA ligands. The temperature-dependent photoluminescence spectra revealed that the shape and intensity of the luminescence spectra strongly depended on the coordination environment around Eu3+, and significant luminescent thermal enhancement was observed. These experimental results provided useful theoretical support for further understanding of the luminescence enhancement mechanism of lanthanide coordination polymers.

Synthesis, Spectral Characterization and Potential Fluorescent Properties of Three Lanthanide(III) Ions Complexes with Nalidixic Acid.

Three new solid lanthanide complexes with nalidixic acid (HNal) with the stoichiometry [Ln(Nal)3]·5·.5H2O (Ln=Tb, Dy and Ho) were synthesized applying the green synthesis method from the aqueous solutions without the organic solvent addition and fully characterized by the elemental analysis, XRF, complexometric titration, gravimetric analysis, molar conductivity and solubility measurements, powder X-Ray diffraction, UV-Vis and infrared (FT-IR) spectroscopies. Moreover, the luminescent properties of the Tb(III), Dy(III), and Ho(III) complexes in the solid state and in the solutions were investigated. On the basis of the detailed spectral analysis, it was concluded that the nalidixate ligands bind to the lanthanide ions by the bidentate carboxylate and carbonyl groups while water molecules belong to the outer coordination sphere. At the excitation of UV light, the complexes exhibited characteristic emission of central lanthanide ions, the intensity of which depends significantly on the excitation wavelength and/or the solvent. Thus, the application of nalidixic acid (apart from biological activity) for the synthesis of luminescent lanthanide complexes was confirmed which can find potential applications in the field of photonic devices and/or bioimaging agents.

Optimized Coordination of Uranyl in Engineered Calmodulin Site 1 Provides a Subnanomolar Affinity for Uranyl and a Strong Uranyl versus Calcium Selectivity.

As an alpha emitter and chemical toxicant, uranium toxicity in living organisms is driven by its molecular interactions. It is therefore essential to identify main determinants of uranium affinity for proteins. Others and we showed that introducing a phosphoryl group in the coordination sphere of uranyl confers a strong affinity of proteins for uranyl. In this work, using calmodulin site 1 as a template, we modulate the structural organization of a metal-binding loop comprising carboxylate and/or carbonyl ligands and reach affinities for uranyl comparable to that provided by introducing a strong phosphoryl ligand. Shortening the metal binding loop of calmodulin site 1 from 12 to 10 amino acids in CaMΔ increases the uranyl-binding affinity by about 2 orders of magnitude to log KpH7 = 9.55 ± 0.11 (KdpH7 = 280 ± 60 pM). Structural analysis by FTIR, XAS, and molecular dynamics simulations suggests an optimized coordination of the CaMΔ-uranyl complex involving bidentate and monodentate carboxylate groups in the uranyl equatorial plane. The main role of this coordination sphere in reaching subnanomolar dissociation constants for uranyl is supported by similar uranyl affinities obtained in a cyclic peptide reproducing CaMΔ binding loop. In addition, CaMΔ presents a uranyl/calcium selectivity of 107 that is even higher in the cyclic peptide.

Discovery and characterization of UipA, a uranium- and iron-binding PepSY protein involved in uranium tolerance by soil bacteria.

Uranium is a naturally occurring radionuclide. Its redistribution, primarily due to human activities, can have adverse effects on human and non-human biota, which poses environmental concerns. The molecular mechanisms of uranium tolerance and the cellular response induced by uranium exposure in bacteria are not yet fully understood. Here, we carried out a comparative analysis of four actinobacterial strains isolated from metal and radionuclide-rich soils that display contrasted uranium tolerance phenotypes. Comparative proteogenomics showed that uranyl exposure affects 39-47% of the total proteins, with an impact on phosphate and iron metabolisms and membrane proteins. This approach highlighted a protein of unknown function, named UipA, that is specific to the uranium-tolerant strains and that had the highest positive fold-change upon uranium exposure. UipA is a single-pass transmembrane protein and its large C-terminal soluble domain displayed a specific, nanomolar binding affinity for UO22+ and Fe3+. ATR-FTIR and XAS-spectroscopy showed that mono and bidentate carboxylate groups of the protein coordinated both metals. The crystal structure of UipA, solved in its apo state and bound to uranium, revealed a tandem of PepSY domains in a swapped dimer, with a negatively charged face where uranium is bound through a set of conserved residues. This work reveals the importance of UipA and its PepSY domains in metal binding and radionuclide tolerance.

Thermal study, temperature diffraction patterns and evolved gas analysis during pyrolysis and oxidative decomposition of novel ternary complexes of light lanthanides with mefenamic acid and 1,10-phenanthroline

New ternary lanthanide complexes with mefenamic acid (Hmef) and phenanthroline with the stoichiometry Ln2(mef)5(phen)(OH)·nH2O (Ln = La and Ce) and Ln2(mef)4(phen)(OH)2·nH2O (Ln = Pr, Nd, Sm, Eu and Gd) were synthesized and fully characterized by an elemental analysis, infrared spectroscopy, powder X-Ray diffraction (PXRD), combined thermogravimetry and differential scanning calorimetry (TG-DSC) in air and nitrogen atmospheres, evolved gas analysis by combined TG-FTIR-MS techniques as well as temperature controlled X-ray diffraction.The PXRD data suggest that the compounds are crystalline or amorphous and no isomorphic series were obtained. The FTIR spectra suggested the coordination of the lanthanide ions by the bidentate carboxylate groups of mefenamates as well as nitrogen atoms of phenanthroline.The thermal decomposition pathways of the complexes depended on the metal center and differed in air atmosphere and nitrogen atmosphere. From the temperature diffraction patterns, it was experimentally confirmed that in-air degradation of the complexes proceeded with the formation of various lanthanide oxycarbonates as intermediate solids and the decomposition was completed up to 1000 °C with the formation of the appropriate lanthanide oxides as a final solid product. It was proved that during degradation of the tested compounds in nitrogen atmosphere, a mixture of lanthanide oxide, lanthanide oxycarbonate, and soot is formed as an intermediate solid product at around 800 °C and pyrolysis is not finished for all compounds up to 1000 °C. The main gaseous products released during the thermal decomposition of these compounds were water vapor, carbon dioxide, carbon monoxide, nitrogen oxide and ammonia (in air atmosphere), as well as water vapor, carbon oxides, ammonia and a mixture of hydrocarbons from mefenamate ligand degradation (in nitrogen atmosphere).

Crystal structures and spectroscopic properties of copper(II)–dipicolinate complexes with benzimidazole ligands

The syntheses, crystal structures and spectroscopic properties of three Cu(II)–dipicolinate complexes with benzimidazole ligands, namely [Cu(bzim)(dipic)(MeOH)] (1), [Cu2(2-Etbzim)2(dipic)2]n·0.5nH2O (2) and [Cu2(2-iPrbzim)2(dipic)2]n (3), where dipic = dipicolinate, bzim = 1-H-benzimidazole, 2-Etbzim = 2-ethyl-1-H-benzimidazole and 2-iPrbzim = 2-isopropyl-1-H-benzimidazole, are reported. Crystal structure studies revealed different coordination modes of the dipicolinate ligands; tridentate chelating for monomeric complex 1, and both tridentate chelating and bridging for similar polymeric complexes 2 and 3. Polymers 2 and 3 both contain two units, in which the Cu(II) central atoms Cu1 and Cu2 have different coordination polyhedra. The first unit {Cu(dipic)2} with Cu1 is connected to the second via two bidentate carboxylate groups of an μ3-bridging dipicolinate. In the second unit, Cu2 is coordinated by two imidazole nitrogen atoms from 2-ethyl-1-H-benzimidazole (2) or 2-isopropyl-1-H-benzimidazole (3) ligands. Complex 2 is of higher symmetry and has a localized Cu(II) atom Cu2 in a special position on the twofold axis. EPR spectra of all three Cu(II) complexes, which were measured at both room temperature and 98 K, indicate distorted tetragonal coordination spheres for all the Cu(II) atoms. The g-factor relation (g//> g┴ > 2.0023) is consistent with a $$d_{{x^{2} - y^{2} }}$$ ground electronic state in each case.

Molecular Assemblies of a Series of Mixed Tetravalent Uranium and Trivalent Lanthanide Complexes Associated with the Dipicolinate Ligand, in Aqueous Medium

The investigations of the chemical system involving tetravalent uranium associated with trivalent lanthanides (La, Ce, Nd, Sm–Er, Lu) and dipicolinic acid (H2dpa) led to the identification of six distinct types of heterometallic coordination complexes (I–VI). These compounds, obtained at room temperature from aqueous solution, have been characterized by single-crystal X-ray diffraction. They consist of tris-chelated dipicolinate uranium subunits {U(dpa)3} interacting with poly oxo/aquo or mixed polyoxo/aquo chelated dipicolinate lanthanide subunits (LnO1–3(H2O)5–8 or Ln(dpa)O0–3(H2O)4–6) in different arrangements. Complex I (La, Ce) exhibits the assembly of molecular dinuclear [ULn] and [ULnU] trinuclear units, with a linkage between U and Ln via bidentate carboxylate groups of the dipicolinate molecules. The same carboxylate bridging connection mode creates a linear chainlike coordination polymer in complex II (La, Ce), with a strict alternating U–Ln sequence. Complex III (Ce, Nd) contains an octanuclear...

An intramolecular antiferromagnetically coupled pentanuclear Mn(II) cluster containing acetate and tetracarboxylate linkers: Synthesis, structure and magnetism

A new Mn(II) complex {[Mn5(CH3COO)2(L)2(DMF)8](DMF)}n (1), (H4L = 3,5-bis(3′,5′-dicarboxylphenyl)-1H-1,2,3-triazole), has been synthesized and structurally characterized. The complex 1 have pentanuclear Mn(II) core, where the two sides of metal centers (Mn2 and Mn3) have trigonal bipyramidal arrangement and the middle metal center (Mn1) have octahedral environment utilizing two O atoms from adjacent bridging bidentate carboxylate groups and four O atoms from four coordinated DMF molecules. The planar arrangement of pentanuclear Mn(II) atoms are linked by L linkage to generate two dimensional sheet. The magnetic property of the compound indicates χMT value for the five Mn(II) unit to be 21.3 cm3 K mol−1 at 300 K, which is close to the spin-only value (21.9 cm3 K mol−1) for the pentamer having S = 5/2. Also, the Hirshfeld surface analyses have been performed which indicated the absence of weak Mn···Mn interaction thereby corroborating the results of observed magnetic properties.

A series of lanthanide complexes with 2,3-dichlorobenzoic acid and 2,2:6′,2″-terpyridine: Crystal structures, spectroscopic and thermal properties

Three new binuclear solid lanthanide complexes with the general formula [Ln(2,3-DClBA)3(terpy)(H2O)]2(Ln=Pr(1), Sm(2), Eu(3); 2,3-DClBA=2,3-dichlorobenzoate; terpy=2,2′:6′2″-terpyridine), have been synthesized and characterized. The powder XRD and single-crystal structures of the title complexes indicate that all the complexes are isomorphous. The two lanthanide ions in each complex are linked by two bridging bidentate carboxylate groups. Under ultraviolet light excitation, the europium complex exhibited characteristic red fluorescence of Eu3+(5D0→7F1–4). The thermal decomposition mechanism is investigated by TG/DSC–FTIR technology. The 3D stacked plots for the FTIR spectra of the evolved gases were recorded and the gaseous products were identified by the typical IR spectra obtained at different temperatures from the 3D stacked plots.

Magnetic and Spectroscopic Study on a New Asymmetric Mixed‐valence Mn2(II,III) Coordination Compound

Abstract A new dinuclear mixed‐valence compound [MnIIMnIII(bttpnol)(O2C–C6H4–NO2)2]ClO4 was synthesized by using the asymmetric heptadentate ligand N‐(2‐hydroxybenzyl)‐N,N′,N′‐tris(2‐pyridylmethyl)‐1,3‐diaminopropan‐2‐ol (H2btppnol). One central manganese atom assumes N3O3 and the other N2O4 coordination sphere. Both manganese ions are bridged by the alkoxy‐group of the dinucleating ligand and two bidentate carboxylate groups of the nitrobenzoate ligands. The structural data show clearly that MnIII prefers the more oxygen rich donor set. Cyclic voltammetry measurements reveal that the mixed‐valence state Mn2(II,III) could be reduced to Mn2(II,II) at E1/2(1) = –0.53 V and oxidized to Mn2(III,III) at E1/2(2) = 0.52 V (vs. ferrocene). Measurements of the magnetic susceptibility reveal a weak antiferromagnetic coupling with J = –8.5 cm–1. The mixed valence state was additionally confirmed by EPR spectroscopy showing the hyperfine signal of the S = 1/2 state of Mn2(II,III).

The synthesis and characterisation of strontium and calcium folates with potential osteogenic activity.

Compounds having the general formula MFO·4H2O where M = Ca or Sr and FO = a folate anion were prepared and their structure and physico-chemical properties were determined by elemental and thermal TGA, DSC analysis, FTIR, and EDAX spectroscopies and DRX. The results indicate that the two compounds form stable structures where folic acid acts as a self-bridging ligand via two bidentate carboxylate groups. Moreover the two compounds showed a low toxicity in vitro response as h-osteoblast cell viability was not negatively affected by the presence of folate derivatives within the range of 0.063-0.5 mg ml-1. The results also indicate that the folate derivatives that are formed overcome the toxic effects related to free Sr2+ ions. The range of maximum cell viability corresponding with a concentration of SrFO falls within the in vitro physiologically active range for strontium while within the same range the strontium derivative showed a potential osteogenic activity as indicated by the overexpression of ALP activity.

DFT calculations, spectroscopic, thermal analysis and biological activity of Sm(III) and Tb(III) complexes with 2-aminobenzoic and 2-amino-5-chloro-benzoic acids

The complexes of Sm(III) and Tb(III) with 2-aminobenzoic acid (anthranilic acid, AA) and 2-amino-5-chlorobenzoic acid (5-chloroanthranilic acid, AACl) were synthesized and characterized based on elemental analysis, IR and mass spectroscopy. The data are in accordance with 1:3 [Metal]:[Ligand] ratio. On the basis of the IR analysis, it was found that the metals were coordinated to bidentate anthranilic acid via the ionised oxygen of the carboxylate group and to the nitrogen of amino group. While in 5-chloroanthranilic acid, the metals were coordinated oxidatively to the bidentate carboxylate group without bonding to amino group; accordingly, a chlorine-affected coordination and reactivity-diversity was emphasized. Thermal analyses (TGA) and biological activity of the complexes were also investigated. Density Functional Theory (DFT) calculations at the B3LYP/6-311++G (d,p)_ level of theory have been carried out to investigate the equilibrium geometry of the ligand. The optimized geometry parameters of the complexes were evaluated using SDDALL basis set. Moreover, total energy, energy of HOMO and LUMO and Mullikan atomic charges were calculated. In addition, dipole moment and orientation have been performed and discussed.

Picolinate-containing macrocyclic Mn2+ complexes as potential MRI contrast agents.

We report the synthesis of the ligand Hnompa (6-((1,4,7-triazacyclononan-1-yl)methyl)picolinic acid) and a detailed characterization of the Mn(2+) complexes formed by this ligand and the related ligands Hdompa (6-((1,4,7,10-tetraazacyclododecan-1-yl)methyl)picolinic acid) and Htempa (6-((1,4,8,11-tetraazacyclotetradecan-1-yl)methyl)picolinic acid). These ligands form thermodynamically stable complexes in aqueous solution with stability constants of logKMnL = 10.28(1) (nompa), 14.48(1) (dompa), and 12.53(1) (tempa). A detailed study of the dissociation kinetics of these Mn(2+) complexes indicates that the decomplexation reaction at about neutral pH occurs mainly following a spontaneous dissociation mechanism. The X-ray structure of [Mn2(nompa)2(H2O)2](ClO4)2 shows that the Mn(2+) ion is seven-coordinate in the solid state, being directly bound to five donor atoms of the ligand, the oxygen atom of a coordinated water molecule and an oxygen atom of a neighboring nompa(-) ligand acting as a bridging bidentate carboxylate group (μ-η(1)-carboxylate). Nuclear magnetic relaxation dispersion ((1)H NMRD) profiles and (17)O NMR chemical shifts and transverse relaxation rates of aqueous solutions of [Mn(nompa)](+) indicate that the Mn(2+) ion is six-coordinate in solution by the pentadentate ligand and one inner-sphere water molecule. The analysis of the (1)H NMRD and (17)O NMR data provides a very high water exchange rate of the inner-sphere water molecule (kex(298) = 2.8 × 10(9) s(-1)) and an unusually high value of the (17)O hyperfine coupling constant of the coordinated water molecule (AO/ℏ = 73.3 ± 0.6 rad s(-1)). DFT calculations performed on the [Mn(nompa)(H2O)](+)·2H2O system (TPSSh model) provide a AO/ℏ value in excellent agreement with the one obtained experimentally.

Molecular and Polymeric Uranyl and Thorium Complexes with Sulfonate‐Containing Ligands

AbstractSix uranyl and one thorium(IV) cation complexes with ligands involving either only sulfonate or both sulfonate and carboxylate groups as complexing sites were obtained, mainly under hydrothermal conditions, and their crystal structures were determined. The uranyl ion complex with the 2‐sulfobenzoate (2‐SB2–) anion synthesized in the presence of pyridine, [pyH]4[(UO2)2(2‐SB)2O]2·4H2O (1), is a molecular, tetranuclear complex in which 2‐SB2– is chelating through its two functional groups, while [Th(2‐SB)2(H2O)3]·2H2O (2) is a 1D polymer with monodentate sulfonate and bridging bidentate carboxylate groups. Complex [(UO2)3K(4‐SB)O(OH)3(H2O)1.5]·0.5H2O (3), with the 4‐sulfobenzoate ligand, crystallizes as a 3D framework in which uranyl oxo/hydroxo 1D subunits are connected to one another by 4‐SB2– and potassium cation bridges, the latter being involved in as much as five bonds with uranyl oxo groups (“cation–cation” bonds). Complex [UO2(5‐SSH2)(H2O)3]2·2(5‐SSH2)·3H2O (4), with 5‐sulfosalicylic acid (5‐SSH3), is a dinuclear species in which the ligand is only coordinated through its bridging bidentate sulfonate group, an unusual occurrence. 5‐Sulfosalicylic acid undergoes partial desulfonation and carboxylation under hydrothermal conditions, yielding the heterometallic, tetranuclear complex [UO2Ni(5‐SHIPH)(4‐HIPH2)(bipy)2(H2O)]2·(4‐HIPH3) (5), 5‐sulfonato‐2‐hydroxyisophthalic acid (5‐SHIPH4) and 4‐hydroxyisophthalic acid (4‐HIPH3) being generated in situ. The all‐sulfonate ligand 1,2‐ethanedisulfonate (EDS2–) acts as a divergent linker in both [UO2(EDS)(H2O)3] (6) and [(UO2)2(EDS)(OH)2(phen)2]·4H2O (7). 1D polymers are formed in both cases, the doubly monodentate EDS2– ligand bridging isolated uranyl ions in 6 or hydroxo‐bridged uranyl dimers in 7. Sulfonate coordination to the 5f cation is present in all these complexes but 5, even in the absence of synergistic effects exerted by the stronger carboxylate ligating groups, and the variety of structures obtained in this as well as in previous work demonstrates that, together with the more investigated phosphonates, sulfonates are anions of great potential for the synthesis of actinide–organic coordination polymers and frameworks.

The cerium(III) coordination polymer with mixed polycarboxylic acids. Preparation of the CeO2 nanoparticles by thermal decomposition of the polymer

A treatment of benzene-1,2,4,5-tetracarboxylic acid (H4btc) and pyridine-2,6-dicarboxylic acid (H2pydc) with Ce(NO3)3·6H2O (in the molar ratio 1:1:2) under hydrothermal conditions led to the formation of a new 1D cerium(III) coordination polymer {[(pydc)2Ce2(μ-H2btc)(H2O)6]·4H2O}n (1). Compound 1 was characterized by infrared spectroscopy, elemental analyses and by X-ray diffraction studies. The polymeric chain of 1 contains cerium(III) ions bridged by H2btc2− ligand. Each H2btc2− ion is connected to four cerium(III) ions via its two bidentate and bridging carboxylate groups. Cerium(III) ion is nine-coordinated by three oxygen atoms from two different H2btc2− ligands, two oxygen atoms and one nitrogen atom from the tridentate pydc2− ligand and three coordinated water molecules, resulting with a distorted tricapped trigonal prismatic arrangement. Many hydrogen bonds of the O–H⋯O type are also present in the crystal structure of 1 and assemble the polymeric chains and the co-crystallized water molecules into a 3D architecture. The coordination polymer 1 was used for the preparation of the CeO2 nanoparticles. Synthesized CeO2 nanoparticles were characterized by infrared spectroscopy, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The face-centered cubic structure of CeO2 was determined by PXRD.

Physicochemical impact studies of gamma rays on “aspirin” analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of CO of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

Two new metal–organic frameworks based on cyclic dodecanuclear copper units

Two new metal–organic frameworks based on cyclic-type dodecanuclear copper units, (Me4N)6[Cu12(OMe)6(pz)6(BTC)6]·18H2O 1 and (Me4N)6[Cu12(OH)6(pz)6(BTC)6]·21H2O 2 (pz = pyrazolate, BTC = 1,3,5-benzenetricarboxylate), have been prepared by the solvothermal reactions of copper salts, Hpz and H3BTC ligands. The cyclic-type Cu12 unit in 1 and 2 is constructed by twelve CuII ions linked together by μ2-OH or μ2-OMe and unidentate carboxylate groups at the inner- and μ-pz and bidentate carboxylate groups at the outer surface of the toroid. In 1 and 2, each Cu12 unit is connected to 12 other units by BTC linkers, leading to 12-connected three-dimensional porous frameworks. The photocatalytic investigations indicate that compounds 1 and 2 exhibit photocatalytic activity for the degradation of RhB.

Catena-Poly[[[diaqua[3-(pyridin-4-yl)benzoato-κ2O,O′]gadolinium(III)]-bis[μ-3-(pyridin-4-yl)benzoato-κ2O:O′]] monohydrate

In the title coordination polymer, {[Gd(C12H8NO2)3(H2O)2]·H2O}n, the GdIII ion is ligated by one bidentate carboxyl­ate group, four monodentate bridging carboxyl­ate O atoms and two water mol­ecules. The resulting GdO8 polyhedron approximates to a square anti­prism. The bridging ligands link the metal ions into a [100] chain, with each pair of adjacent metal ions being bridged by two ligands. Inter-chain O—H⋯O and O—H⋯N hydrogen bonds help to establish the packing.

Tetrakis(μ-2-phenoxypropionato)-κ3O,O′:O′;κ3O:O,O′;κ4O:O′-bis[(1,10-phenanthroline-κ2N,N′)(2-phenoxypropionato-κ2O,O′)holmium(III)

The title compound, [Ho2(C9H9O3)6(C12H8N2)2], lies about a centre of symmetry and is comprised of six 2-phen­oxy­propionate (POPA) anions and two 1,10-phenanthroline (phen) ligands. The two HoIII ions are linked by four POPA groups utilizing both bi- and tridentate bridging modes to form an inversion-symmetric dimer. Each HoIII ion is nine-coordinate, with a chelating 1,10-phenanthroline mol­ecule, one bidentate chelating carboxyl­ate group, two bidentate bridging carboxyl­ate groups and two tridentate bridging carboxyl­ate groups in a distorted mono-capped square anti­prism geometry. There are weak π–π aromatic inter­actions between the phen groups and aromatic rings of the POPA ligands [centroid–centroid distance = 3.829 (1) Å].

Catena-Poly[[[aquabis(4,4′-bipyridine-κN)zinc]-μ-L-tyrosinato-κ3N,O1:O1′] nitrate dihydrate

In the title compound, {[Zn(C9H10NO3)(C10H8N2)2(H2O)]NO3·2H2O}n, the ZnII atom is six-coordinated in a distorted octa­hedral geometry by two carboxyl­ate O atoms and one amino N atom from two l-tyrosinate ligands, two N atoms from two 4,4′-bipyridine ligands, and one water mol­ecule. Adjacent Zn atoms are bridged by the bidentate carboxyl­ate groups into a cationic chain extending along [010]. N—H⋯N, O—H⋯N and O—H⋯O hydrogen bonds link the cationic chains, nitrate anions and uncoordinated water mol­ecules into a supra­molecular network. π–π inter­actions between the pyridine rings and between the pyridine and benzene rings [centroid–centroid distances = 3.615 (4) and 3.636 (4) Å] are present.