A 3-D pillar-layered coordination polymer {[EuCu(C2O4)(na)2] · 2H2O} n : synthesis,structure and photoluminescent properties

A 3d–4f heterometallic coordination polymer, {[EuCu(C₂O₄)(na)₂] ·?2H₂O} _n (1) [Hna=nicotinic acid], has been synthesized by hydrothermal reaction of lanthanide oxides, Cu(I), and pyridine-2,3-dicarboxylic acid. 1 features a 3-D pillar-layered coordination framework constructed from two-dimensional lanthanide-carboxylate layers and Cu(na) pillars. Interestingly, the na ligand was obtained by the in situ decarboxylation of pyridine-2,3-dicarboxylic acid.     

Syntheses and characterization of three lanthanide(III) complexes containing pyridine-3,5-dicarboxylic acid and oxalic acid ligands

Direct reaction of pyridine-3,5-dicarboxylic acid (H₂PDA) and oxalic acid (H₂ox) with Ln(ClO₄)₃ · nH₂O under hydrothermal conditions gave three 3-D coordination networks, [Ln(PDA)(ox)_0.5(H₂O)₂] · H₂O [Ln = La(1), Nd(2), and Eu(3)]. The complexes were characterized by elemental analysis (EA), X-ray single-crystal diffraction, infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Single crystal X-ray diffractions shows that the compounds are isomorphous and have 3-D framework structures, in which pyridine-3,5-dicarboxylates (PDA^2?) link lanthanides to give 2-D layers, which are further fabricated into a 3-D network via bis-bidentate oxalate bridging. Luminescence of 3 is investigated.     

Thermal and spectroscopic studies of sodium and light lanthanide (III) complexes with 2,4-pyridinedicarboxylate anion

Pyridine-2,4-dicarboxylic acid (lutidinic acid) is next one after pyridine-2,5-dicarboxylic acid of the six isomers which lanthanide complexes were studied thermally and spectrally. New complexes synthesized with light lanthanides (III) with general formula Ln₂L₃·nH₂O, where n?=?7.5; 8; 8.5; 9, were obtained. Sodium salt was obtained as hexahydrated compound. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), and Gd(III) are thermally stable up to 303?C313?K. Dehydration process run for all compounds in one stage, anhydrous compounds decompose through appropriate light lanthanides (III) oxalates, oxocarbonates, carbonates to metal oxides. Theoretical IR and Raman studies were carried out in order to identify precisely characteristic group bands vibrations present on IR and Raman spectra.     

Thermal and spectroscopic properties of light lanthanides (III) and sodium complexes of 2,5-pyridinedicarboxylic acid

Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln₂L₃·nH₂O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na₂L·H₂O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas Na₂L·H₂O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm⁻¹ disappear on complex spectra and ν_as and ν_s of COO⁻ groups appear thus indicating that complexation process took place.     

Crystal structure,bioactivities, and electrochemistry properties of four diverse complexes with a new pyrazole ligand

Four complexes, [Cu(cmpa)(Hpdbl)] ? 2H₂O (1), [Cd(cmpa)₂] ? 2.5H₂O (2), [Cu(cmpa)₂] ? 2.5H₂O (3), and [Pb(cmpa)₂] · 2.5H₂O (4), have been synthesized and characterized based on the pyrazole ligand (Hcmpa = 3-chloro-6-(3,5-dimethy-1-yl)picolinic acid, H₂pdbl = pyridine-2,6-dicarboxylic acid). Complexes 1–4 showed 3-D supramolecular architectures that are connected through hydrogen bonds and aromatic π–π interactions. Preliminary antibacterial activities of the complexes indicated selective inhibition for the tested strains. The electrochemistry of 1–4 was studied by cyclic voltammetry in DMSO using a glassy carbon working electrode.     

Syntheses,crystal structures,and luminescence of carboxylato-bridged coordination compounds

Two 2-D metal carboxylate coordination compounds [Tb(pydc)(ox)_1/2(H₂O)₂] (1) and [Cd(pydc)(me)(H₂O)]₂ · H₂O (2) (pyridine-2,5-dicarboxylic acid = pydc, oxalic acid = ox, me = methanol) have been synthesized under hydrothermal conditions. Carboxylates are building blocks in the formation of zigzag chain and cockle stair-like chain structures for 1 and 2, respectively. Both the compounds have been structurally determined by single-crystal X-ray diffraction, and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and fluorescence spectra.     

New copper(II) complexes including pyridine-2,5-dicarboxylic acid: synthesis,spectroscopic, thermal properties,crystal structure and how these complexes interact with purified PON 1 enzyme

We report the synthesis of two square-pyramidal copper(II) complexes, [Cu(2,5-pydc)(2-aepy)(H₂O)]·H₂O, 1, and [Cu(2,5-pydc)(2-ampy)(H₂O)]·H₂O, 2 (2-aepy = 2-(aminoethyl)pyridine, 2-ampy = 2-(aminomethyl)pyridine, 2,5-pydc = pyridine-2,5-dicarboxylic acid or isocinchomeronic acid). The synthesized complexes have been characterized by X-ray diffraction, FT-IR, elemental, and thermal analysis techniques. The crystal structure of 1 was established by X-ray analysis. Powder X-ray diffraction analysis showed that the complexes are pure. The inhibition of human serum paraoxonase 1 (PON 1, EC 3.1.8.1) enzyme with these complexes were investigated. We used diethyl 4-nitrophenyl phosphate as a substrate to measure the paraoxonase activity of PON 1 enzyme spectrophotometrically. Complexes 1 and 2 decreased the in vitro PON 1 activity with different inhibition mechanisms. Complexes 1 and 2 inhibited paraoxonase activity of this enzyme as competitively and noncompetitively, respectively.     

Synthesis of several new lanthanide Glimepiride complexes for evaluation of microbial activity

The complexation between lanthanide metal ions like Nd(III), Tb(III), and Er(III) with Glimepiride produces 1: 1 molar ratio (metal: Glimepiride) monodentate complexes of general formula: [M(GMP)(H₂O)₄]Cl₃·xH₂O, where: M = Nd, Tb, and Er, x = 1, 10, respectively. The structures of obtained compounds were assigned by IR, ¹H NMR and UV/Vis spectra. Themogravimetric analysis and kinetic thermodynamic parameters have proved the thermal stability of Glimepiride complexes. Obtained lanthanide complexes showed significant effect against some bacteria and fungi.     

Synthesis,spectral, antimicrobial,and thermal properties of Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) gliclazide complexes

The complexation between the lanthanide metal ions Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) and gliclazide produced 1 : 1 molar ratio metal: gliclazide (Glz) complexes coordinated in a monodentate fashion via the OH group and having the general formulas [M(Glz)Cl₃(H₂O)]·xH₂O (M = Ce, Gd, Nd and x = 1, 3, 4, respectively) and [M(Glz)(H₂O)₄]Cl₃·yH₂O (M = Tb, Er and y = 1, 2, respectively). The structure of the synthesized lanthanide gliclazide complexes was assigned by IR, ¹HNMR, and UV-Vis spectroscopy. Thermal analysis and kinetic and thermodynamic parameters gave evidence for the thermal stability of the Glz complexes. The latter showed a significant antimicrobial effect against some bacteria and fungi.     

An evaluation of primary water standards by TG/DTA and vapor sorption analysis

The thermal behavior of [Ca(H₂O)₃(2,3-pydcH)₂] _n (I), [Cd(H₂O)₃(2,3-pydc)] _n (II), and [Cd(H₂O)₆][Cd(2,3-pydcH)₃]₂ (III) complexes with pyridine-2,3-dicarboxylic acid was monitored by TG, DTG, and DSC analysis, where 2,3-pydcH—mono deprotonated pyridine-2,3-dicarboxylic acid and 2,3-pydc—doubly deprotonated dicarboxylate anion. Thermal decomposition of these compounds go through one or two dehydratation stages, followed by the loss of organic matter. The final decomposition products are found to be the corresponding metal oxides. The possible scheme of destruction of the complexes have been used to reveal the relationships between stability and molecular structure.     

Cadmium(II), manganese(II) and zinc(II) compounds

Three new compounds, [Cd(μ ₃ -Hpdh)(μ₂-Cl)] _n (1), Mn(Hpdh)₂(H₂O)₂ (2) and Zn(Hpdh)₂ (H₂O)₂ (3) (H₂pdh =?pyridine-2,3-dicarbo-2,3-hydrazide), have been synthesized and characterized by elemental analysis, IR spectra, TG and single-crystal X-ray diffraction. Under hydrothermal conditions, H₂pdh is generated by an in situ acylation of H₂pda (H₂pda =?pyridine-2,3-dicarboxylic acid) with hydrazine hydrate. Complex 1 features a 2D layer structure constructed by a dinuclear Cd(II) building block. In complexes 2 and 3, hydrogen bonding interactions connect mononuclear structures into 3D supramolecular frameworks.     

A comparison of solution and solid state coordination environments for calcium(II), zirconium(IV), cadmium(II) and mercury(II) complexes with dipicolinic acid and methylimidazole derivatives

Four new supramolecular compounds, (2-mimH)[Ca(pydcH)₃][Ca(pydcH₂)(pydc)(H₂O)₂]·4H₂O (1), (1-mimH)₂[Zr(pydc)₃] (2), (2-mimH)₂[Cd(pydc)₂]·8H₂O (3), and (2-mimH)₂[Hg(pydc)₂]·8H₂O (4) [where pydcH₂ = pyridine-2,6-dicarboxylic acid (dipicolinic acid), 1-mim = 1-methylimidazole, and 2-mim = 2-methylimidazole], have been synthesized and characterized by elemental analyses, spectroscopic techniques (IR, UV–vis, ¹H NMR, and ¹³C NMR), thermal (TG/DTG/DTA) analysis as well as single-crystal X-ray diffraction. All four compounds are proton-transfer salts of the methylimidazolium cations and metal complex anions that crystallized from a solution of pyridine-2,6-dicarboxylic acid, methylimidazole, metal nitrates or chlorides as starting materials. The coordinating dicarboxylic acid is deprotonated at the carboxyl group and methylimidazole is protonated to balance the charge. In the crystal structures of 1–4, hydrogen bonding and π–π stacking play important roles. Water clusters are formed in 1, 3, and 4. The equilibrium constants of dipicolinic acid (pydc) and methylimidazole derivatives (1-mim and 2-mim), pydc-2-mim, pydc-1-mim proton-transfer systems as well as those of their complexes were investigated by a potentiometric pH titration method. The stoichiometries of most of the complex species in solution were very similar to the cited crystalline metal ion complexes.     

Synthese,Kristallstrukturen und Eigenschaften von Lanthanoid(III)-Komplexen mit 7-Oxa-bicyclo[2.2.1]heptan-2,3-dicarbonsäure

Synthesis, Crystal Structures, and Properties of Lanthanoid(III) Complexes with 7-Oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic Acid The synthesis of coordination compounds [ML(HL)(H₂O)] with M = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺ and H₂L = 7-oxa-bicyclo[2.2.1]heptane-2-exo,3-cis-dicarboxylic acid ( 1 ) has been described. Results of IR spectroscopy and thermal decomposition are given. As a result of X-ray analyses, the four investigated lanthanoid(III) complexes are isotypic. Their stereochemistry approximates to the tri-capped trigonal prism with nine O atoms coordinating the metal atom. The bicyclic ligand acts as a tridentate chelating monoanion HL^? as well as a pentadentate dianion L^2? with both chelating and bridging function. One coordination place at the metal atom is occupied by a water molecule.     

Studies on complex compounds of thorium(IV) with pyridine and quinoline carboxylic acid. Part I

Summary Thorium acetylacetonate [Th(acac)₄] reacts with pyridine carboxylic acids in acetone giving eight coordinate thorum(IV) complexes of the compositions [Th(pic)₄] and [Th(picO)₄] (picH = picolinic acid, picOH = picolinic acidN-oxide). The complex [Th(dip)₂] · 3H₂O (dipH₂ = pyridine-2,6-dicarboxylic acid) is also reported. Thorium(IV) complexes of the types [Th(quin)₂] · 2H₂O and [Th(quind)₂(acac)₂] (quinH₂ = quinolinic acid or pyridine-2,3-dicarboxylic acid, quindH = quinaldinic acid) were prepared by the interaction of [Th(acac)₄] with the respective acids in acetone. The lower solubility and i.r. spectral studies of the complex [Th(quin)₂] · 2 H₂O suggest that it is polymeric.     

A phenyl imidazole dicarboxylate-based 3D terbium–organic framework for selective sensing of nitrobenzene

A novel lanthanide(III)–organic framework, {(Tb(μ₃-HPhIDC)(μ₂-C₂O₄)_0.5(H₂O))·2H₂O}_n (1) (H₃PhIDC = 2-phenyl-1H-imidazole-4,5-dicarboxylic acid) has been solvothermally synthesised and structurally characterised, which exhibits selective detection of nitrobenzene via a photoinduced electron transfer quenching mechanism. The high efficiency, stability and recyclability of 1 make it a potential chemosensor for nitrobenzene.     

Synthesis and crystal structures of two metal-nitroxide complexes including a phenanthroline-substituted nitroxide radical

Two metal-nitroxide complexes, [Cu(IMPhenCOO)(CH₃OH)]₂ ·?(NO₃)₂ (1) and [Co(NIT2Py)(H-2,5-PDA)₂] ·?0.5CH₃OH ·?2H₂O (2) (IMPhenCOOH =?2-carboxyl-9-(4,4,5,5-tetramethylimidazoline-1-oxyl-2-yl)-1,10-phenanthroline, NIT2Py =?2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and H₂-2,5-PDA =?pyridine-2,5-dicarboxylic acid), have been synthesized and structurally characterized by X-ray diffraction. Complex 1 exists as discrete binuclear molecules and each copper(II) is five-coordinate with one tridentate radical ligand (IMPhenCOOH), the other radical ligand through one carboxyl oxygen and one methanol molecule. Complex 1 is the first structurally characterized complex containing the phenanthroline-substituted nitroxide radical. In 2, the Co(II) is six-coordinate with one radical ligand (NIT2Py) and two bidentate pyridine-2,5-dicarboxylate anions.     

Mixed ligand complexes of ruthenium(III), rhodium(III) and iridium(III) with dipicolinic acid and some monobasic bidentate nitrogen,oxygen donor ligands

The trivalent ruthenium, rhodium and iridium complexes of dipicolinic acid and its mixed ligand complexes with several nitrogen, oxygen donor molecules, of types: Na[M(dipic)₂]·2H₂O and [M(dipic)(N-O)]·nH₂O (where M = Ru(III), Rh(III) or Ir(III); dipicH₂ = dipicolinic acid; NOH represents different nitrogen, oxygen donor molecules, viz., picolinic acid, nicotinic acid, isonicotinic acid, glycine, aminophenol, o- or p-aminobenzoic acid), have been synthesized and characterised on the basis of elemental analyses, electrical conductance, magnetic susceptibility measurements and spectral (electronic and infrared) data. The parent dipicolinic acid complexes are found to have a six-coordinate pseudooctahedral structure, whereas for mixed ligand complexes, a polymeric six-coordinate structure has been assigned. Various ligand field and nephelauxetic parameters have also been evaluated.     

Synthesis,structure, and photoluminescence of a series of lanthanide coordination polymers constructed from nitrogen containing organic ligands

We have synthesized four coordination polymers with two different nitrogen containing organic ligands and different lanthanide metal ions, under hydrothermal condition. [{Ln₂(bpdc)₃(H₂O)₂}] _n (Ln = Dy (1), Sm (2)) (bpdc = 2,2-bipyridine-3,3-dicarboxylic acid) are isostructural, with 2-D supramolecular layer structure composed from 1-D chains. Like 1 and 2, [{Ln(pzda)₂(H₂O)₂} · 4H₂O] _n (Ln = Dy (3), Nd (4)) (pzda = pyrazine-2,6-dicarboxylic acid) are also isostructural with 1-D chain-like structures. The photoluminescence of 2 is studied.     

Copper(II) complexes with pyridine-2,6-dicarboxylic acid from the oxidation of copper(I) iodide

Via an oxidation reaction of Cu(I) iodide with pyridine-2,6-dicarboxylic acid (H₂L) in DMF three copper(II) complexes, [(CH₃)₂NH₂]₂[CuL₂] (1), K₂[CuL₂]?H₂L?H₂O (2) and [Cu(L)(H₂O)]_n (3), were synthesized and characterized. The structures of 1–3 were determined by single crystal X-ray diffraction studies. In-situ DMF decomposition produces dimethylamine base under solvothermal conditions and a proton transfer reaction takes place for the complex formation of 1. 3-D networks are stabilized in 1 and 2 via hydrogen bonds. Complex 3 is a 1-D coordination polymer with Cu-O semi-coordination bonds. Thermal decomposition of the complexes results in the corresponding metal oxides. Also, the electrochemical behavior of 1 was determined to be a metal-centered and diffusion-controlled, one-electron reduction process.     

Assembly of three 3-D MOFs from 2-phenyl-4,5-imidazole dicarboxylate and oxalate

Three lanthanide–organic polymers, {[Ln(μ ₃-HPhIDC)(μ ₂-C₂O₄)_0.5(H₂O)]?·?2H₂O} _n (Ln?=?Nd (1), Sm (2), and Tb (3)), have been isolated from the reaction of 2-phenyl-1H-imidazole-4,5-dicarboxylic acid (H₃PhIDC) with equal amount of Ln(III) salts under solvothermal condition with the rigid coligand oxalate. The three polymers, which are isomorphous and isostructural, have been structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. Each exhibits a 3-D framework constructed from infinite 2-D layers joined by μ ₂-C₂O₄, which are composed of μ ₃-HPhIDC^2? and trivalent lanthanide. Thermal properties have also been investigated.