Structure and physical properties of a novel three-dimensional nickel coordinated polymer with mixed ligands resulting from hydrothermal reaction

The neutral three-dimensional metal coordination polymer [Ni₂(4,4^′-bpy)₂(btc)(H₂O)₂]_n·2nH₂O (4,4^′-bpy=4,4^′-bipyridine, btc=1,2,4,5-benzenetetracarboxylate) has been prepared from hydrothermal reaction of nickel(II) chloride with mixed ligands in basified aqueous solution. The magnetic study reveals that there exist ferromagnetic interactions between nickel(II) atoms. The TGA and XRPD analyses suggest that the crystallization and coordination water molecules play important roles in the formation and stabilization of the polymer and the title compound has potential applications.     

Synthesis and crystal structure of a novel zinc(II) coordination polymer with mixed ferrocenyl diketone and bipyridine ligands

A novel zinc(II) coordination polymer [Zn(fca)₂(bpe)]_n·2nH₂O (bpe=1,2-bis(4-pyridyl)ethene, fca=C₅H₅FeC₅H₄C(OH)CHCOCH₃) was obtained by the reaction of Zn(OAc)₂·2H₂O with bpe and 1-ferrocenylbutane-1,3-dione (ferrocenoylacetone, Hfca) in methanol solution. X-ray structural analysis reveals that the compound contains two kinds of ligands: one is the 1,2-bis(4-pyridyl)ethene ligand, directly bridging zinc(II) centers to form a one-dimensional chain [Zn(bpe)]_n, the other is the enolized ferrocenylacetone chelating the central ion. The zinc(II) ion is in an elongated octahedral environment with four oxygen atoms from two distinct enolized ferrocenoylacetone, two nitrogen atoms of the bridging 1,2-bis(4-pyridyl)ethene ligands.     

Synthesis,Crystal Structure and DNA Interaction of a Novel Three-Nuclear Cobalt(II) Complex with Schiff Base Derived from 4-Chloroanthranilic Acid and 2,4-Dihydroxybenzaldehyde

A novel transition metal coordination polymer [Co₃(C₁₄H₈NO₄Cl)₄(CH₃OH)₄·4CH₃OH]_n with Schiff base (C₁₄H₈NO₄Cl: 4-chloroanthranilic acid- 2,4-dihydroxybenzaldehyde) was synthesized using 4-chloroanthranilic acid, 2,4-dihydroxybenzaldehyde and cobalt(II) acetate as source, and its structure was characterized by IR spectroscopy, elemental analysis, ¹H NMR and single crystal X-ray diffraction. X-ray crystallography shows that every cobalt atom is six-coordinated. Two cobalt atoms on the two sides are respective coordinated with two nitrogen atoms from –C=N–, two carboxylic oxygen atoms and two hydroxyl oxygen atoms in different ligands, while the cobalt atom in the middle links two ligands on the side through two carboxylic oxygen atoms and coordinates with four oxygen atoms of methanol, forming a three-nuclear Co(II) complex. The complex forms a two-dimensional layer structure through O–H···O intermolecular hydrogen bonds. The interaction of the Co(II) complex with calf-thymus DNA (CT-DNA) was investigated by UV absorption spectroscopy, fluorescence emission spectroscopy, viscosity and cyclic voltammetry. All measurements revealed that the Co(II) complex binds to DNA via a intercalative mode.     

1D Hydrogen-Bonded Polymers Assembled by Tetraaza Macrocyclic Metal(II) Complexes and Inorganic Salts

The self-assembly of [M(L)]Cl₂·2H₂O (M = Ni²⁺ and Cu²⁺, L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) with sodium 1,2,4-benzenetricarboxylate (Na₃btcb) and KNO₃ generates the 1D hydrogen-bonded polymers with formulas [Ni(L)(H₂btcb^?)₂] (1) and [Cu(L)(NO₃)₂] (2). These polymer complexes have been characterized by X-ray crystallography, spectroscopy and cyclic voltammetry. The crystal structure of 1 shows a distorted octahedral coordination geometry around the nickel(II) ion, with the four secondary amines of the macrocycle and two carboxylate oxygen atoms of the H₂btcb^? ligand in the trans position. In 2, the coordination environment around the central copper(II) ion reveals an axially elongated octahedron with four Cu–N bonds and two oxygen atoms of the nitrate ligand in the trans position. The cyclic voltammograms of the complexes undergo two one-electron waves corresponding to M^II/M^III and M^II/M^I processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature of the axial ligands.     

Mixed Solvothermal Synthesis of a New Heterometallic Coordination Polymer Containing Two Distinct Inorganic Cd–O–Ca Chains

A new heterometallic coordination polymer, namely [Cd₂Ca₂(PBDC)(H₂O)₂(e-urea)(DMF)]_n·2n(DMF) (1 H₂PBDC = terephthalic acid, DMF = N,N-dimethylformamide, e-urea = ethyleneurea) has been synthesized by combining the PBDC ligand with Cd(II) and Ca(II) salts under mixed solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 is an extended three-dimensional framework containing two distinct inorganic Cd–O–Ca chains, and can be simplified into a 4-connected topological network based on three unequivalent nodes. Luminescent study reveals that 1 exhibits strong, ligand-centred luminescence in the solid-state at room temperature.     

Ligand configuration introduced into a 3D self-interpenetrated coordination polymer as visible-light-driven photocatalyst

The combination of 1,4-bis(imidazol-1-ylmethyl)benzene (BIYB) and anthraquinone-2,7-disulfonic acid (H₂AQDA) ligands leads to a copper coordination polymer, namely, {[Cu(BIYB)₂(AQDA)]·H₂O}_n (1). The cis-BIYB ligands link one unique Cu(II) atoms to give 1D double chains, but trans-BIYB connects the other Cu(II) centers to generate 2D (4,4)-layers. Each H₂AQDA ligand acts as a μ₂-bridging linking the double chains and (4,4)-layers to generate the 3D framework of 1. Cu(1) and Cu(2) can be viewed as 6- and 4-connected nodes, which lead to a (4,6)-connected self-penetrated network. Notably, complex 1 represents the rare example of coordination polymer-based visible-light-driven photocatalyst, and shows good degradation efficiency of organic dye.     

Synthesis,Structure, Photoluminescent and Drug Loading and Release Properties of a Novel Cadmium (II) Coordination Polymers Based on Terphenyl–3, 4″, 5–tricarboxylic Acid

A stable three-dimensional coordination complex, {[Cd_1.5(tta)(H₂O)_4.5]·H₂O}_n (1) (tta?=?terphenyl—3,4″,5—tricarboxylic acid), was prepared by the solvothermal reaction of Cd(CH₃COO)₂·2H₂O and tta in water, which was characterized by infrared spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction, fluorescence, and thermogravimetric analyses. In the solid state of this compound, the Cd (II) center displayed a distorted trigonal bipyramid coordination sphere consisting of two oxygen atoms from two different carboxyl which were offered by two separate tta ligands and three oxygen atoms from three water molecules. The one-dimensional linear (1D) structure and two-dimensional plane were formed by Cd-O coordination bond while the 3D supramolecular reticular structure was formed by hydrogen-bond interactions. And there are large rectangular holes whose size are 13.30?×?13.31 Å along crystallographic axis a. The drug loading content (DLC) of 1 was 0.203 g (Ibu)/g (compound) and the release was desirable.     

Synthesis and Structure of 1D Copper(II) Polymers with Dissymmetrical N,N′-Bis(substituted)oxamide Ligands: Cytotoxicity and DNA-Binding Property

Two one-dimensional copper(II) coordination polymers with different dissymmetrical N,N′-bis(substituted)oxamide ligands were synthesized, namely {[Cu₂(dmaepox)(dabt)]pic·H₂O}_n (1) and {[Cu₂(dmapob)(dabt)]NO₃·0.6H₂O}_n (2), where H₃dmaepox and H₃dmapob stand for N-(2-carboxylatophenyl)-N′-[3-(methylamino)propyl]oxamidate and N-(2-carboxylatophenyl)-N′-[3-(dimethylamino)propyl]oxamidate, respectively, and dabt is 2?2′-diamino-4?4′-bithiazole. Polymer 1 was characterized by elemental analyses, IR and electronic spectra and single-crystal X-ray diffraction. The crystal structure reveals that polymer 1 consists of many binuclear copper(II) units bridged by cis-oxamide and carboxylate groups. The two copper(II) ions are located in square-planar and square-pyramidal coordination environments, respectively. The separations of the Cu(II) atoms bridged by oxamide and carboxylate groups are 5.2035(7) and 5.1196(7) Å, respectively. The crystal structure of polymer 2 has been reported in our previous paper. However, its relative properties were not studied. In order to compare the influence of different bridging ligands on the cytotoxicities and DNA-binding properties, the cytotoxicities and reactivities towards DNA of polymers 1 and 2 were investigated. The results suggest that the two polymers can interact with herring sperm DNA in the mode of intercalation with binding affinities following the order of 1 > 2, and this is consistent with their in vitro cytotoxicities.     

Structure and magnetic properties of A Cu(II) coordination polymer supported by a tetrapodal Schiff base ligand

A Cu(II) Schiff base coordination polymer, {[Cu₃L(μ₂-NO₃)₂·(H₂O)₂].3H₂O}_n, is readily prepared by complexation of the tetrapodal Schiff base, H₄L (H₄L = 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane), with cupric nitrate trihydrate. It has been demonstrated that the coordination polymer consists of linear trinuclear Cu(II) entities, and displays a cooperative coordination mode for nitrate anions, coordinated water molecules, and Schiff base ligands to Cu(II) ions. In addition, variable-temperature magnetic susceptibility measurements reveal a strong antiferromagnetic coupling interaction between adjacent copper(II) ions with large J value of − 289.66 cm^− 1.     

Synthesis,Crystal Structure and Luminescent Property of a New Zn(II) Coordination Polymer with Twofold Interpenetrated pcu Topology

A new Zn(II) coordination polymer; namely, [Zn(FA)(bmix)_0.5] _n ·nH₂O (1, H₂FA = fumaric acid, bmix = 1,4-bis(2-methyl-1H-imidazol-1-ylmethyl)benzene) was synthesized with fumaric acid and flexible 2-methylimidazole-based ligands with Zn(II) salts under hydrothermal conditions. Single-crystal X-ray diffraction reveals that 1 features a twofold interpenetrating three-dimensional pillar-layered framework based on paddle-wheel shaped [Zn₂(COO)₄] subunits. The structure may be simplified to a 6-connected pcu topological network. Luminescent investigation reveals that 1 exhibits intense ligand-centered fluorescence at room temperature.     

Hydrogen-bonding organization of (4,4) coordination layers into a 3-D molecular architecture with channels clathrating guest molecules [Cu(tdc)(bpy)(H2O)](bpy) (tdc=thiophine-2,5-dicarboxylate; bpy=4,4′-bipyridine)

The hydrothermal reaction of Cu(OAc)₂ · H₂O with thiophene-2,5-dicarboxylic acid (H₂tdc) and 4,4^′-bipyridine (bpy) gave a copper(II) coordination polymer {[Cu(tdc)(bpy)(H₂O)](bpy)}_n (1), in which the (4,4) layers are assembled via strong hydrogen bonds between the aqua ligands and the uncoordinated carboxylate oxygen atoms into a porous 3-D molecular architecture with parallelogrammic channels. The guest bpy molecules reside in the channels, involving intermolecular C–H⋯N hydrogen bonds with the host framework, can be removed upon heating at reduced pressure.     

Hydrothermal Synthesis, Crystal Structure and Characterization of New Coordination Polymer [Co2(pydc)2(H2O)6] n ·2nH2O

A coordination polymer of cobalt(II) containing the pyridine-2,5-dicarboxylate (pydc) ligand and having the composition [Co₂(pydc)₂(H₂O)₆] _n ·2nH₂O was prepared by the hydrothermal method. The coordination polymer was characterised by FTIR, single crystal XRD, SEM, TGA–DTA, and N₂ Temperature Programmed Desorption, Brunauer, Emmett and Teller surface area. The polymer contains two cobalt(II) ions with slightly distorted octahedral geometry. The carboxylate group at the 2-position of pyridine acts as a bridging ligand between two cobalt metal ions and this expansion leads to formation of a 1-D chain-like coordination polymer. The coordination polymer chains are packed together by well-directed hydrogen bonds to generate a three dimensional mesoporous network. The N₂ TPD study shows that the polymer is mesoporous in nature and possesses slit-shaped mesopores with average pore size diameter of 17.78 nm. SEM micrographs show well-defined channels in the solid crystals confirming the porosity of polymer. Thermogravimetric studies indicate the robust nature of the polymer. The polymer undergoes thermal decomposition in well-defined steps leading to the formation of cobaltous oxide as the end-product.     

Preparation of a Novel Nano-scale Lead (II) Zig-Zag Metal–Organic Coordination Polymer with Ultrasonic Assistance: Synthesis,Crystal Structure,Thermal Properties,and NBO Analysis of [Pb(μ-2-pinh)N<Subscript>3</Subscript> H<Subscript>2</Subscript>O]<Subscript>n</Subscript>

A novel nano-cauliflower-shaped lead(II) metal–organic coordination polymer, [Pb(μ-2-pinh)N₃ H₂O]_n (1), was synthesized using an ultrasonic method. The nanostructure was characterized by scanning electron microscopy (SEM), X-ray powder diffraction, IR spectroscopy, elemental analysis, and thermal analysis. The compound was structurally characterized by single-crystal X-ray diffraction. The coordination compound takes the form of a zig-zag one-dimensional polymer in solid state. The coordination number of the lead(II) ions is six (PbN₄O₂) with three nitrogen atoms and one oxygen atom from two linker organic ligands, as well as one oxygen from coordinated water and one nitrogen atom from terminal coordinated azide anion. It has a stereo-chemically active lone electron pair, and the coordination sphere is hemidirected. The zig-zag 1D chains interact with neighbouring chains through weak interactions, creating a 3D supramolecular metal–organic framework. Lead oxide nanoparticles were obtained by thermolysis of the new nano coordination compound at 180 °C with oleic acid as a surfactant. The morphology and size were further studied using SEM. Natural bond orbital analyses demonstrate the electronic properties of the lead centre and other atoms.     

A 3D Porous Coordination Polymer from Tetrazole Ligand and Cd(II): Crystal Structure,Luminescent Property and Adsorption of Methanol and Water

An unusual tetrazole-based Cd(II) coordination polymer, [Cd(4-tzba)(H₂O)]_n (tzba = 4-(tetrazolyl)benzenecarboxylic acid) (1), was synthesized by hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. The structure of 1 contains distorted octahedral cadmium centers coordinated by four different tzba^2? ligands and a water molecule. All the tzba^2? ligands display coordination of type, μ4-κN1:κN3:κN4:κO1, O2, which connects four Cd(II) atoms to form an intricate 3-D network. There are three kinds of apertures in the structure of 1; two helical channels and a hexagonal aperture are observed along different axes. Polymer 1 exhibits selective gas adsorption behavior for methanol, ethanol and water. In addition, 1 shows blue photoluminescence mainly arising from intraligand transitions of the aromatic rings in the tbza^2? ligand.     

A transition metal complex containing pyrazine-2,5-dicarboxylato bridging ligands: a novel three-dimensional manganese(II) compound

The novel metal-organic polymer [Mn(μ₄-pzdc)]_n (H₂pzdc=pyrazine-2,5-dicarboxylic acid) has been synthesized by the hydrothermal reaction of Mn(NO₃)₂ · 4H₂O with H₂pzdc. X-ray diffraction analysis shows that the polymer exhibits an extended three-dimensional network with hexadentated pzdc ligands bridging four manganese(II) atoms. The magnetic measurements show the occurrence of weak antiferromagnetic couplings.     

Structural Variations in Coordination Polymers of Sodium and Cesium Dicarboxylates

The coordination polymer {[Na₂L(μ-H₂O)(H₂O)₃]·H₂O} _n (1) derived from 2,2′-(phenylmethylidene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H₂ L) has repeat units comprising of hexa-coordinate diaqua-bridged dinuclear sodium complex ions. These units are connected through intervening mononuclear complex parts having penta-coordinated sodium ions. The sodium ions adopt repeated hexameric chair-like arrangement in the polymer. The cesium salt of H₂ L namely [Cs(HL)(μ-H₂O)(H₂O)] _n (2) is a coordination polymer. In this case one acid group of the ligand is deprotonated and 2 form self-assembly by intermolecular hydrogen bonds between the free carboxylic acid groups. The fluoro-substituted ligand 2,2′-(2-fluorophenylmethyledene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H ₂ L _f ) forms disodium salt with a composition [{Na₂L_f(μ-H₂O)(H₂O)₃}·H₂O] _n (3); which is a two dimensional coordination polymer. On the other hand the corresponding cesium salt of H ₂ L _f has a composition [{(H₂O)Cs(μ-H₂O)(μ-L_f)Cs(H₂O)₂}] (4); which is also a 2-D coordination polymer. The cesium ions are six or nine coordinate in the polymer and the coordination polymer possesses unusual Cs···F–C coordination bond.     

Synthesis and characterization of Cu(I) and Zn(II) complexes with new sulfur-bearing isoxazole- or pyrazole-based ligands

The synthesis of the new ligands 6-(5-methyl-1,2-oxazol-3-yl)-2,3-dihydro-5H-[1,4] dithiino[2,3-c]pyrrole-5,7(6H)-dione (isox′) and 6-(3-methyl-1H-pyrazol-5-yl)-2,3-dihydro-5H-[1,4]dithiino[2,3-c]pyrrole-5,7(6H)-dione (pyraz′) and their coordination chemistry toward Cu(I) and Zn(II), was studied. The ligands and their complexes were characterized using a combination of either multinuclear NMR (¹H and ¹³C{¹H}), HRMS, FTIR or Uv–Vis spectroscopy. The solid state structures of ligand isox′ and complexes [Cu(pyraz′)₂]OTf and [Zn(OOCCF₃)₂(pyraz′)₂] were determined. Interestingly, isox′ presents a yellow luminescence in its free form. Additionally, the ability of isox′ to coordinate as an N–O bidentate ligand or as an N–S bridge between two copper centers, forming a coordination polymer, is studied. The solid state structure of this Cu(I)-isox′ 1D coordination polymer is also reported.     

Coordination versatility of 1,5-bis(salicylidene)carbohydrazide in Ni(II) complexes

Versatile coordination behavior of a polydentate Schiff base ligand 1,5-bis(salicylidene)carbohydrazide (H₃bsc) has been explored in Ni(II) complexes. [Ni(H₃bsc)₂](ClO₄)₂ (1)·H₂O·3CH₃CN is a bis chelate mononuclear complex of H₃bsc in keto form, and [Ni₄(H_0.5bsc)₂(O₂CCMe₃)₃(CH₃OH)₄](2)·2H₂O·2CH₃OH is a tetranuclear complex of H₃bsc with an unusual coordination. In 2, one phenolate group of the ligand coordinates in a monodentate way and the other coordinates in a μ₂-bridging mode to the Ni(II) center. This unusual coordination mode of the ligand stabilizes the Ni(II) complex in a tetranuclear form where the carbonyl oxygen of the ligand exists in between keto and enol form of bond order 1.5. Thus, complex 2, represents an unprecedented coordination behavior of the Schiff base ligand derived from carbohydrazides. Studies of magnetic properties of 2 are reported which reveal antiferromagnetic interaction between four Ni(II) centers.     

A Novel Copper(II)–Hydrogen Oxalate Coordination Polymer Showing a New Coordination Mode

A novel Cu(II) coordination polymer of general empirical formula {[Cu(μ-HC₂O₄)₂(H₂O)₂][Cu(HC₂O₄)₂]∙6H₂O} _n (1) has been synthesized and characterized by single-crystal X-ray diffraction technique. The complex (1) crystallizes in the triclinic form with P-1 space group. It is quite surprising that single crystal X-ray analysis of 1 illustrates the presence of hydrogen oxalate ligand in the coordination environment of Cu(II) ion. Because oxalate is not present in the starting reaction mixture, it may be derived from the reduction of squarate ligand. In 1, Cu(II) ions exhibit two different coordination environments, forming a distorted octahedral geometry. The Cu1 is coordinated with six oxygen atoms from two bidentate HC₂O₄ ⁻ and two aqua ligands, while Cu2 is coordinated with six oxygen atoms from four HC₂O₄ ⁻ ligands. The HC₂O₄ ⁻ ligand acts in two different coordination modes, as a bidentate and an unprecedented tridentate bridging coordination mode.     

Extraction of Lanthanides(III), U(VI), and Th(IV) from Nitric Acid Solutions with 1,5-N,N'-Bis[(diphenylphosphoryl)acetylamino]pentanes

Novel polyfunctional neutral organophosphorus ligands, namely 1,5-N,N'-bis[(diphenylphosphoryl)acetyl(alkyl)amino]pentanes [Ph₂P(O)CH₂C(O)NR]₂(CH₂)₅ (Ia, R = C₆H₁₃; Ib, R = CH₃), were studied as extractants for Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, and U from nitric acid solutions. The effect of both HNO₃ 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 was determined by the slope analysis method. Compared with the related bisaminopentane [Ph2P(O)CH₂C(O)NH]₂(CH₂)₅ (Ic), the replacement of hydrogen atoms at the amide nitrogens by alkyl radicals (compounds Ia,b) leads to an increase of metal ions extraction. Bis-CMPO ligands Ia-c were found to possess higher extraction efficiency towards U(VI), Th(IV), and Ln(III) than their monophosphorylated analogue Ph₂P(O)CH₂C(O)N(C₄H₉)₂.