Sonochemical Synthesis and Characterization of the First Flower-Like Cadmium(II) Coordination Compound: New Precursor to Produce Pure Phase Nano-Sized Cadmium(II) Oxide

For the first time the flower-like cadmium(II) coordination compound, [Cd(2,2’-bpy)(ftfa)₂]_n (1), (2,2’-bpy = 2,2’-bipyridine; ftfa = furoyltrifluoroacetonate) is synthesized sonochemically. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. Single crystalline material is obtained using a heat gradient applied to a solution of the reagents. The thermal stability of compound is studied by thermogravimetric and differential thermal analyses. After calcinations of nano-sized 1 at 400 °C, pure phase nano-sized Cd(II) oxide was produced. The average size of the nanoparticles is estimated by the Scherrer equation (diameter ≈ 25 nm). The morphology and size of the prepared Cd(II)O samples are examined by SEM.     

Sonochemical Synthesis of New Nano-Belt One-Dimensional Double-Chain Lead(II) Coordination Polymer; As Precursor for Preparation of PbBr(OH) Nano-Structure

Nano-structure of a new 1D double-chain Pb(II) coordination polymer, [Pb(μ-HPDC)(μ-Br)(H₂O)]_n (1), {H₂PDC = 2,3-pyrazinedicarboxylic acid} was synthesized by a sonochemical method. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. The structure of compound 1 was determined by single crystal X-ray diffraction and consists of 1D double-chain polymeric units. The coordination number in compound 1 is six and each lead atom is coordinated by two oxygen atoms of HPDC⁻, two nitrogen atoms of HPDC⁻ ligands, one bromide atom and one oxygen of H₂O molecule. The thermal stability of compound 1 was studied by thermal gravimetric and differential thermal analyses. Calcination of the nano-belts of compound 1 at 500 °C under air atmospheres yielded nano-sized particles of PbBr(OH) that characterized by scanning electron microscopy and X-ray powder diffraction.     

Cobalt(II), Zinc(II) and Cadmium(II)-Squarate Complexes with N-Methylimidazole

Three M(II)-squarate complexes, [Co(sq)(H₂O)(Nmim)₄] (1), [Zn(μ_1,3-sq)(H₂O)₂ (Nmim)₂] _n (2) and [Cd(μ_1,3-sq)(H₂O)₂(Nmim)₂] _n (3) (sq = squarate, Nmim = N-methylimidazole) have been synthesized and characterized by elemental, spectral (IR and UV–Vis.) and thermal analyses. The molecular structures of the complexes have been investigated by single crystal X-ray diffraction technique. The squarate ligand acts as two different coordination modes as a monodentate (in 1) and bis(monodentate) (O ^1– O ³ ) bridging ligand (in 2, 3). The Co(II) atom has a distorted octahedral geometry with the basal plane comprised of three nitrogen atoms of Nmim ligands and a oxygen atom of squarate ligand. The axial position is occupied by a nitrogen atom of Nmim and one aqua ligand. The crystallographic analysis reveals that the crystal structures of 2 and 3 are one-dimensional linear chain polymers along the c and b axis, respectively. The configuration around each metal(II) ions are distorted octahedral geometry with two nitrogen atoms of trans-Nmim, two aqua ligands and two oxygen atoms of squarate-O¹,O³ ligand. These chains are held together by the C–H···π, π···π and hydrogen-bonding interactions, forming three-dimensional network.     

One- and Two-Dimensional Cadmium(II) Tetracyanonickelate(II) Coordination Polymers With Imidazole and 2-Methylimidazole Ligands

Two novel cyano-bridged heteropolynuclear complexes, [Cd(im)₄Ni(μ-CN)₂(CN)₂] _n (1) and [Cd(mim)₂Ni(μ-CN)₄] _n (2) (im: imidazole and mim: 2-methylimidazole), have been synthesized and characterized. In 1, the trans-directed cyanide ligands of [Ni(CN)₄]²⁻ anions link two [Cd(im)₄]²⁺ units, whereas in 2, all the cyanide groups take part in bonding with two adjacent [Cd(mim)₂]²⁺ units, resulting 1D and 2D coordination polymers, respectively. The coordination environment of the Cd(II) ion described as distorted octahedral geometry, whereas around the Ni(II) centre had square planar geometry in both complexes. The crystals packing of 1 and 2 were a composite of hydrogen bonding, π···π and C–H···Ni interactions.     

Hydrothermal Preparation, Crystal Structures, Spectroscopic and Thermal Analyses of Cadmium(II) and Cobalt(II) Coordination Polymers With Pyridine-2,3-dicarboxylic Acid

Two novel 1D coordination polymers, [M(μ-2,3-pydc)(H₂O)₃]_n (M = Cd for 1 and Co for 2) (2,3-pydcH₂ = pyridine-2,3-dicarboxylic acid) have been hydrothermally synthesized. Both complexes were characterized by elemental analysis and by IR and UV–Vis spectroscopy. Their molecular and crystal structures were determined by X-ray crystal structure analysis and their thermal stability by TGA-DTA methods. Compound 1 crystallizes in the orthorhombic Pca2 space group, while compound 2 crystallizes in the triclinic P−1 space group. Polymeric chains of 1 and 2 are composed of M(II) ions bridged by pyridine-2,3-dicarboxylate ions (2,3-pydc) in N,O,O′ fashion. Distorted octahedral coordination geometry around the metal ions is completed by three water molecules. A wide range of hydrogen bonding (of the O–H···O type) is also present in the crystal structures. These interactions lead to formation of a 3D structure for 1 and 2D network for 2.     

Sonochemical Synthesis of One-Dimensional Nano-structure of Three-Dimensional Cadmium(II) Coordination Polymer

Nano-wires and nano-rods of a new three-dimensional cadmium(II) coordination polymer, {[Cd₃(3-pyc)₄(NCS)₂(H₂O)₄]·2H₂O} _n (1); 3-Hpyc = 3-pyridinecarboxilic acid, were synthesized by a sonochemical method in two different concetrations. The morphology of the nano-structures depend strongly on reactants’ concentration. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction and is a three-dimensional polymer with two types of Cd(II) coordination environments.     

Preparation of Zinc(II) Oxide Nanoparticles from a New Nano-Size Coordination Polymer Constructed from a Polypyridyl Amidic Ligand; Spectroscopic, Photoluminescence and Thermal Analysis Studies

A new zinc(II) coordination polymer, {[Zn(bpcdp)₂(DMF)₄](ClO₄)₂·(H₂O)₂}_n (1) bpcdp = 2,6-bis(4-pyridinecarboxamide)pyridine has been synthesized and characterized by IR, ¹HNMR and ¹³CNMR spectroscopy. The single crystal X-ray data of compound 1 shows the zinc(II) atom has been considered as octahedral with ZnN₂O₄ coordination sphere. Two nitrogen atoms of bpcdp ligand and four oxygen atoms of DMF molecules have occupied coordination sphere around zinc(II) atoms. The prepared zinc(II) coordination polymer grows in three-dimensional network by hydrogen bonding and π–π stacking interaction. The nanostructure of compound 1 were obtained by sonochemical process and studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), IR and NMR spectroscopy. Thermal stabilities of single crystalline and nano-size samples of compound 1 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The ZnO nanoparticles were obtained by direct calcination of compound 1 at 400 °C and by thermolysis in oleic acid at 200 °C. The obtained zinc(II) oxide nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Synthesis and Characterization of a New Nano Lead(II) Two-dimensional Coordination Polymer by Sonochemical Method: A Precursor to Produce Pure Phase Nano-sized Lead(II) Oxide

A new nano-sized lead(II) coordination polymer, {[Pb₂(μ-3-bpdh)(μ-NO₃)₃(NO₃)]_n (1); (3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene)}, was synthesized by a sonochemical method. The structure of 1, which may be considered coordination polymer of lead(II), consists of metallocyclic chains formed by bridging NO₃ ⁻ and 3-bpdh ligands, thereby making a 2D array of Pb(NO₃)₂ and 3-bpdh. The thermal stability of compound was studied by thermogravimetric and differential thermal analyses. The new nano-structure coordination polymer was characterized by powder X-ray diffraction, elemental analysis and IR spectroscopy. The scanning electron microscopy shows the particle size of the 1 prepared by the sonochemical method is about 95 nm. The PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The scanning electron microscopy shows that the size of the PbO particles are ~60 nm.     

Synthesis and Characterization of One-Dimensional Zinc(II) Coordination Polymers as Precursors for Preparation of ZnO Nanoparticles via Thermal Decomposition

Two new Zn(II) coordination polymers from the ligand, 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene (bpdh), with different anions; i.e., [Zn(μ-bpdh)(H₂O)₄](ClO₄)₂·2bpdh (1) and [Zn(μ-bpdh)(H₂O)₄](NO₃)₂·2bpdh (2), were synthesized and characterized by IR spectroscopy, elemental analyses and X-ray crystallography. Compounds 1 and 2 are 1D coordination polymers and the zinc atoms are linked by four oxygen atoms from water molecules and two nitrogen atoms of bpdh ligands. There are two uncoordinated bpdh ligands that, along with the perchlorate or nitrate anions, form hydrogen bonds with water molecules. ZnO nanoparticles were obtained by thermolysis of 1–2 in oleic acid at 280 °C in air. The ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscopy.     

Nanoparticles of a New Potassium(I) Coordination Polymer from Thermal Treatment with Oleic Acid: Syntheses, Characterization, Thermal, Structural and Solution Studies

Nanoparticles of a new potassium two-dimensional coordination polymer, {[K₂(μ₄-L)₂(μ-H₂O)₄]_n·nH₂O} (1), HL = 3-{[(4-nitrophenyl)methylen]amino}benzoic acid} were synthesized from thermal treatment of compound 1 with oleic acid at 523 K. The nanoparticles were characterized by scanning electron microscopy and FT-IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction. The crystal structure of this compound indicates that the coordination number for the potassium ions is seven. A hydrogen bonding network and π-π stacking interactions result in more stability of compound 1 crystal packing. The thermal stability of compound 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The results of stoichiometry studies and formation of compound 1 in MeCN solution were found to be in support of its solid state stoichiometry and show the 1:1 complex formation between the L⁻ and K⁺ ion in MeCN solution.     

One-Dimensional Cobalt(II) and Zinc(II) Succinato Coordination Polymers with Nicotinamide: Synthesis, Structural, Spectroscopic, Fluorescent and Thermal Properties

Cobalt(II) and zinc(II) succinato (suc) coordination polymers with nicotinamide (nia), {[Co(μ-suc)(H₂O)₂(nia)₂] · 2H₂O} _n (1) and {[Zn(μ-suc)(H₂O)₂(nia)₂] · 2H₂O} _n (2) have been synthesized and characterized by elemental analyses, magnetic moments, IR and TG-DTA. Single-crystal X-ray analyses of 1 and 2 reveal that these complexes are isostructural and crystallize in triclinic space group Complexes 1 and 2 are 1-D coordination polymers, in which the metal(II) ions exhibit an octahedral geometry with two suc, two nia and two aqua ligands. The nia ligand is N-bonded, while the suc ligand bridges the metal centers through the carboxylate groups. The 1D chains are further assembled to form 3D networks by strong N–H···O and OW–H···O hydrogen bonds. IR spectra confirm the coordination modes of both suc and nia ligands, while TG-DTA data are in agreement with the crystal structures. Fluorescent analysis in the solid state shows that all complexes display intraligand (π–π*) emissions of nia.     

Direct Synthesis of Cd3OSO4 Nano-particles From a New Three-dimensional Cadmium(II) Coordination Polymer Precursor

A new three-dimensional Cd(II) coordination polymer, {[Cd₃(3-pyc)₄(NCS)₂(H₂O)₄]·2H₂O} _n (1); 3-Hpyc = 3-pyridinecarboxylic acid, was prepared and characterized by elemental analyses and IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction. The structural determination shows that the compound is a new 3D coordination polymer has different environments containing CdO₅NS and CdO₂N₄ units. This polymeric precursor has been used in the preparation of Cd₃OSO₄ nanoparticles by thermolysis in oleic acid. The new nano-structure of Cd₃OSO₄ was characterized by scanning electron microscopy and X-ray powder diffraction. This study demonstrates that coordination polymers may be suitable precursors to the preparation of desirable nanoscale materials.     

Synthesis and Characterization of Zinc(II) Oxide Nanoparticles by Thermal Decomposition of Two Zinc(II) Nitrite Coordination Polymer Precursors

Two zinc(II) coordination polymers, {[Zn(3-bpdb)(NO₂)]·0.5H₂O} _n (1) and [Zn(4-bpdb)(NO₂)₂] _n (2), 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene}, have been synthesized and characterized by elemental analyses and IR spectroscopy. Nanoparticles of zinc(II) oxide have been prepared by thermolyses of two different zinc(II) coordination polymers, 1–2. The nano-materials were characterized by scanning electron microscopy, X-ray powder diffraction and IR spectroscopy. The thermal stability of ZnO nano-particles was studied by thermal gravimetric and differential thermal analysis and showed that there is no loss of weight, which indicates that the products were zinc(II) oxide. This study demonstrates the coordination polymers may be suitable precursors for the preparation of nanoscale materials.     

Cooperative Effect of 3,3′,4,4′-Benzophenonetetracarboxylic Acid and 1,10-Phenanthroline under Solvothermal Conditions to Afford Two Novel Zinc(II) and Cadmium(II) Complexes

Rational self-assembly of a flexible ligand 3,3′,4,4′-benzophenonetetracarboxylic acid and d¹⁰ transition metal salts in the presence of rigid bidentate ligand 1,10-phenanthroline yields two novel helical coordination polymers with different structural motifs; i.e., [Zn(H₂bbtc)(phen)₂ · 2H₂O] _n (1) and [Cd₂(bbtc)(phen)₄ · 2.25H₂O] _n (2) (H₄bbtc = 3,3′,4,4′-benzophenonetetracarboxylic acid, phen = 1,10-phenanthroline), under solvothermal condition. One is hydrogen bonded and π–π stacked together into a network, and the other is a covalently coordinated 3D framework. The coordination polymers were characterized by FT-IR, UV/VIS and fluorescent spectroscopy, single crystal X-ray diffraction, elemental analysis and differential thermal analysis/thermogravimetry (DTA/TG). The most intriguing structural feature is that each complex exhibits novel helical-spaced chains by reason of two different ligands coordinating to the metal centers. Additionally, compounds 1 and 2 showed good fluorescence properties compared to the free ligands.     

Synthesis,Crystal Structures and Fluorescent Properties of Two Bimetallic Coordination Polymers

Two novel 2D and 3D bimetallic Cd^IINi^II coordination polymers, Cd(2Mpz)(H₂O)Ni(CN)₄ (I) (2Mpz: 2-methylpyrazine) and Cd(2Epz)(H₂O)Ni(CN)₄ (II) (2Epz: 2-ethylpyrazine), have been synthesized and characterized by elemental analysis, powder X-ray diffraction, IR spectra, fluorescent spectra, single crystal X-ray diffraction and thermogravimetric analysis. Based on the analysis of structures, it can be found that the Cd(II) ions in the two complexes have the similar octahedral coordination geometry of CdN₅O, which are linked by [Ni(CN)₄]²⁻ units at the equatorial plane to form 2D sheet layers [CdNi(CN)₄] _n . However, it’s noted that the coordination environment of Ni(II) ions and action of ligands are different. All the Ni(II) ions in I are the five-coordinated pentahedron configuration and 2-methylpyrazine acts as a bridging ligand linking the Cd(II) and Ni(II) ions of the adjacent layers, leading to the 3D metal–organic framework. The structure of II indicates all the Ni(II) ions are the four-coordinated square plane and 2-ethylpyrazine is a terminal ligand coordinated to Cd(II) ions, forming the 2D layer structure. Moreover, the two complexes display significant thermal stability and fluorescent properties.     

A New 4-Connected Co(II) Coordination Framework With an Uncommon Two-Fold Interpenetrating Net: Synthesis, Structure and Luminescence Property

The coordination polymer [Co(pbc)₂(H₂O)]_n(Hpbc = 3-Pyrid-4-ylbenzoic acid) was prepared by hydrothermal synthesis and characterized by single-crystal X-ray diffraction, FTIR spectra and element analysis. X-ray diffraction analysis reveals that the pbc⁻ ligands act as diconnectors to link two Co(II) centers and adopt a two coordination mode: μ ₂-N, O and μ ₂-N, O, O to form infinite wavy cobalt-carboxylate chains along the bc plane. Furthermore, compound, [Co(pbc)₂(H₂O)]_n, shows intense photoluminescence at room temperature.     

A Novel Twofold Interpenetrating 2D (3,5)-Connected Cd(II) Coordination Framework with (52.6)(55.64.7) Topology

The self-assembly of 4′-(4-carboxyphenyl)-4,2′:6′4″-terpyridine (HL) with Cd(II) cation afforded one novel twofold interpenetrating 2D coordination polymer, [Cd(L)₂(H₂O)_1.5] _n . In this compound, the Cd(II) atoms as 5-connected nodes are linked by the bridging ligands L acting as both linear connectors and 3-connected nodes to form a novel (3, 5)-connected 2D framework with the (5².6)(5⁵.6⁴.7) topology. Two equivalents of such 2D framework interpenetrate with each other to form a more complicated supramolecular network. Furthermore, fluorescent measurement on the powder sample shows that the complex strongly emits at 399 nm with the excitation of 331 nm.     

A New 2D Cd(II) Grid-like Structure Based on Hetero-Chiral Helical Chains: Synthesis, Crystal Structure, Thermal and Luminescent Properties

A new 2D Cd(II) coordination polymer, [Cd(BBI)₄Cl₂] _n (BBI = 1,1′-(1,4-butanediyl)bis (imidazole)) (1), was synthesized under hydrothermal conditions, and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction crystallography. For complex 1, each Cd(II) ion crystallizes in a [CdN₄Cl₂] six-coordinated slightly distorted octahedral geometry, coordinating to four BBI ligands by Cd–N bonds, completed by two terminal Cl⁻ anions. The characteristic of 2D grid-like layers, from the central Cd(II) ions as knots and BBI ligands as spacers, is the hetero-chiral helical chains of left- and right-hand helixes. Two kinds of π interactions assemble 2D layers into 3D supramolecular architecture in an ···ABC··· packing arrangement. The fluorescent properties were studied in the solid state for its luminescent applications.     

Synthesis and Characterization of ZnS and ZnO Nanoparticles via Thermal Decomposition of Two New Synthesized One-Dimensional Coordination Polymers at Two Different Temperatures

Two new Zn(II) coordination polymers from ligand 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene (bpdh) with different anions, [Zn(μ-bpdh)₂(NCS)₂]_n (1) and [Zn(μ-bpdh)₂(N₃)₂]_n (2) were synthesized and characterized by IR spectroscopy, elemental analyses and X-ray crystallography. The structures of the 1 and 2 may be considered coordination polymers of zinc(II) consisting of metallocyclic chains formed by bridging bpdh ligands, making a one-dimensional array of Zn^II and bpdh in a 1:2 stoichiometry. Different morphologies of ZnS and ZnO nano-particles were obtained by thermolyses of compounds 1–2 in oleic acid at different temperatures under air atmosphere, respectively. The ZnS and ZnO nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

One-Dimensional Coordination Polymer Assembled by Tetraaza Macrocyclic Nickel(II) Complex and trans-1,4-Cyclohexanedicarboxylate ligand

The reaction of [Ni(L)]Cl₂·2H₂O (L = 3.14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) with trans-1,4-cyclohexanedicarboxylic acid (H₂chdc) generates a 1D coordination and 2D hydrogen-bonded polymer {[Ni(L)(chdc)₂]·2H₂O}_n (1). The polymer complex was characterized by X-ray crystallography, spectroscopy and magnetic susceptibility. Each nickel(II) ion has a distorted octahedral coordination environment with the four secondary amines of the macrocycle in which two trans carboxylate anions of the chdc²⁻ ligand have assembled around each nickel center. The electronic spectrum of 1 in the solid state exhibits a high-spin octahedral environment. The magnetic behavior of 1 reveals a weak intramolecular antiferromagnetic interaction with J values of −1.15(2) cm⁻¹.