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-Dimensional Hydrogen-Bonded Polymer from Hexaazamacrotetracyclic Nickel(II) Complex and trans-1,4-Cyclohexanedicarboxylate Ligand

The reaction of [Ni(L)](ClO₄)₂·2H₂O (L) = 1,3,10,12,16,19-hexaazatetracyclo[17,3,1,1^12.16,0^4.9]tetracosane) with trans-1,4-cyclohexanedicarboxylic acid (H₂-chdc) produces a 1D hydrogen-bonded polymer with formula [Ni(L)(H-chdc⁻)₂] (1). This polymer complex has been characterized by X-ray crystallography, spectroscopy and magnetic susceptibility. The crystal structure of 1 shows a distorted octahedral coordination geometry about Ni with two secondary and two tertiary amines of the macrocycle and two oxygen atoms of the H-chdc⁻ ligand at the trans position. Electronic spectrum of 1 exhibits a high-spin octahedral environment. The magnetic behavior of 1 reveals a very weak antiferromagnetic interaction with J values of −0.66(2) cm⁻¹ .     

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.     

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.     

New Binuclear Complexes with Mixed Ligands and μ<Subscript>2</Subscript>-Phenol Oxygen Bridges: Synthesis Crystal Structures and Magnetism

Two new complexes, [M₂(L)₂(bpy)₂](ClO₄)₂ [L = methyl salicylate, bpy = 2,2′-bipyridine, M = Cu (1) and Zn (2)] have been synthesized and structurally characterized by X-ray structure analyses. The centrosymmetric dimeric structure consists of a binuclear unit, in which M (M = Cu or Zn) atoms are bridged by two phenol oxygen atoms as a μ ₂-bridged. The neighboring binuclear units interact with each other by two kinds of weak contacts: one kind is π–π stacking by π–σ attraction with an edge-to-face C–H···π interaction, and the second type is a H-bonding interaction, which extends the binuclear unit into a 3D network. Magnetic measurements confirm that 1 presents a very strong intradinuclear ferromagnetic coupling between the copper(II) ions.     

Syntheses and Characterizations of Three Cu(II) Complexes with 2,2′-Bipyridine-3,3′-dicarboxylate and <Emphasis Type="Italic">N</Emphasis>-Donor Ancillary Ligands

Abstract  

Three novel inorganic–organic hybrid frameworks of [Cu(BPDC)(2,2′-bipy)] (1), [Cu(BPDC)(BIB)₂ ·H₂O]_n (2) and [Cu(BPDC)(4,4′-bipy)]_n (3) (BPDC²⁻ = 2,2′-bipyridine-3,3′-dicarboxylate; 2,2′-bipy = 2,2′-bipyridine; BIB = 1,2-bis(imidazol-1-ylmethyl)benzene; 4,4′-bipy = 4,4′-bipyridine) were prepared. The three complexes have been characterized by the elemental analyses, IR spectra, TGA and the single crystal X-ray diffraction. Two intramolecular Cu(II) centers of 1 are encircled by two BPDC²⁻ ligands forming an 18-membered ring, which is further assembled into a three-dimensional (3D) supramolecular architecture through the C–H···O hydrogen-bonding interactions. Complex 2 possesses a two-dimensional layer network, while complex 3 is a three-dimensional polymer composed of Cu-BPDC helical chains bridged by 4,4′-bipy. In addition, the electrochemistry of complex 1 was investigated.     

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.     

One Dimensional Coordination Polymer of Nickel(II)-Squarate with N,N,N′,N′-tetramethylethylenediamine, {[Ni(μ-sq)(H2O)2(tmen)]·H2O}n

A novel 1D coordination polymer {[Ni(μ-sq)(H₂O)₂(tmen)]·H₂O}_n (H₂sq = squaric acid and tmen = N,N,N′,N′ -tetramethylethylenediamine) has been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV-vis.) and magnetic susceptibility are reported. The structure of the complex consists of the bidentate tmen ligand bound to Ni(II) center and a bridging squarate in the 1,3-bonding mode. The distorted octahedral geometry of Ni(II) is completed by two aqua ligands. The structure contains chains of squarato-O ¹ ,O ³ -bridged polynuclear nickel(II) units held together by intermolecular hydrogen bonds interactions between water molecules and oxygen atoms of squarate ligand forming a novel R6 motif.     

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.     

Metal(II) Nicotinamide Complexes Containing Succinato,Succinate and Succinic Acid: Synthesis,Crystal Structures,Magnetic, Thermal,Antimicrobial and Fluorescent Properties

Four novel divalent transitional metal succinates (suc) with nicotinamide (nia), {[M(μ-suc)(H₂O)₂(nia)₂]·2H₂O} _n [M = Mn (1), Ni (2)], [Cu(suc)(nia)₂] (3) and [Ni(H₂O)₄(nia)₂](suc)·(H₂suc) (4), have been synthesized and characterized by elemental analyses, IR and TG-DTA. X-ray analyses of 2 and 4 reveal that they crystallize in a triclinic space group P[`1]. P\bar{1}. Complex 2 is a 1-D coordination polymer, 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 centres through the carboxylate groups. 4 contains the [Ni(H₂O)₄(nia)₂]²⁺ complex cations, uncoordinated suc and H₂suc species, which are connected into a two-dimensional layered structure by the combination of N–H⋯O and OW–H⋯O hydrogen bonds. This is one of the scarce examples encountered in coordination chemistry, which contains uncoordinated suc and H₂suc at the same time. The spectroscopic and structural analysis, luminescent and magnetic properties and the antimicrobial activities of the synthesized complexes were investigated.     

Solvent Control Over Structural Diversity of Two Copper (II) Complexes Based on Polyaromatic Acid Ligand

Abstract  

A new bipod polyaromatic acid ligand H₂bcm (H₂bcm = {2, 4-bis [(2′-carboxyphenoxy) methyl]-1,3,5-trimethylbenzene}) is prepared and its two novel binuclear coordination compounds, [Cu₂(bcm)₂(CH₃OH)₂]·2CH₃OH (1) and [Cu₂(bcm)₂(CH₃CH₂OH)₂]·2CH₃CH₂OH (2), have been synthesized with copper acetate and H₂bcm ligand in methanol solvent and ethanol solvent respectively, and characterized by the element analysis, IR, TGA and single crystal X-ray diffraction. The results of structural analysis indicate that 1 crystallizes in the triclinic system with space group P1, while 2 crystallizes in the monoclinic system with space group P2₁ /c. Furthermore, 1 adopts μ ₂ -COO⁻ and syn–syn coordination mode with Cu (II)···Cu (II) separation of 2.5868(11) ? and forms 1D zigzag chain structure by O···O interactions. The coordination of 2 is similar to that of 1 except that ethanol molecules are coordinated instead of methanol molecules with Cu (II)···Cu (II) separation of 2.5973(13) ?. Two-dimensional network structures of 1 and 2 are formed through π–π interactions.     

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.     

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.     

Hydrothermal Synthesis, Characterization of Mn(II) and Cd(II) Coordination Polymers Assembled from Semi-Rigid Oxo-Bridged Carboxylate and N-Donor Ligands

Two new metal–organic coordination polymers containing Mn(II) and Cd(II) with oxo-bridged and N-donor ligands, [Mn(oba)(2,2′-bipy)] _n (1) and {[Cd(oba)(bib)]·H₂O} _n (2) [2,3′-H₂oba = 2-(3-carboxyphenoxy)benzoic acid, 2,2′-bipy = 2,2′-bipyridine, and bib = 4,4′-bis(2-methylimidazole-1-ylmethyl)biphenyl], have been prepared and characterized by elemental analysis, Fourier infrared spectroscopy, and X-ray diffraction. Complex 1 has a 3D supramolecular network constructed from 1D zigzag chain via π–π stacking interactions. Complex 2 features 1D ladder-like chain which consists of 1D helical arrays and bib pillars. Moreover, photoluminescence properties of the bib ligand and the Cd(II) complex were investigated.     

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.     

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.     

Synthesis, Characterization and Crystal Structure of a Novel Three-Dimensional Supramolecular Framework Containing Ni···π Interaction Heteronuclear Complex: {[Cu(4(5)-Meim)4][Ni(CN)4] · H2O}n

The heteronuclear complex, {[Cu(4(5)-Meim)₄][Ni(CN)₄] · H₂O}_n (1), (4(5)-Meim = 4(5)-methylimidazole) was synthesized and characterized by FT-IR spectroscopy, single crystal X-ray diffraction, thermal analysis and elemental analysis. The Cu(II) ion has a distorted square planar geometry, extended to (4 + 2) weak coordination by two nitrogen atoms of the cyano group. The coordination sphere around the Ni(II) ion should be described as a 4 + 2 geometry with the four cyano groups and the axial coordination site is located at the imidazole ring though a weak Ni···π interaction. The coordination bond is much stronger than the Ni···π interactions and it is expected that the formation of the coordination bond will affect more significantly the position of the absorption bands associated with the vibrations of the ligand. In addition, the out-of-plane modes of 4(5)-Meim are shifted to higher frequencies relative to free ligand. We propose that these shifts are indicative of the weak CH∙∙∙π and Ni∙∙∙π interactions, according to the crystallographic and spectroscopic data.     

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 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.     

Syntheses, Structures, and Luminescent Properties of Two Novel Coordination Polymers with Mixed Ligands

Two novel metal–organic coordination polymers {[Pb₂(MIP)₂(BDC)₂]·H₂O} _n 1 and [Cd(MIP)(NDC)] _n 2 [MIP = 2-(3-methoxyphenyl)-1H-imidazo [4,5-f] [1, 10] phenanthroline, BDC = terephthalic acid, NDC = naphthalene-1,4-dicarboxylic acid] were obtained from hydrothermal reaction and characterized by elemental analysis, thermogravimetric (TG) analysis, infrared spectrum (IR) and single-crystal X-ray diffraction. The coordination polymers crystallize in triclinic, space group P-1 with a = 1.0335(2), b = 1.4224(3), c = 1.8156(4) nm, β = 106.088(3)° for complex 1 and the complex 2 crystallizes in monoclinic, space group P2(1)/n with a = 1.2562(8), b = 1.4800(9), c = 1.3723(8) nm, β = 97.257(1)°, respectively. The metal ions Pb(II) are located in [:PbN2O4] pentagonal bipyramidal geometry in complex 1. The metal ions Cd(II) in complex 2 act as distorted octahedral geometry, being surrounded by four carboxylate oxygen atoms from three NDC ligands and two donor nitrogen atoms from one MIP molecule. Moreover, there are hydrogen bonds in the two complexes, and it is noteworthy that the existence of hydrogen bonds and π–π interactions reinforce the structural stability of the title complexes, which have been proved by TG analysis. The luminescent properties for the ligand MIP, NDC and complex 2 are also discussed in detail.