Syntheses, Structures and Properties of Two Metal–Iodide Polymers Based on a Flexile N-Donor Ligand

Two novel metal–organic frameworks based on 1,3-bis(imidazol-1-ylmethyl)-benzene (m-bix), namely [(Cu₄I₄)(bix)₂] _n (1) and [HgI₂(bix)] _n (2) have been synthesized and characterized by IR, elemental analysis, thermogravimetry, luminescent properties and X-ray crystallography. The structure of compound 1 exhibits a 1D metal–organic chain composed of Cu₄I₄ clusters and m-bix ligands, and such chains are further united together to generate a 3D supramolecular structure through inter-chain π···π interactions. In compound 2, the HgI₂-bix chains interact each other to form a layer structure through π···π interactions, then the layers are extended to 3D supramolecular architecture through intermolecular C–H···π interactions.     

Synthesis,Characterization and Crystal Structure of New Organotin Copper Cyanide Three-Dimensional Supramolecular Coordination Polymer Containing Quinoxaline Molecule

Self assembly of K₃[Cu(CN)₄] with Me₃SnCl and quinoxaline (qox) affords the new organotin ternary adduct _∞³[Cu₂(CN)₃·Me₃Sn·qox], 1, as orange platelet crystals. The supramolecular architecture of 1 consists of [Cu₂(CN)₃]⁻ building blocks connected by the (Me₃Sn)⁺ cations forming infinite corrugated 1D-chains. The chains are bridged by the qox molecules forming 2D-layers containing fused distorted polygons. The layers are interwoven forming 3D-network structure, which are stabilized by close packing effects such as H-bonds as well as Cu···Cu and π–π interactions. IR and mass spectra as well as TGA are investigated.     

Ligand-to-Metal Charge Transfer Resulting in Metalloaromaticity of [<Emphasis Type="Italic">R,R</Emphasis>-Cyclohexyl-1,2-bis(2-Oxidonaphthylideneiminato-<Emphasis Type="Italic">N,N′,O,O′</Emphasis>)]Cu(II): A Scrutinized Structural Investigation

Molecular and crystal structure analysis of a tetradentate ligand-to-metal charge transfer (LMCT) complex, [R,R-cyclohexyl-1,2-bis(2-oxidonaphthylideneiminato-N,N′,O,O′)]Cu(II), are described and characterized by X-ray crystallography and FTIR spectroscopy. The Cu(II) centers are coordinated by four atoms of the donor set [N₂O₂] in a distorted square-planar fashion, which can be attributed to an active electronic delocalization within metallacycles and polychelating property of the pro-ligand. Bond valences of copper centers in four crystallographically independent monomers are slightly distinguished from each other, which is associated with differences in charge delocalization levels of the pro-ligands. Total valence of the copper center is increased with increasing π-electron donation from naphthalene fragments to metallacycles. This charge transfer leads to π···π interactions between metallacycles including imine bridges. In addition, decreases in the centroid–centroid distances of π···π interactions are associated with increased aromatic character of metallacycles. Molecules of the complex are stacked as dimers in the crystal structure formed by π···π interactions and aggregations of these dimeric formations along a-axis are strengthened by C–H···O type H-bonds and C–H···π interactions.     

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.     

Structural Influence of the Ligand Geometry on Construction of Coordination Polymers Formed from Silver(I) Chloride Ribbons and Bipodal Nitrogen Donor Ligands

An assembly of adducts of silver nitrate and KCl and bipodal nitrogen donor ligands, 4,4′-bipyridine (bpy), trans-1,2-bis(4-pyridyl)ethylene (tbpe) or 1,2-bis(4-pyridyl)ethane (bpe), at room temperature affords new supramolecular coordination polymers (SCP), [AgCl·bpy] (1), [(AgCl)₂·tbpe] (2) and [(AgCl)₃·(bpe)₂] (3). X-ray single crystal analyses reveal that 1–3 have 3D-supramolecular networks composed of different types of infinite 1D-ribbons of ladder, 1, and staircase, 2 and 3, structures formed from fused minicyle {Ag₂(μ₃-Cl)₂} motifs, which are bridged by the nitrogen donor ligands to form 2D-layers. The 2D-layers are interconnected by extensive hydrogen bonds and π–π stacking thereby creating 3D-networks. The products are also characterized by IR and electronic absorption spectra. SCP 1–3 display strong fluorescence in the solid state at room temperature.     

Concomitant Crystallization of Copper(II) Sachharinato Complexes with 2-methylpyrazine as a Monomer and an One-dimensional Polymer: Syntheses,Crystal Structures,Spectroscopic and Thermal Properties

The reaction of [Cu(sac)₂(H₂O)₄] · 2H₂O with 2-methylpyrazine (mpyz) leads two complexes, concomitant crystallization of a mononuclear complex [Cu(sac)₂(mpyz)(H₂O)₂] (1) and a polymeric complex [Cu(sac)₂(μ-mpyz)]_n (2). Both complexes have been characterized by elemental analyses, magnetic measurements, FT-IR and ESR, TG-DTA and single-crystal X-ray diffraction analyses. Single-crystal X-ray analyses show that complex 1 consists of discrete molecules in which the copper(II) ions exhibits a square-pyramidal coordination geometry. The individual molecules of 1 are connected into a hydrogen-bonded chain structure, which is further assembled to form a three-dimensional network by π–π stacking interactions. Complex 2 is an 1D coordination polymer in which copper(II) centers are bridged by the mpyz ligand. The chains are further assembled to form two-dimensional frameworks by π–π and C–H···π stacking interactions.     

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.     

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.     

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 and Crystal Structures of Cd(II)-Based 1D Coordination Polymer and Mn(II) Coordination Complex with Mixed N- and O-donor Ligands: [Cd2(4-4′-bpy)2(pa)4]n·0.25(H2O) and [Mn(4-4′-bpy)2(pa)(H2O)3]ClO4·2(H2O)

Two new complexes, [Cd₂(4-4′-bpy)₂(pa)₄] _n ·0.25H₂O (1) (pa = phenylacetate), and [Mn(4-4′-bpy)₂(pa)(H₂O)₃]ClO₄·2H₂O, (2), have been obtained from hydrothermal reaction of Cd(NO₃)₂·4H₂O and Mn(ClO₄)₂·6H₂O with a mixture of the ligands, 2-phenylmalonic acid (2-phmalH₂) and 4-4′-bipyridine (4-4′-bpy). The pa is formed in situ by decarboxylation of phenylmalonic acid. These complexes have been characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric analysis and single-crystal X-Ray diffraction. The Cd(II) center is seven-coordinate and linked via pa ligands to form a binuclear complex in the asymmetric unit of 1. A ladder-like 1D chain of binuclear units is formed by Cd(II)–N coordination bond through 4-4′-bpy ligands. Complex 2 consists of a mononuclear manganese center based on a distorted octahedral geometry and exhibits a supramolecular structure containing hydrogen bonds and extensive π···π and C–H···π interactions.     

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.     

A Mixed Valence Copper Cyanide 3D-supramolecular Coordination Polymer Containing 1,10-Phenathorline Ligand as a Potential Antitumor Agent, Effective Catalyst and Luminescent Material

The structure of the 3D-supramolecular coordination polymer (SCP) _∞³{[Cu^Ι(CN)·2(phen)·Cu^ΙΙ(CN)₂·(phen)]·5H₂O}, 1 contains the [Cu^Ι(CN)·2(phen)], [Cu^ΙΙ(CN)₂·(phen)] molecular complexes and five water molecules which are connected with each other by hydrogen bonds. The most intriguing feature in the structure of 1 is the unusual supramolecular interactions, including hydrogen bonds which involve the terminal cyanide and the phenanthroline (phen) ligands and π–π stacking which generate a unique 3D-supramolecular architecture in the solid state. The emission spectrum of 1 displays a band centered at 420 nm which was assigned to S_o-T transition in the CuCN fragments. This band suffers a shift to longer wavelength by about 30 nm than that of CuCN itself. The emission bands at 435, 450, and 475 correspond to the close laying π–π* transitions of the coordinated phen. The main band at 435 nm exhibits a red shift than that of phen by about 70 nm which makes it attractive as luminescent sensor. Also, the SCP 1 was used as heterogeneous catalyst for the degradation of Metanil Yellow (MY) dye by dilute solution of hydrogen peroxide as oxidant. The reaction is first order with respect to the MY dye. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the in vitro antitumor activity of the SCP 1 on human breast cancer cell line, MCF7. The cytotoxicity of the SCP 1 is more efficient than that of the Doxorubicin (DOX) drug. The thermal stability has been also investigated.     

Metal-Organic Framework Constructed by Copper(I) Cyanide and Ethyl Isonicotinate Through Hydrogen Bonding

The reaction of K₃[Cu(CN)₄] and ethyl isonicotinate (EIN) in the presence of Me₃SnCl in H₂O/acetonitrile medium at room temperature affords the 3D-supramolecular coordination polymer (SCP), ∞ ³[CuCN·(EIN)], 1. The structure of 1 consists of 1D-zig-zag chains, which extend via the EIN ligands through hydrogen bonds organized in AB 2D-layers. The infinite AB···AB layers are further extended to form a 3D-network via hydrogen bonds and π–π stacking interactions, thus creating wide channels. The emission spectrum of 1 in the solid state reveals a set of high energy and low energy distinct peaks in the visible region at 400–580 nm upon excitation at 280 nm. The luminescence excitation in 1 could be caused by different possible transitions including metal-to-ligand charge transfer (MLCT) or single-metal-centered (MC) transitions.     

Synthesis, Supramolecular Architecture and DNA Binding Studies of a Novel Heterotrinuclear FeIII/CoII/FeIII Complex: [Co(phen)2][Fe(phen)(CN)4]2·4H2O (phen?=?1,10-phenanthroline)

A novel cyano-bridged heterotrinuclear Fe^III/Co^II/Fe^III complex, [Co(phen)₂][Fe(phen)(CN)₄]₂·4H₂O (1) (phen = 1,10-phenanthroline), has been synthesized under solvothermal conditions, and characterized by elemental analysis, FI-IR spectrum and single-crystal X-ray diffraction. The structure analysis reveals complex 1 is constructed into a 3D supramolecular architecture through abundant intermolecular non-covalent interactions. According to the supramolecular self-assembly of complex 1, five types of π–π stacking models of phenanthroline ligands, hydrogen bonds formed by four lattice water molecules, and C–H···N weak interactions involving cyano groups are all observed. Electronic absorption spectroscopy and fluorescence titration studies of the interaction between complex 1 and calf thymus DNA are suggestive of an intercalative binding mode with an intrinsic binding constant of 7.95 × 10³ M⁻¹ and a linear Stern–Volmer quenching constant of 1.033 × 10⁵ M⁻¹.     

Hydrothermal Synthesis of Metal–Organic Coordination Polymers Constructed from Asymmetric Semi-rigid V-shaped Dicarboxylate and Nitrogen-Contained Mixed Ligands

Three new coordination polymers, [Ni(2,4′-oba)(1,10-phen)] _n (1), {[Ni (2,4′-Hoba)₂(4,4′-bipy)(H₂O)₂]·2H₂O} _n (2) and [Zn(2,4′-oba) (4,4′-bipy)] _n (3) (2,4′-H₂oba = 2-(4-carboxyphenoxy)benzoic acid, 1,10- phen = 1,10-phenanthroline, and 4,4′-bipy = 4,4′-bipyridine) have been obtained by hydrothermal synthesis. The framework structures of these polymeric complexes have been determined by single-crystal X-ray diffraction studies. Complex 1 exhibits double-helical chains formed by π–π stacking interactions from the phenyl rings of the 1,10-phen ligands. Complex 2 forms a two-dimensional supramolecular architecture directed by hydrogen bonding. Complex 3 exhibits a three-dimensional structure; Schl?fli symbol of {4⁴·6¹⁰·8}. The luminescent property of compound 3 is discussed.     

Catalytic, Luminescence Activities and Structure of Metal-Organic Frameworks Containing CuCN Building Blocks and Bipodal Bridging Ligands

The reactions of K₃[Cu(CN)₄], R₃SnCl and bipodal ligands, where R = (n-Bu)₃SnCl and L = quinoxaline (qox) and R = Me₃SnCl and L = quinazoline (qaz) afford the red needle crystals of _￥³ [ \textCu₂ ( \textCN )₂ m\text-(qox) ]₂ {}_{\infty }^{3} \left[ {{\text{Cu}}_{2} \left( {\text{CN}} \right)_{2} \mu {\text{-(qox)}}} \right]_{2} , 1 and the orange needle crystals of [Cu₂(CN)₂μ(qaz)]_n, 2. 1 was subjected to single crystals X-ray study while 2 was investigated by IR, ¹H NMR and mass spectra as well as TGA. The crystal structure of 1 exhibits puckered CuCN chains connected by qox molecules forming 2D-sheets. The 2D-sheets contain hexagonal nets stacked in A···A···A fashion. The paralleled sheets are close packed via extensive H-bonds, π–π stacking, strong Cu-Cu interaction and short Cu–C contacts which develop 3D-network. Unique rhombic [Cu₂(μ₃-CN)₂] motifs result as consequence of interwoven of the 2D-sheets. The structure of 2 exhibits different XRPD pattern than that of 1 although, the two structures have the same Cu:CN:L stoichiometric ratio. The emission spectra of 1 and 2 display bands around 390, 420 and 475 nm corresponding to MC transition, ¹(n,π*) → S_o and MLCT, respectively. Thus, 1 and 2 can be considered as examples of room-temperature luminescent Cu-containing polymers which can be used in applications as molecular sensing systems. Also, the oxidative degradation of Metanil Yellow (MY) dye has been investigated by hydrogen peroxide catalyzed by 1 or 2. The catalytic activity of 1 is more pronounced than that of 2.     

A New Nitrosyl-bridged Bimetallic Nitroprusside Complex: Synthesis,Crystal Structure,Supramolecular Self-assembly and Spectral Behavior of Interactions with DNA

A new nitrosyl-bridged bimetallic nitroprusside complex, [Ba(phen)₃(H₂O)][Fe(CN)₅NO]·1.5phen·2H₂O (phen = 1,10-phenanthroline) (1), has been synthesized and characterized by elemental analysis and single crystal X-ray diffraction. The crystal structure analysis reveals that complex 1 crystallizes in the triclinic space group Pī. The asymmetric structural unit is comprised of one [Ba(phen)₃(H₂O)]²⁺ complex cation, one [Fe(CN)₅NO]^2– complex anion, 1.5-uncoordinated phenanthroline molecules and two lattice water molecules. The complex ions are linked into a 1D chain-like arrangement by the trans CN and NO groups in nitroprusside. The six-coordinated Fe-atom forms a distorted octahedral coordination configuration, and the Ba-atom has a nine-coordinate monocapped antiprismatic geometry. Five types of π–π stacking interactions of phenanthroline and some intra- and intermolecular hydrogen bonds are observed in the 3D supramolecular self-assembly. Absorption spectroscopy, fluorescence titration and viscometry studies of the interaction between complex 1 and calf thymus DNA indicate that complex 1 is a moderate metallo-intercalator with the intrinsic binding constant of 3.70 × 10⁴ M⁻¹ and the linear Stern–Volmer quenching constant of 5.98 × 10⁴ M⁻¹.     

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.     

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.     

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.