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.     

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 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,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.     

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.     

Assembly, Fluorescence Properties and Antitumor Activity of Novel Silver(I) Cyanide Supramolecular Coordination Polymer Based on Trans-1,2-bis(4-pyridyl)ethene and Me3SnCl

A bimetallic supramolecular coordination polymer; {[(Me₃Sn)₈Ag₄(OH)₄(CN)₈(tbpe)](tbpe)} _n , 1, was obtained by the reaction in situ of K₂[Ag(CN)₂] with Me₃SnCl and trans-1,2-bis(4-pyridyl)ethene (tbpe) in a H₂O/MeCN/NH₃ solvent. The structure of 1 consists of discrete puckered tetranuclear chains comprising {[(Me₃Sn)₄Ag₂(OH)₂(CN)₄]₂(tbpe)} in addition to one template free tbpe ligand. In these chains, the bridging hydroxyl group and the bipodal tbpe ligand are used to give two novel spacers based on the organometallic Me₃Sn unit; i.e., a longer spacer [–CN–(Me₃)Sn–O(H)–(Me₃)Sn–L–(Me₃)Sn–O(H)–(Me₃)Sn–NC–] with a separation distance of 31.29 Å, and a relatively shorter spacer [–CN–(Me₃)Sn–O(H)–(Me₃)Sn–NC–] with a separation distance of 14.431 Å. Supramolecular interactions such as hydrogen bonding, π–π stacking, cation···π interactions, play a prominent role in the assembly of this compound. The structure of the SCP was also investigated by FTIR and electronic absorption spectra and thermal analysis and the data are compared to the prototype compounds. The SCP 1 exhibits strong fluorescence in acetonitrile and shows specific in vitro antitumor activity against human breast cancer cell line, MCF7.     

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.     

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 Novel Bimetallic Chain Based on [Mo(CN)<Subscript>8</Subscript>]<Superscript>3−</Superscript> and Yb<Superscript>3+</Superscript> Ions as Building Blocks in Which Containing Many Intriguing Structural Features

A novel Mo^V–Yb^III bimetallic chain, {[Yb^III(bpy)₂(DMF)(H₂O)][Mo^V(CN)₈]·0.5bpy·4.5H₂O}_n (1) (DMF = N,N′-dimethylformamide; bpy = 2,2′-bipyridine), has been constructed by the reaction of [Mo(CN)₈]³⁻ with Yb³⁺ and 2,2′-bipyridine. Complex 1 is confirmed as a host–guest supramolecular structure by X-ray structural analysis. The neighboring chains interact with each other with two types of hydrogen bonds and two types of π···π interactions. Thus complex 1 has a unique 3D network. Magnetic analysis of 1 indicates the presence of a strong Yb^III single-ion effect owing to spin–orbital coupling within this system.     

A New Metal–Organic ZnII Supramolecular Assembled via Hydrogen Bonds and N···N Interactions as a New Precursor for Preparation Zinc(II) Oxide Nanoparticles, Thermal, Spectroscopic and Structural Studies

A new 1D supramolecular involving two different ligands, {[Zn(GB)₂]·(μ-bpe)₃} _n (ClO₄)_2n ·nH₂O (GB = 2-guanidinobenzimidazole and bpe = 1,2-bis(4-pyridyl)ethylene, has been synthesised, characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy. The thermal stability of compound {[Zn(GB)₂]·(μ-bpe)₃} _n (ClO₄)_2n ·nH₂O was studied by thermal gravimetric and differential thermal analyses. The single crystal X-ray analysis shows that the complex is a one-dimensional polymer involving macrocycle rings as a result of non-covalent bridging bpe ligands via N–H···N and N···N interactions, N–H···bpe···bpe···H–N, with the basic repeating {[Zn(GB)₂](μ-bpe)₃}(ClO₄)₂·H₂O units and by connecting [Zn(GB)₂]²⁺ nodes. ZnO nanoparticles were obtained by calcination of compound {[Zn(GB)₂]·(μ-bpe)₃} _n (ClO₄)_2n ·nH₂O at 500 °C in air. The nanoparticles were characterized by X-ray diffraction and scanning electron microscopy.     

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.     

A novel two-dimensional network self-assembled by the narrowest ladder cations [Cu(CH3COO)(bpe)(H2O)]nn+ containing the Cu2(μ-O)2 cores and the dimeric anions [Cu2(nta)2(bpe)]2− through hydrogen-bonding interaction

A novel complex [Cu(CH₃COO)(bpe)(H₂O)]_n·n/2[Cu₂(nta)₂(bpe)] ·6nH₂O) (bpe=trans-1,2-bis(4-pyridyl)ethylene) was synthesized and characterized. The molecule structure shows that it is composed of the ladder-like double chain cations [Cu(CH₃COO)(bpe)(H₂O)]_nⁿ⁺ and the dimeric anions [Cu₂(nta)₂(bpe)]²⁻. Through bridging oxygen atom of the acetate, the Cu₂ (μ-O)₂ core is formed. The ladder-like chain cation is the narrowest ladder [3.422(3) Å]. Two-dimensional undulating network is constructed by the cations and the dimeric anions through hydrogen-bonding interactions.     

Self-Recognition of 3D Porous Frameworks: Fourfold Diamondoid or Threefold Cuboidal Interpenetrating Nets Formed by Varying Pillar Motifs

Compound [Ni(2,6-ndc)(bpe)(H₂O)] _n (1) was prepared by the hydrothermal reaction of 2,6-naphthalenedicarboxylic acid (2,6-H₂ndc) and trans-1,2-bis(4-pyridyl)ethylene (bpe) with Ni(NO₃)₂·6H₂O under alkaline (NaOH) conditions. Treatment of 2,6-H₂ndc, 4,4′-bipyridine (4,4′-bpy) with M(NO₃)₂·6H₂O (M = Ni or Co) under similar conditions afforded compounds [Ni₂(2,6-ndc)₂(4,4′-bpy)] _n (2) and [Co₂(2,6-ndc)₂(4,4′-bpy)] _n (3), respectively. A single-crystal X-ray diffraction study revealed that compound 1 adopts a 3D fourfold interpenetrating diamondoid network stabilized by inter-net OH···O hydrogen bonds. The anionic 2,6-ndc ligand presents two different bonding characteristics, bis(monodentate) and bis(chelating bidentate) modes. A solid-state structural analysis revealed that compounds 2 and 3 are isomorphous and isostructural. Both present a 3D threefold interpenetrating cuboidal framework, consisting of a 2D (4,4)-net of interconnected [M ₂(O₂C)₄] (M = Ni, Co) paddle-wheel dinuclear units, and pillared by 4,4′-bpy ligands. The degree of interpenetration of these compounds could be adjusted successfully by varying only the organic pillar motifs.     

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.     

One-pot synthesis of two new metal–organic networks: hydrogen bonded mononuclear Cu(II) complex and mixed-valence Cu(I,II) coordination polymer with encapsulated 14-membered unique water cluster

{[Cu₄(μ-bpe)₄Cu₂(μ-pydc)₂(μ₃-pydc)₂]·14H₂O}_n (1) and [Cu(pydcH)₂(bpe)₂] (2) have been solvothermally synthesized by 1,2-bis(4-pyridyl)ethylene (bpe) along with dianionic pyridine-2,3-dicarboxylate (pydc) ligands and characterized by elemental, FT-IR and thermal analyses techniques. In the solvothermal synthesis of complexes, 1 was isolated when the reactor was opened whereas 2 was crystallized after 3 weeks. The X-ray crystallographic studies show that complex 1 exhibits ladder-like structure involving mixed-valence Cu(I,II) which has generated a simultaneous in situ redox reaction and a unique 14-membered water cluster consisting of an eight-membered open-cube hexamer and two cyclic water trimers has been observed in hydrophilic cavities of 1. Supramolecular network of 2, which has proton transfer product of pydcH cations, is formed by O–H···N and aromatic interactions.     

3D-Supramolecular Coordination Polymers as Effective Oxidizing Agents Towards 2,4-Dichlorophenol and 2,6-Di-<Emphasis Type="Italic">t</Emphasis>-butylphenol

3D-supramolecular coordination polymers (SCP) of the type [(R₃Sn)₃Fe^III(CN)₆]; R = CH₃ (I), n-Butyl (II) and phenyl (III) contain wide expandable channels capable of encapsulating and in situ oxidizing 2,4-dichlorophenol (DClP) and 2,6-di-t-butylphenol (DBP) to 2-chloro-1,4-benzoquinone (2-ClBQ) and 3,5,3,5-tertra-t-butyl-4,4-diphenoquinone (BDPQ), respectively, to form new host–guest supramolecular coordination polymers (HGSCP) (1–6). The oxidation products are investigated by spectrophotometry and HPLC methods. A kinetic study indicated a first-order reaction with respect to the hosts SCP I–III. The mechanism and rate of oxidation are discussed in relation to the structure of the SCP.     

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 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.     

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.     

Structural and Magnetic Properties of One-Dimensional Squarate Bridged Coordination Polymers Containing 2-Aminomethylpyridine Ligand

Three novel one-dimensional (1D) coordination polymers with general formula {[M(μ-sq)₂(amp)₂]·H₂O}_n [M=Cu(II) (1), Zn(II) (2)] and [Cd(μ-sq)₂(amp)₂]_n (3) [sq: Squarate; amp:2-aminomethylpyridine] have been prepared and spectroscopically studied. Each metal (II) ion in 1–3 is octahedrally coordinated by two sq and two amp ligands. The amp ligands are N,N′ coordinated, while the sq ligands bridge the metal centers forming 1D linear chain structure. The individual chains are linked by O–H···O hydrogen bonds involving the hydrogens of water molecules (1–2), amino hydrogens and squarate O atoms (1–3). The hydrogen bonded layers are further assembled into three-dimensional supramolecular networks by weak aromatic π–π interactions. EPR results indicate that the ground state of the paramagnetic electron in 1 and Cu²⁺ doped complexes 2–3 is d_{x² - y²} d_{{x^{2} - y^{2} }} . Magnetic measurements reveal that complex 1 shows paramagnetic behavior.