Metal-organic Hybrid Compound Research Articles

Poly[bis-(μ2-N,N-di-methyl-formamide-κ2 O:O)bis-(μ4-thio-phene-2,5-di-carboxyl-ato-κ4 O:O':O'':O''')dicobalt(II)

The asymmetric unit of the title three-dimensional metal-organic hybrid compound, [Co2(C6H2O4S)2(C3H7NO)2] n , comprises two cobalt(II) cations, one residing on a twofold axis and the other on a centre of inversion, one thio-phene-2,5-di-carboxyl-ate (tdc2-) ligand and one coordinating di-methyl-formamide (DMF) solvent mol-ecule. Both of the cobalt(II) cations exhibit an octa-hedral coordination environment from the four carboxyl O atoms of the tdc2- anions in a μ 4-κ 1:κ 1:κ 1:κ 1 fashion and two O atoms from DMF. A pair of carboxyl O atoms and one DMF molecule connect the adjacent cobalt(II) cations into an infinite chain, leading to a rod-spacer framework with rhombus-window channels, yet no residual solvent-accessible voids are present because the coordinating DMF molecules are oriented into the potential channels.

Two new crystal structures of two-dimensional lead(II) coordination polymers with flexible alicyclic carboxylate ligands

ABSTRACTTwo new coordination polymers with flexible alicyclic carboxylate ligands, generally formulated as [Pb(chda)]n (1, H2chda = 1,1′-cyclohexanediacetic acid) and [Pb(tmg)]n (2, H2tmg = 3,3′-tetramethyleneglutate), have been successfully synthesized through the liquid–liquid diffusion method. They represent the first main group of metal–organic hybrid compounds assembled from H2chda and H2tmg. Compound 1 crystallized in the non-centrosymmetric space group Pca21, whereas 2 adopts the centrosymmetric P2(1)/c space group. Their structure features one-dimensional infinite chains extended into two-dimensional layer framework. Interestingly, the lead atoms exhibit hemi- as well as holo-directed coordination geometry with coordination number seven in both compounds.

Methanol-Influenced Assembly of Metal–Organic Hybrid Compounds Based on Propane-1,3-diamine Ligands and [XCl4]2– (X = Zn, Hg)

The authors designed two flexible ligand molecules, namely, (N1,N1,N3,N3-tetrakis(4-methylbenzyl)propane-1,3-diamine) (L1) and (N1,N1,N3,N3-tetrabenzylpropane-1,3-diamine) (L2), with (CH2)3 alkyl chains attached to the two N atoms. The ligands are double protonated and can react with tetrachloride metal dianion [XCl4]2– (X = Zn, Hg) in the presence of methanol solvent, leading to a series of new inclusion complexes, (CH3OH)2 ⊂ [L1]2H+· [ZnCl4]2–(crystal 1), (CH3OH)0.5 ⊂ [L2]2H+·[HgCl4]2 (crystal 2), and CH3OH ⊂ {[L2]2H+}0.5· {[ZnCl4]2–}0.5 (crystal 3). The molar ratios of methanol and ligand are 2:1, 1:2, and 2:1 in the three crystals, respectively. The structures were characterized by NMR and single-crystal X-ray diffractions. The effect of guest methanol molecules on the formation of supramolecular assemblies was discussed. The ligand can adopt different molecular arrangements as so to suit for the demands of same guest species. From the structural view point, we showed the relationship between the diversity of inclusion hosts and conformational flexibility of ligand.

A Mononuclear CoII Coordination Complex Locked in a Confined Space and Acting as an Electrochemical Water‐Oxidation Catalyst: A “Ship‐in‐a‐Bottle” Approach

AbstractPreparing efficient and robust water oxidation catalyst (WOC) with inexpensive materials remains a crucial challenge in artificial photosynthesis and for renewable energy. Existing heterogeneous WOCs are mostly metal oxides/hydroxides immobilized on solid supports. Herein we report a newly synthesized and structurally characterized metal–organic hybrid compound [{Co3(μ3‐OH)(BTB)2(dpe)2} {Co(H2O)4(DMF)2}0.5]n⋅n H2O (Co‐WOC‐1) as an effective and stable water‐oxidation electrocatalyst in an alkaline medium. In the crystal structure of Co‐WOC‐1, a mononuclear CoII complex {Co(H2O)4(DMF)2}2+ is encapsulated in the void space of a 3D framework structure and this translationally rigid complex cation is responsible for a remarkable electrocatalytic WO activity, with a catalytic turnover frequency (TOF) of 0.05 s−1 at an overpotential of 390 mV (vs. NHE) in 0.1 m KOH along with prolonged stability. This host–guest system can be described as a “ship‐in‐a‐bottle”, and is a new class of heterogeneous WOC.

A Mononuclear Co(II) Coordination Complex Locked in a Confined Space and Acting as an Electrochemical Water-Oxidation Catalyst: A "Ship-in-a-Bottle" Approach.

Preparing efficient and robust water oxidation catalyst (WOC) with inexpensive materials remains a crucial challenge in artificial photosynthesis and for renewable energy. Existing heterogeneous WOCs are mostly metal oxides/hydroxides immobilized on solid supports. Herein we report a newly synthesized and structurally characterized metal-organic hybrid compound [{Co3 (μ3 -OH)(BTB)2(dpe)2} {Co(H2O)4(DMF)2}0.5]n ⋅n H2O(Co-WOC-1) as an effective and stable water-oxidation electrocatalyst in an alkaline medium. In the crystal structure of Co-WOC-1, a mononuclear Co(II) complex {Co(H2O)4(DMF)2}(2+) is encapsulated in the void space of a 3D framework structure and this translationally rigid complex cation is responsible for a remarkable electrocatalytic WO activity, with a catalytic turnover frequency (TOF) of 0.05 s(-1) at an overpotential of 390 mV (vs. NHE) in 0.1 m KOH along with prolonged stability. This host-guest system can be described as a "ship-in-a-bottle", and is a new class of heterogeneous WOC.

Surprising coordination for low-valent actinides resembling uranyl(vi) in thorium(iv) organic hybrid layered and framework structures based on a graphene-like (6,3) sheet topology.

Three thorium(iv)-based metal-organic hybrid compounds with 2D layered and 3D framework structures exhibiting graphene-like (6,3) sheet topologies were prepared with linkers with threefold symmetry. These compounds contain rare and relatively anisotropic coordination environments for low-valent actinides that are similar to those often observed for high-valent actinide ions.

Syntheses and Structures of Three Divalent Zn/Cd Metal–Organic Supramolecular Frameworks Constructed by 1, 2, 4-benzenetricarboxylate

Three novel metal–organic hybrid compounds, [Zn(H2btc)2(H2O)2]·2H2O (1),[Cd(Hbtc) (H2O)]n (2) and [Zn3(btc)2(phen)2(H2O)2]n (3) (H3btc = 1,2,4- benzenetricarboxylate, phen = 1,10-phenanthroline), have been hydrothermally synthesized and their structures were determined by single-crystal X-ray diffraction. The structural motifs are multiforms from 0D, 3D, and 2D interpenetrating networks. It is found that the H3btc ligand exhibits multicoordinated modes. In these complexes, the carboxylates of btc and water molecules are involved in intermolecular hydrogen bondings to form the 3D molecular frameworks and reinforce the structural stability, which proves that noncovalent interactions like H-bond play an important role in instructing the supramolecular architectures.

Copper(II) perrhenate Cu(C3H7OH)2(ReO4)2: Synthesis from isopropanol and CuReO4, structure and properties

The crystal structure of Cu+Re7+O4 is capable of a quasi-reversible incorporation of C3H7OH molecules. A room-temperature reaction between CuReO4 and C3H7OH under oxidizing conditions leads to the formation of a novel metal-organic hybrid compound Cu2+(C3H7OH)2(ReO4)2. Upon heating under reducing conditions, this compound transforms back into CuReO4, albeit with ReO2 and metallic Cu as by-products. The crystal structure of Cu(C3H7OH)2(ReO4)2 solved from single-crystal X-ray diffraction (Pbca, a=10.005(3)Å, b=7.833(2)Å, and c=19.180(5)Å) reveals layers of corner-sharing CuO6-octahedra and ReO4-tetrahedra, whereas isopropyl groups are attached to both sides of these layers, thus providing additional connections within the layers through hydrogen bonds. Cu(C3H7OH)2(ReO4)2 is paramagnetic down to 4K because the spatial arrangement of the Cu2+ half-filled orbitals prevents magnetic superexchange. The paramagnetic effective moment of 2.0(1) μB is slightly above the spin-only value and typical for Cu2+ ions.

Preparation and properties investigation of a new metal-organic hybrid compound with reversible structural phase transition: bispyrrolidinium tetrachlorozincate

A new metal-organic hybrid compound(1) with stuctural phase transition above room temprature has been synthesized. Differential scanning calorimetry(DSC) measurement shows a pair of reversible thermodynamics peaks at 320.5 K(cooling) and 339.5 K(heating) with a large heat hysteresis about 19 K, indicating the compound undergoes a reversible structural phase transition. Dielectric measurement with a step-like dielectric anomaly further confirms the phase transition. The crystal structures of 1, determined at 150 K and 353 K, are both monoclinic in P21/c, suggesting the phase transition is isosymmetric. Temperature-dependent single crystal analyses of 1 reveal that the displacement of zinc atom is mainly responsible for the reversible structural phase transition.

Structural studies and conductivity of [Fe(O<sub>3</sub>C<sub>4</sub>)(COO)]·H<sub>2</sub>O based H<sub>4</sub>btec (H<sub>4</sub>btec = 1,2,4,5-benzenetetracarboxylic acid)

A new metal-organic hybrid compound [Fe(O3C4)(COO)]·H2O I has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Rust crystals crystallize in the monoclinic system, space group I2/a, a = 6.9651(2) A, b = 8.12630(10) A, c = 19.4245(2) A, β = 92.6600(10)°; V = 1098.25(4) A3; Z = 2 and Dx =3.63g/cm3. The refinement converged into R = 0.042; Rw = 0.058. The structure, determined by single crystal X-ray diffraction, consists of a network of FeO6 centers, octahedral coordinated by btec (btec = 1,2,4,5-benzenetetracarboxylic acid) anions giving rise to a two-dimensional sheet structure. In the compound I, [Fe(O3C4)(COO)]·H2O, the FeO6 group bridged by the 1,2,4,5-benzenetetracarboxyl anion exist in a unit cell, with each anion lying about an inversion centre. One of the FeO2 adistance [1.965(2)] significantly corresponds to the shortest distance as the other and the distances found in the axial direction of compound I.

PH-dependent assembly of metal–organic hybrid compounds based on octamolybdates and a new flexible multidentate ligand

Six novel molybdenum hybrid materials based on a flexible multidentate ligand, namely (H3tib)4(β-Mo8O26)3·5H2O (1), (H3tib)2[Cu(H2O)2(γ-Mo8O26)2]·2H2O (2), [Cu(Htib)2(δ-Mo8O26)]·4H2O (3), [Cu2(tib)2(H2O)2(γ-Mo8O26)]·H2O (4), (H3tib)2[Co(H2O)2(γ-Mo8O26)2]·2H2O (5), and Zn(tib)(MoO4)·3H2O (6) (where tib = 1,3,5-tris(imidazol-1-ylmethyl)benzene), have been synthesized at different pH values under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by PXRD, TGA, IR spectra, and electrochemistry. Compound 1 is a supramolecule with classical β-Mo8O26 cages. Compounds 2 and 5 exhibit a rare one-dimensional (1D) molybdenum oxide duplex chain. We have not yet found any other examples of the two adjacent 1D molybdenum oxide chains linked together through the centers of the Cu/Co cations. In 3, the CuII cations are bridged by Htib+ ligands and (δ-Mo8O26)4− anions to form an interesting two-dimensional (2D) layer. In 4, the CuIIcations, tib ligands and (γ-Mo8O26)4− anions are connected to form a 2D layer, which is further reinforced by the tib ligands through an Mo–N bond. Compound 6 is a 2D coordination polymer possessing a high thermal stability. The structural diversities of 2–4 reveal that the pH value of the reaction system, the metal coordination preference and the ligand configuration play a crucial role in the assembly of POM-based complexes.

Enhanced Magnetic Hardness in a Nanoscale Metal-Organic Hybrid Ferrimagnet

A new layered metal-organic hybrid compound, namely, [Co(3)(μ(3 -OH)(2)(BTP)(2)] (1; BTP=4-(3-bromothienyl)phosphonate), is reported. The inorganic layer can be viewed as a pseudo-Kagomé lattice composed of corner-sharing irregular triangles of Co(3) (μ(3)-OH), with the cavities filled with the PO(3) groups. The interlayer space is occupied by the 3-bromothienyl groups of BTP(2-). The bulk sample of compound 1 experiences a long-range ferromagnetic ordering below 30.5 K, with a coercivity (H(c)) of 5.04 kOe at 5 K. A systematic study on the size-dependent magnetic coercivity of 1 reveals that the coercivity of 1 increases with reduced particle size from the micrometer to the nanometer scale. When the particle size is about 50-200 nm, the coercivity reaches 24.2 kOe at 5 K. The results demonstrate that compound 1 can vary from a soft magnet to one of the hardest molecule-based magnets, simply by reducing the particle size to nanoscale region.

A novel molybdenum-oxide-based metal–organic hybrid compound with 3-fold interpenetrated topology

A novel complex {[Cu 12 (4,4´-bpz) 12 (H 2 Mo 8 O 28 ) 3/2 (Mo 8 O 26 ) 3/2 ]·3(H 3 O)} n ( 1 ) has been hydrothermally synthesized from the self-assembly of CuSO 4 , H 2 MoO 4 and 4,4´-H 2 bpz [4,4´-bpz = 3,3´,5,5´-tetramethyl-substituted 4,4´-bipyrazole] and H 2 O. Its structure is composed of rare (CuL) ∞ castellated chains that are linked by two kinds of molybdenum-oxide clusters to form an unusual two dimensional 3-fold interpenetrated structure. Photoluminescent investigation reveals that the title complex displays a strong blue-light emission. A novel polyoxometalate-containing metal–organic hybrid compound with unusual 3-fold interpenetration (6.3) topology was synthesized, which is the first example included two kinds of molybdenum oxide anion clusters [Mo 8 O 26 ] 4 − and [Mo 8 O 26 (OH) 2 ] 6 − . ► A novel polyoxometalate-containing metal – organic hybrid compound with unusual 3-fold interpenetration 2-D (6.3) topology was synthesized. ► It is the first example which included two kinds of molybdenum anion clusters [Mo 8 O 26 ] 4 − and [Mo 8 O 26 (OH) 2 ] 6 − ► It exhibits two kinds of photoluminescent emission.

A new IR non-linear optical material with 2D 3-fold interpenetrated topology

A new IR non-linear optical compound [(Ag4L4)(SiW12O40)] has been hydrothermally synthesized from the self-assembly of silicotungstic acid, 4,4′-H2bpz (L = 4,4′-H2bpz = 3,3′,5,5′-tetramethyl-substituted 4,4′-bipyrazole) and AgF. Its structure is composed of rare (AgL)∞ castellated chains that are linked by polyoxometalate clusters to form an interesting two dimensional 3-fold interpenetrated structure. The title compound is the first example of a polyoxometalate-containing metal–organic hybrid compound that has been shown to have strong SHG effect in IR region and is thermally stable up to ca. 400 °C.

Uniaxial pressure effect on the magnetic properties of the metal-organic hybrid compound CoII(H2O)6pyromellitate

A uniaxial pressure technique is developed to study the dependence of the magnetization up to 12 kbar using a SQUID magnetometer. The technique has been tested for the magnetic properties of a Metal-Organic Framework, Co(H2O)6(C10H4O8), where C10H4O8 is benzene-1,2,4,5-tetracarboxylate, along three orthogonal axes of single crystals. It displays anisotropic paramagnetic properties between 2 and 300 K without any phase transition. The isothermal magnetizations at 5 K show decrease with pressure when the field is applied along the b-axis but an increase along the a-and c*-axes. The results are interpreted as a change in the g-value tensor as a function of pressure due to compression along the Jahn-Teller distorted axis.

A 3D interpenetrating supramolecular compound based on Cu ··· N weak coordination: synthesis, crystal structure and DFT investigation

A metal-organic hybrid compound, Cu[(pyc)2(4,4′-bipy)] · H2O (pyc = pyridine-2-carboxylate, 4,4′-bipy = 4,4′-bipyridine), has been hydrothermally synthesized and characterized by X-ray determination, IR and elemental analysis. The compound crystallizes in tetragonal, space group I41/acd with a = 24.797(2) Å, b = 24.797(2) Å, c = 14.811(2) Å, β = 90°, V = 9106.7(18) Å3, C22 H18N4O5Cu, Mr = 481.94, Dc = 1.406 g cm−3, μ(Mo-Kα) = 0.999 mm−3, F(000) = 3952, Z = 16, the final R = 0.0712 and wR = 0.1886 for 21727 observed reflections (I > 2σ). Compound 1 exhibits a three-dimensional interpenetrating network induced by weak Cu ··· N noncovalent interaction, C–H ··· π and π–π interactions. Based on crystal data, quantum chemistry calculation at the DFT/B3LPY level was used to reveal the electronic structure of 1.

Synthesis and Characterization of Four Metal−Organophosphonates with One-, Two-, and Three-Dimensional Structures

A series of metal-organic hybrid compounds were synthesized using two new phosphonic acids, pyridyl-4-phosphonic acid and p-xylylenediphosphonic acid (H(2)O(3)PCH(2)C(6)H(4)CH(2)PO(3)H(2)). The phosphonic acid ligands have been synthesized from their corresponding bromides following two different types of reactions. The reaction of pyridyl-4-phosphonic acid with three different divalent metal salts results in the formation of molecular structures of different dimensionality. The reaction of Cu(II) with the phosphonic acid under hydrothermal conditions yields a three-dimensional (3D) open framework structure having the molecular formula [Cu(4)(NC(5)H(4)-PO(3))(4)(H(2)O)(10)] (1). The reactions with Mn(II) and Zn(II) salts with the same phosphonic acid resulted in a two-dimensional layered and a dinuclear compound with molecular formulas [Mn(3)(NC(5)H(4)-PO(3))(4)(H(2)O)(6)(ClO(4))(2)] (2) and [Zn(2)(NHC(5)H(4)-PO(3)H)(2)Cl(4)] (3), respectively. Compound 1 crystallizes in the triclinic crystal system having space group P with structural parameters a = 7.4564(15) Angstrom, b = 9.1845(19) Angstrom, c = 11.582(2) Angstrom, alpha = 100.842(3) degrees, beta = 104.303(3) degrees, gamma = 94.774(3) degrees, and Z = 1. Compound 2 crystallizes in the triclinic crystal system, space group P, with structural parameters a = 7.6871(14) Angstrom, b = 10.576(2) Angstrom, c = 14.470(3)Angstrom, alpha = 81.340(3) degrees, beta = 81.561(3) degrees, gamma = 68.757(3) degrees, and Z = 2, whereas compound 3 crystallizes in a monoclinic crystal system with space group P2(1)/n. The structural parameters are as follows: a = 8.4969 (5) Angstrom, b = 9.3911 (5) Angstrom, c = 12.3779 (6) Angstrom, beta = 90.860(17) degrees, and Z = 4. The pyridylphosphonate ligand shows different ligation behavior toward the three divalent metal ions. On the other hand, p-xylylenediphosphonic acid on reaction with Co(II) formed a 3D compound [Co(2)(O(3)PCH(2)C(6)H(4)CH(2)PO(3))(2)(H(2)O)(2)] (4) with a layered and pillared structure. Compound 4 crystallizes in an orthorhombic crystal system with space group Pnma. The structural parameters are a = 21.744(4) Angstrom, b = 5.6744(10) Angstrom, c = 4.7927(9) Angstrom, and Z = 4.

Hybrid inorganic–organic frameworks containing magnesium: Synthesis and structures of magnesium squarate, diglycolate, and glutarate, and potassium magnesium cyclobutanetetracarboxylate

Four new magnesium containing metal–organic hybrid compounds have been synthesized in an effort to prepare low-density materials for hydrogen storage. The compounds were prepared hydrothermally and characterized using single crystal X-ray diffraction. Three of these compounds are analogs of known transition metal structures with squarate ( I, Pn-3 n, a = 16.276(5) Å), diglycolate ( II, P2 12 12 1, a = 6.860(1) Å, b = 9.993(1) Å, c = 10.884(1) Å, R 1 = 0.0341), and glutarate ( III, R-3, a = 10.744(2) Å, c = 28.677(5) Å, R 1 = 0.0554) ligands; the fourth is a novel structure using cyclobutanetetracarboxylate ( IV, Pccn, a = 9.382(1) Å, b = 14.410(2) Å, c = 8.725(1) Å, R 1 = 0.0465) which contains potassium as well as magnesium cations.

Hydrothermal synthesis and crystal structure of an infinite 1D ladderlike metal-organic compound: [Cu 2(btec)(2,2′-bipy) 2] ∞ (btec=1,2,4,5-benzenetetracarboxylate)

A new metal-organic hybrid compound [Cu 2(btec)(2,2′-bipy) 2] ∞ (btec=1,2,4,5-benzenetetracarboxylate) has been hydrothermally synthesized and characterized by elemental analyses, IR spectrum, TG analysis and single-crystal X-ray diffraction. Dark-blue crystals crystallizes in the monoclinic system, space group P2(1)/ n, a=7.2587(15) Å, b=12.396(3) Å, c=14.428(3) Å, β=103.87(3)°, V=1260.4(4) A ̊ 3, Z=2, R1=0.0553, wR2=0.1746. The title compound exhibits a new infinite 1D ladderlike chain architecture constructed from the {Cu(2,2′-bipy)} 2+ moieties and btec ligands. Furthermore, the adjacent chains are stacked into a 3D supramolecular framework via π–π stacking interactions of bipy groups and intermolecular hydrogen bonding interactions.

A novel three-dimensional metal-organic interpenetrating framework constructed from mixed adipate and 4,4′-bipy ligands: [Co(OOC(CH2)4COO)(4,4′-bipy)] (adipate=HOOC(CH2)4COOH, 4,4′-bipy=4,4′-bipyridine)

A novel metal-organic hybrid compound [Co(OOC(CH2)4COO)(4,4′-bipy)] 1, has been hydrothermally synthesized and structurally characterized. Compound 1 exhibits a novel three-dimensional interpenetrating network with mixed adipate and 4,4′-bipy ligands constructed by covalent bonds.