Three-dimensional Coordination Polymer Research Articles

Tailor-made copper(ii) coordination polymers based on the C3symmetric methanetriacetate as a ligand

The construction of coordination polymers based on flexible ligands in a pre-designed manner is a difficult task which needs deep knowledge of the ligands involved. With this objective in mind, we have investigated the complex formation between methanetriacetic acid (H3mta) and copper(II) in the presence of 2,2′-bipyridine (bpy) as a blocking coligand to limit the number of coordination sites available at the metal ion. In this primary target, five complexes of formulae [Cu3(bpy)6(mta)](ClO4)3·2H2O (1), [Cu4(bpy)6(mta)2(H2O)2](ClO4)2·20H2O (2), [Cu(bpy)(Hmta)]n (3), {[Cu4(bpy)4(mta)2](ClO4)2·3H2O}n (4) and {[Cu3(mta)2(bpy)3(H2O)]3·3dmf·13H2O}n (5) were synthesized and their crystal structures were solved by single crystal X-ray diffraction. Compounds 1 and 2 are tri- and tetranuclear species, respectively, whereas 3 and 4 are one-dimensional compounds and 5 is a three-dimensional coordination polymer. This series of complexes reveals that methanetriacetate behaves as a tritopic ligand which keeps its C3 symmetry despite its flexibility. On the basis of the structural knowledge of 1–5, a (6,3)-honeycomb network of formula {[Cu12(tppz)6(mta)4(H2O)24](NO3)12·66H2O}n (6) [tppz = tetrakis(2-pyridyl)pyrazine] was prepared by design where each methanetriacetate ligand acts as a three-connected node. Magnetic susceptibility measurements in the temperature range 2.0–300 K for 1–6 show the occurrence of very weak antiferro- (1 and 2) and ferromagnetic (3–5) interactions, whereas an intermediate antiferromagnetic coupling (J = −43 cm−1, the spin Hamiltonian being defined as H = −JS1·S2) is observed for 6. The different size and nature of the magnetic interactions in 1–6 are analyzed and discussed in the light of the respective exchange pathways involved.

Crystal structure analysis of supramolecular arrangements in bis(1-isoquinolinecarboxamide)alkanes and their Ag(i) complexes

A homologous series of bis(1-isoquinolinecarboxamide)alkane derivatives (3a–f) with two to seven carbon atoms in the alkyl bridge and their Ag(I) complexes (4a–f) have been synthesized. Four ligand and five Ag(I) complex crystal structures were obtained by single crystal X-ray diffraction and analyzed in terms of: a) their structural patterns based on intra- and intermolecular hydrogen bonds which were compared to those of bis(2-quinolinecarboxamide)alkanes (1n) and bis(6-quinolinecarboxamide)alkanes (2n) attending to specific geometrical parameters and b) the Ag(I) coordinate bond effect on these patterns and the amide-to-amide hydrogen bonds. The crystal structures of the ligands 3a, 3c, 3d and 3e synthesized here show amide-to-amide interactions, the same as those occurring in the 2n derivatives, forming one or two-dimensional structures (β-sheets or 4,4-networks) via N–H⋯O(amide) hydrogen bonds. The coordinate bond in the 4n complexes predominates over the amide-to-amide hydrogen bond giving rise to structures ranging from discrete complexes to three-dimensional coordination polymers. Only the 4c complex merges supramolecular β-sheets connected by the silver coordination bonds.

Syntheses, Structures, Luminescence, and Magnetic Properties of a Series of Novel Coordination Polymers Constructed by Nanosized [Ln8Fe4] Rings

A total of five three-dimensional Ln-Fe coordination polymers (CPs) [(CH3)2NH][(CH3)2NH2][Ln2Fe(SO4)4(L)]·3H2O (Ln = Eu, 1; Dy, 2; Gd, 3; Sm, 4; Er, 5; H2L = tartaric acid) have been successfully synthesized under solvothermal conditions and characterized by infrared spectroscopy, thermogravimetric analysis, elemental analyses, luminescence, and magnetic properties. Structural analysis indicates that the frameworks of 1–5 are constructed from novel [Ln8Fe4] rings. In the strcutures of 1–5, LnIII and FeIII ions interconnect through O donors of sulfate anions to generate a one-dimensional chain, and the adjacent chains are joined together by ligand [L]2– to form a two-dimensional zonary plane, which is further bridged by ligand [L]2– to give a new topology and named as “Xhd1”. Magnetic properties of 2 and 3 were investigated using variable temperature magnetic susceptibility, and weak ferromagnetic exchange between the FeIII and LnIII ions has been established for the Gd derivative. Meanwhile, we also studi...

Dynamic Uptake and Release of Water in the Mixed-Metal EDTA Complex M3[Yb(EDTA)(CO3)] (M = K, Rb, Cs)

Ethylenediaminetetraacetic acid (H4EDTA) acts as a multidentate ligand toward ytterbium nitrate in the presence of M2CO3 (M = K, Rb, Cs). All structurally characterized compounds are three-dimensional coordination polymers with eight-coordinated ytterbium and three alkali metal cations in the asymmetric unit. In the presence of potassium cations, two different phase pure reaction products can be obtained. From a water-containing solution, first a water-deficient compound with composition K3[Yb(EDTA) (CO3)](H2O)·H2O precipitates. When kept in the reaction mixture, this kinetic product transforms into the more water-rich mixed-metal coordination network K3[Yb(EDTA)(CO3)](H2O)4·2H2O; alternatively, the conversion can be achieved by isolating the water-deficient product and immersing it into a water-containing solvent. The reverse reaction, partial dehydration, may be induced by prolonged drying in a desiccator, vacuum treatment, or heating. For the heavier alkali cations Rb+ and Cs+, only one crystalline str...

Self-assembly of one-dimensional nitrogen-doped hollow carbon nanoparticle chains derived from zinc hexacyanoferrate coordination polymer for lithium-ion capacitors

One-dimensional nitrogen-doped hollow carbon nanoparticle chains (CNCs) featuring bimodal pore size distribution were obtained by direct thermal pyrolysis of a three-dimensional cyanide-bridged coordination polymer precursor (zinc hexacyanoferrate) without the need for additional carbon, nitrogen, and catalyst sources. Nitrogen doping turned out to play the key role in the formation of mesoporous compartment layers and structural defects in the CNCs. Small mesopores in the walls provided high surface area for charge storage and allowed the migration of electrolyte into the compartments. Large mesopores in the hollow compartments accommodated electrolyte for easy transport of lithium ions. The commercial multiwalled carbon nanotube (CNT) electrode stored lithium ions primarily through the intercalation process, while the CNC electrode stored lithium ions through both the intercalation and adsorption processes. Thus, the CNC electrode exhibited superior supercapacitive performance than the CNT electrode. The CNC electrode with low internal resistance could deliver a high capacitance of 680Fg−1 at 1Ag−1 in the working potential range of 0.01-3.50V vs. Li/Li+, which was much better than the commercial CNT electrode (252Fg−1).

Sonochemical Synthesis of a Nanosized Coordination Polymer with Catalytic Activity for Selective Epoxidation of Olefins

A three-dimensional coordination polymer, {(Mo2O6)(4,4′-bpy)}n (1) (4,4′-bpy=4,4′-bipyridine), was synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction analysis, powder X-ray diffraction (XRD), Fourier transformation infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The coordination polymer was also prepared in nanoscale via an ultrasound-assisted top-down process. The nanosized coordination polymer was characterized by means of scanning electron microscopy (SEM), XRD and FT-IR spectroscopy. The prepared oxomolybdate-based coordination polymer, in bulk and nanoscale, was applied as heterogeneous catalyst for the epoxidation of some olefins using tert-butyl hydroperoxide (TBHP) as oxidant. The 3-D coordination polymer, particularly in nanoscale, demonstrated good activity and stability in the epoxidation reaction and could be easily recovered and reused in the reaction.

A three-dimensional coordination polymer of cobalt(II) dicyanamide containing an in situ generated didentate Schiff base : Synthesis, structure and magnetic property

A three-dimensional coordination polymer of cobalt(II) dicyanamide containing an in situ generated didentate Schiff base : Synthesis, structure and magnetic property

Two novel CPs with double helical chains based rigid tripodal ligands: Syntheses, crystal structures, magnetic susceptibility and fluorescence properties

Two three-dimensional coordination polymers (CPs), namely [Cd(bpydb)- (H2bpydb)]n·0.5nH2O (1), and [Cu2(bpydb)2]n (2) (2,6-di-p-carboxyphenyl-4,4’- bipyridine1 = H2bpydb), containing a novel double-helical chains, which have been solvothermal synthesized, characterized, and structure determination. CPs 1-2 reveal the new (3,5)-net and (3,6)-net alb topology, respectively. The fluorescence properties of CPs 1-2 were investigated, and magnetic susceptibility measurements indicate that compound 1 has dominating antiferromagnetic couplings between metal ions.

Nitrilotris(methylenephosphonato)potassium K[μ6-NH(CH2PO3)3H4]: Synthesis, structure, and the nature of the K–O chemical bond

The crystal structure of nitrilotris(methylenephosphonato)potassium K[μ6-NH(CH2PO3)3H4]—a three-dimensional coordination polymer—was determined. The potassium atom is coordinated by seven oxygen atoms belonging to the six nearest ligand molecules, resulting in distorted monocapped octahedral coordination geometry. The complex contains the four-membered chelate ring K–O–P–O. The K–O chemical bond is predominantly ionic. Meanwhile, the bonds of the potassium atom with some oxygen atoms have a noticeable covalent component. In addition to coordination bonds, the molecules in the crystal packing are linked by hydrogen bonds.

Synthesis, crystal structure, and magnetic properties of a two-fold interpenetrated diamondoid open framework

Self-assembly of an enlarged angular pyridinecarboxylate ligand and cobalt(II) acetate under mild conditions afforded a three-dimensional open-framework coordination polymer, [Co2(μ-H2O)(pyca-43)4]n (1, Hpyca-43=(E)−3-((pyridin-4-yl)methyleneamino)benzoic acid). The molecular structure of 1 has rationalized to be a porous two-fold interpenetrated diamondoid-like network, with dinuclear Co2(μ-H2O)(O2C)4N4 clusters as tetrahedral secondary building units (SBUs), possessing highly solvent accessible volume of approximately 53.0%. Least-squares fit of the magnetic susceptibility data (20–300K) of 1 yields Curie constant C=6.15cm3mol–1 K and Weiss constant θ=–11.6K. Every Co2 subunit within the network is magnetically insulated to other dimers. The magnetic exchange parameter between Co(II) centers is estimated to −0.72cm–1, suggesting a weak antiferromagnetic interaction. The gav value of 4.65 from fitting to the Lines model indicates that the decrease of the χMT value upon cooling is dominated by depopulation of the excited Kramer's states to the effective ground singlet. In addition, the thermal stability and adsorption properties of 1 are also reported.

A Luminescent Three-Dimensional Coordination Polymer Based on Cu(I) Halide Clusters Showing Dia Topology with 8-Fold Interpenetration

One interesting copper(I) halide-based coordination polymer with a formula of [Cu4(Br)4(bib)2]n (1) (bib = 1,4-bis(imidazol-2-methyl)butane) has been prepared by solvothermal method, and characterized by X-ray single crystal diffraction, elemental analyses, IR and TGA. Structure analyses reveal that the compound is constructed of copper(I) halide clusters and flexible bib ligands, which features a 8-fold interpenetrated 3D framework with 4-connected extended dia topology. Furthermore, the compound exhibits high thermal stability and intense fluorescent emission, and can be explored for potential red luminescent materials.

A new three-dimensional zinc(II) coordination polymer involving 2-[(1H-1,2,4-triazol-1-yl)methyl]-1H-benzimidazole and benzene-1,4-dicarboxylate ligands.

Metal-organic frameworks (MOFs) based on multidentate N-heterocyclic ligands involving imidazole, triazole, tetrazole, benzimidazole, benzotriazole or pyridine present intriguing molecular topologies and have potential applications in ion exchange, magnetism, gas sorption and storage, catalysis, optics and biomedicine. The 2-[(1H-1,2,4-triazol-1-yl)methyl]-1H-benzimidazole (tmb) ligand has four potential N-atom donors and can act in monodentate, chelating, bridging and tridentate coordination modes in the construction of complexes, and can also act as both a hydrogen-bond donor and acceptor. In addition, the tmb ligand can adopt different coordination conformations, resulting in complexes with helical structures due to the presence of the flexible methylene spacer. A new three-dimensional coordination polymer, poly[[bis(μ2-benzene-1,4-dicarboxylato)-κ(4)O(1),O(1'):O(4),O(4');κ(2)O(1):O(4)-bis{μ2-2-[(1H-1,2,4-triazol-1-yl)methyl-κN(4)]-1H-benzimidazole-κN(3)}dizinc(II)] trihydrate], {[Zn(C8H4O4)(C10H9N5)]·1.5H2O}n, has been synthesized by the reaction of ZnCl2 with tmb and benzene-1,4-dicarboxylic acid (H2bdic) under solvothermal conditions. There are two crystallographically distinct bdic(2-) ligands [bdic(2-)(A) and bdic(2-)(B)] in the structure which adopt different coordination modes. The Zn(II) ions are bridged by tmb ligands, leading to one-dimensional helical chains with different handedness, and adjacent helices are linked by bdic(2-)(A) ligands, forming a two-dimensional network structure. The two-dimensional layers are further connected by bdic(2-)(B) ligands, resulting in a three-dimensional framework with the topological notation 6(6). The IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis and the title polymer exhibits good fluorescence in the solid state at room temperature.

A Novel Mn(II) Coordination Polymer Based on Carboxylate and Tris[4-(1Himidazol-1-yl)-phenyl]amine Coligands With a Rare hms Topology: Solvothermal Synthesis, Crystal Structure, and Luminescent Property

A new three-dimensional coordination polymer [Mn(BPDC) (TIPA)]·DMF·H2O (1) (H2BPDC = biphenyl- 3,4′-dicarboxylate, TIPA = tris[4-(1H-imidazol-1-yl)-phenyl]amine and DMF = N,N-dimethylformamide) was solvothermal synthesized by the assembly of Mn2+ ion, H2BPDC and TIPA, respectively. The title complex [Mn(BPDC) (TIPA)]· DMF·H2O (1) was characterized by IR, elemental analysis, X-ray powder diffraction, and single-crystal X-ray diffraction. Structure analysis reveals that complex 1 display a 3,5-connected twofold interpenetrated hms topology. Moreover, the luminescent property for complex 1 is investigated at room temperature.

Hydrothermal Synthesis, Crystal Structure, and Luminescent Property of a New Cd(II) Coordination Polymer With Three-Fold Interpenetrated pcu Topology

A new three-dimensional (3D) coordination polymer, [Cd(pda)(bib)0.5] n(1), [H2pda=1,4-phenylenediacetic acid and bib=1,4-bis(2-methyl-imidazol-1-yl) butane] was prepared by hydrothermal syntheses and characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, and elemental analysis. Crystal structure determination revealed that complex 1 features a threefold interpenetrated pcu framework. Furthermore, the luminescent property for complex 1 is also investigated in solid state at room temperature.

(113)Cd Nuclear Magnetic Resonance as a Probe of Structural Dynamics in a Flexible Porous Framework Showing Selective O2/N2 and CO2/N2 Adsorption.

Two new isomorphous three-dimensional porous coordination polymers, {[Cd(bpe)0.5(bdc)(H2O)]·EtOH}n (1) and {[Cd(bpe)0.5(bdc)(H2O)]·2H2O}n (2) [bpe = 1,2-bis(4-pyridyl)ethane, and H2bdc = 1,4-benzenedicarboxylic acid], have been synthesized by altering the solvent media. Both structures contain one-dimensional channels filled with metal-bound water and guest solvent molecules, and desolvated frameworks show significant changes in structure. However, exposure to the solvent vapors (water and methanol) reverts the structure back to the as-synthesized structure, and thus, the reversible flexible nature of the structure was elucidated. The flexibility and permanent porosity were further reinforced from the CO2 adsorption profiles (195 and 273 K) that show stepwise uptake. Moreover, a high selectivity for O2 over N2 at 77 K was realized. The framework exhibits interesting solvent vapor adsorption behavior with dynamic structural transformation depending upon the size, polarity, and coordination ability of the solvent molecules. Further investigation was conducted by solid state (113)Cd nuclear magnetic resonance (NMR) spectroscopy that unambiguously advocates the reversible transformation "pentagonal-bipyramidal CdO6N → octahedral CdO5N" geometry in the desolvated state. For the first time, (113)Cd NMR has been used as a probe of structural flexibility in a porous coordination polymer system.

The crystal structure and photocatalytic properties of a three-dimensional cadmium(II) metal-organic framework: poly[bis(μ3-benzene-1,2-dicarboxylato)[μ2-1,4-bis(pyridin-3-ylmethoxy)benzene]dicadmium(II)

Photocatalysis is a green technology for the treatment of all kinds of contaminants and has advantages over other treatment methods. Recently, much effort has been devoted to developing new photocatalytic materials based on metal-organic frameworks for use in the degradation of many kinds of organic contaminants. With the aim of searching for more effective photocatalysts, the title three-dimensional coordination polymer, [Cd2(C8H4O4)2(C18H16N2O2)]n, was prepared. The asymmetric unit contains one Cd(II) cation, one benzene-1,2-dicarboxylate anion (denoted L(2-)) and half of a centrosymmetric 1,4-bis(pyridin-3-ylmethoxy)benzene ligand (denoted bpmb). Each Cd(II) centre is five-coordinated by four carboxylate O atoms from two L(2-) ligands and by one N atom from a bpmb ligand, forming a disordered pentagonal pyramidal coordination geometry. The Cd(II) centres are interlinked by L(2-) ligands to form a one-dimensional [Cd2L2]n chain. Adjacent chains are further connected by bpmb linkers, giving rise to a two-dimensional network, and these networks are pillared by bpmb to afford a three-dimensional framework with a 3(3).4(2).6(3).7(1).8(1) topology. Each grid in the framework has large channels which are filled mainly by the two other equivalent frameworks to form a threefold interpenetrating net. The compound exhibits relatively good photocatalytic activity towards the degradation of methylene blue in aqueous solution under UV irradiation.

Crystal structure of a mixed-ligand terbium(III) coordination polymer containing oxalate and formate ligands, having a three-dimensional fcu topology.

The title compound, poly[(μ 3-formato)(μ 4-oxalato)terbium(III)], [Tb(CHO2)(C2O4)] n , is a three-dimensional coordination polymer, and is isotypic with the La(III), Ce(III) and Sm(III) analogues. The asymmetric unit contains one Tb(III) ion, one formate anion (CHO2 (-)) and half of an oxalate anion (C2O4 (2-)), the latter being completed by application of inversion symmetry. The Tb(III) ion is nine-coordinated in a distorted tricapped trigonal-prismatic manner by two chelating carboxyl-ate groups from two C2O4 (2-) ligands, two carboxyl-ate oxygen atoms from another two C2O4 (2-) ligands and three oxygen atoms from three CHO2 (-) ligands, with the Tb-O bond lengths and the O-Tb-O bond angles ranging from 2.4165 (19) to 2.478 (3) Å and 64.53 (6) to 144.49 (4)°, respectively. The CHO2 (-) and C2O4 (2-) anions adopt μ 3-bridging and μ 4-chelating-bridging coordination modes, respectively, linking adjacent Tb(III) ions into a three-dimensional 12-connected fcu topology with point symbol (3(24).4(36).5(6)). The title compound exhibits thermal stability up to 623 K, and also displays strong green photoluminescence in the solid state at room temperature.

MOF-71 as a degradation product in single crystal to single crystal transformation of new three-dimensional Co(ii) 1,4-benzenedicarboxylate

A new three-dimensional coordination polymer, {[Co(μ2-H2O)(bdc)(H2O)(dmf)]·0.5H2O}n (1), was obtained as a by-product in the synthesis of the laminar solid {[Co2(μ2-H2O)(bdc)2(S-nia)2(H2O)(dmf)]·(dmf)2·H2O}n (2) (where H2bdc = 1,4-benzenedicarboxylic acid, S-nia = thionicotinamide, dmf = N,N′-dimethylformamide). The three-dimensional network in 1 is organized of Co(II) atoms in O6 octahedral coordination environments separated by μ2-water molecules in coordination chains. The bdc2− anions coordinate in monodentate mode and also act as bridging ligands that extend the structure in two other directions. The coordination cores of two crystallographically different Co(II) atoms are completed by either two dmf or two water molecules. The rhombohedral open channels contain water molecules. The evacuation of solvents from 1 occurs as a single crystal to single crystal transformation and results in MOF-71, [Co(bdc)(dmf)]n, whose structure was confirmed by single crystal X-ray diffraction.

Dinitrogen-supported coordination polymers

Two novel three-dimensional dinitrogen-supported coordination polymers adopting the (53·73)2(54·82) and (53)4(58·64·78·84·94)2-3,8T16 topologies are reported.

Synthesis, Characterization and X-Ray Structure of a Ba(II)/Ag(I)/Cr(III)-Oxalate Salt with Water-Filled Nanochannels

A novel mixed barium(II)/silver(I)/chromium(III) oxalate salt, Ba0.5Ag2[Cr(C2O4)3]·5H2O (1), with open architecture has been synthesized in water and characterized by elemental analysis, vibrational and electronic spectra, and single crystal X-ray structure determination. Compound 1 crystallizes in a monoclinic space group C2/c, with unit cell parameters a = 18.179(3), b = 14.743(2), c = 12.278(2)A, β = 113.821(3), V = 3010.34(90) A3, Z = 8. The structure is characterized by a network of anionic [Cr(C2O4)3]3- units connected through the O atoms of the oxalates to Ba2+ and Ag+ sites, forming a three-dimensional coordination polymer with one-dimensional isolated nanochannels parallel to the c axis, and encapsulating hydrogen-bonded guest water molecules. The bulk structure is consolidated by O–H···O bridgings within the nanochannels and by coulombic interactions.