Synthesis and Structures of Two Ba(II) Metal–Organic Frameworks Based on Pyridine-2,6-Dicarboxylic Acid N-Oxide

Hydrothermal and solution reactions of pyridine-2,6-dicarboxylic acid N-oxide (2,6-PDCO) and BaCl₂·2H₂O yield two metal–organic frameworks; namely [Ba(2,6-PDCO)] _n (1) and [Ba(2,6-PDCO)·H₂O] _n (2), respectively. Single-crystal X-ray analyses reveal that compound 1 is a dense framework whereas compound 2 is a porous one, though both compounds have an infinite two-dimensional (2D) layer structure. Compounds 1 and 2 are the first examples of pyridine dicarboxylic acid N-oxide introduced into the alkaline earth metal–organic framework.     

Hydrothermal Synthesis of Cd(II), Mn(II) and Ni(II) Coordination Polymers Derived from Benzopenone-2,4′-carboxylate and N-door Ligands

Three new coordination polymers [Cd(L)(4,4′-bipy)_0.5]_n (1), {[Mn(L)(bpp)]·H₂O}_n (2) and [Ni(L)(2,2′-bipy)(H₂O)₂]_n(3) [H₂L = Benzopenone-2,4′-dicarboxylic acid, 4,4′-bipy = 4,4′-bipy ridine, bpp = 1,3-di(4-pyridyl) propane and 2,2′-bipy = 2,2′-bipyridine] have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses revealed that the H₂L ligand acts as a bridge, exhibiting three coordination modes to link metal ion: bidentate chelating, bis-monodentate, monodentate. Compound 1 has 3-connected metal–organic framework with the (6³) topology notation; Compounds 2 and 3 are one-dimensional chain structures. The luminescent properties for compound 1 was investigated.     

Hydrothermal Crystal Growth,Structures and Thermal Properties of Co(II)-4,4′-bipyridine-Based Coordination Polymeric Materials

Hydrothermal synthetic parameters were studied and optimized for the preparation of new coordination polymeric materials based on Co(II) and 4,4′-bipy. A new polymeric compound, [Co₂(H₂O)₂(OH)₂(4,4′-bipy)₈](NO₃)₂·2(4,4′-bipy) 10(H₂O) (1), was prepared and structurally characterized by single crystal experiment. The framework of (1) is made up of two different one-dimensional substructures, i.e., the neutral chain A and positively charged chain B, both of which share the same nodes and node linkers. This is rarely found, especially from a one-pot crystal growth technique. Two other crystals were also identified, i.e., [Co(SO₄)(H₂O)₃(4,4′-bipy)]·2(H₂O), and K₂Co(H₂O)₆(SO₄)₂. The optimization of synthetic parameters apparently favors the formation of different polymeric structures, and this can be experimentally fine tuned. The influences of these parameters on phase formation, purity and crystal growth are discussed. The complicated thermogravimetric property of the new compound is also reported.     

Double-layer structure,sorption and magnetism properties of metal–organic frameworks with trigonal planar ligand

A new double-layer metal–organic framework [Co₃(tcpt)₂(H₂O)₂] (1) has been synthesized using trigonal planar ligand 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine (H₃tcpt) as a bridging ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR, PXRD and TGA. Structure analysis reveals that compound 1 has a double-layer structure. Gas sorption measurements indicate that compound 1 exhibits selective adsorption capabilities for CO₂ over CH₄ and N₂. Furthermore, the magnetic studies of compound 1 show antiferromagnetic interactions between Co(II) ions.     

An effective approach for constructing acentric heterometallic-organic framework with catalytic activity

A new acentric heterometallic–organic framework, [CdMg (btec)(DMF)(H₂O)₃] (1) (H₄btec = 1,2,4,5-benzene tetracarboxylic acid), has been solvothermally synthesized. It features a 4-connected net with typical pts topology. To the best of our knowledge, compound 1 is the first example of Cd–Mg heterometallic organic framework based on the H₄btec ligand. Compound 1 has potential unsaturated metal sites after the removal of coordination water molecules, so it shows good catalytic activity on the diethylzinc addition to benzaldehyde. The photoluminescent property of 1 is also investigated.     

An inorganic–organic hybrid compound built from polyoxovanadate cluster and Mn (II) complexes

A novel inorganic–organic hybrid compound [Mn(teta)][Mn(teta)(H₂O)₂]₂{V₁₈O₄₂(Cl)}·8H₂O (1) (teta: triethylenetetramine) has been hydrothermally synthesized and characterized by TGA, IR and XPS analysis. Its structure is determined by single-crystal X-ray diffraction analysis. Compound 1 exhibits a rare 2-D planar square lattice (sql net), which was constructed by the well known {V₁₈O₄₂} cluster as node and two distinct Mn (II) complexes, [Mn(teta)] and [Mn(teta)(H₂O)₂], as single/double μ₂-bridging linkers. This type sql net with two distinct Mn (II) complexes is the first example found in polyoxovanadates. The magnetic study shows that there exists antiferromagnetic interaction within 1.     

Synthesis,structure of a coordination polymer: {Na2[Zn(C2O4)1.5H2PO4] · 2H2O}n

A phosphatooxalate compound {Na₂[Zn(C₂O₄)_1.5H₂PO₄] · 2H₂O}_n 1 was synthesized under hydrothermal condition and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetric analysis (TGA) and fluorescent spectroscopy. X-ray single-crystal analysis revealed that its structure was a new mixed inorganic–organic ligand supramolecular framework building up through multilayer assembly.     

Zinc(II) Metal–Organic Framework with Nano-Sized Channels Based on Paddle-Wheel Units

A Zn(II) metal–organic framework with nano-sized channels from 4,4′-bipyridine (4,4′-bipy) and 4′-sulfo-biphenyl-4-carboxylate (sbpc²⁻) ligands, {[Zn(μ-4,4′-bipy)_1.5(μ-sbpc)]·5H₂O} _n (1), has been synthesized by the hydrothermal method. Compound 1 was characterized by X-ray powder diffraction, IR spectroscopy, elemental analysis and single-crystal X-ray crystallography. The structural studies show the Zn atoms have a six-coordinate geometry with a distorted octahedral environment constructed of paddle-wheel [Zn₂(OOC)₄] building units with 4,4′-bipy and sbpc²⁻ linkers stacked over each other to generate three-dimensional nano-sized channels occupied by guest H₂O molecules.     

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.     

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.     

A robust microporous ytterbium metal-organic framework with open metal sites for highly selective adsorption of CO2 over CH4

A rare three-dimensional (3D) microporous lanthanide metal–organic framework, {[Yb(BTB)(H₂O)](MeOH)₂(H₂O)}_n (1), with 1D nano-sized channels has been constructed by bridging helical chain secondary building units with 1,3,5-Benzenetrisbenzoic acid (H₃BTB) ligand. The highly rigid and stable framework contains a 1D triangular channel-type structure with highly polar pore surfaces decorated with abundant open metal sites. The desolvated framework {[Yb(BTB)]}_n is found to exhibit permanent porosity with high CO₂ storage capacities and significant selective sorption of CO₂ over CH₄ around room temperature.     

Synthesis and crystal structure of [Cu(4-OOCC6H4CN)2(4-HOOCC6H4CN)(H2O)2]·2(4-HOOCC6H4CN): a hydrogen bonded assembly of the first transition metal complex of 4-cyanobenzoic acid

The first transition metal complex of 4-cyanobenzoic acid, [Cu(4-OOCC₆H₄CN)₂(4-HOOCC₆H₄CN)(H₂O)₂]·2(4-HOOCC₆H₄CN), has been prepared in aqueous medium. X-ray single crystal structure analysis reveals that it is a monometallic complex. Five-coordination Cu(II) ion is approximately in a square based pyramidal environment. Three-dimensional network of this compound is formed through O–H…N, O–H…O, C–H…O and C–H…N hydrogen bonding interactions, yielding a grid framework containing dimers of 4-cyanobenzoic acid with carboxylic dimer synthons locating in the channels.     

Structures and photoluminescence of coordination polymers assembled from bifunctional ligand containing both tetrazole and imidazole groups

Three new coordination polymers, namely, {[Cu₂(IPT)(SO₄)(OH)(H₂O)]·H₂O}_n (HIPT = 5-(4-(1H-imidazol-1-yl)phenyl)- 1H-tetrazolate, 1), {[Cd₂(IPT)(NPA)(OH)]·H₂O}_n (H₂NPA = 5-nitroisophthalic acid, 2), and {[Zn₂(IPT)(IDC)(H₂O)]·3H₂O}_n (H₃IDC = 1H-imidazole-4,5-dicarboxylic acid, 3), were assembled from a bifunctional organic ligand containing both tetrazole and imidazole groups with/without the aid of carboxylate coligands. Compound 1 possesses 2D structure built by 1D [Cu₂(IPT)(SO₄)(OH)]_n secondary building blocks and IPT⁻ linkers. The 2D networks are linked into 3D supramolecular framework via water chains in helical conformation. Compound 2 displays 3D pillar-layer framework with 2D layers based on tetranuclear Cd(II) SBUs and NPA^2 − pillars. Compound 3 exhibits a 3D framework constructed from the interconnection of 1D [Zn-IDC]_n chains and binuclear Zn₂(IPT)₂ rings. The thermal stabilities of porous compound 3 and luminescent properties of compounds 2 and 3 have also been studied in detail. They exhibit intense solid-state fluorescent emissions at room temperature.     

Simple Directed Material Design Through in Situ Substitution of Proton with Cu+ Ions

A new inorganic–organic hybrid material (C₁₀H₈N₂H)₂(Mo₈O₂₆) · 2NH₄ (1) was prepared under solvothermal conditions (H₂O/ethanol), which was then used as a starting material in the synthesis of another material, (C₁₀H₈N₂Cu)₂(Mo₈O₂₆) · 2NH₄ (2). Each compound has been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, thermogravimetric analysis, fluorescence, FT-IR, and bond valence sum calculations. The comparative study focuses on the transformation and structural change between 1 and 2, which arises from the simple substitution of the proton in 1 with the Cu⁺ ions. The other surprising feature is that Cu⁺ ions can not only directly be used to substitute the proton of 1 but also ameliorate its photoluminescence property. It means that 1 appears to have recognizable functional protons in the solid-state structure and, hence, can very well be considered as an ideal precursor agent to design the functional materials with special architectures and photoactive properties.     

An unprecedented ten-connected 3D metal–organic framework based on hexanuclear cobalt(II) cluster building blocks

A 3D metal–organic framework (MOF), [Co₃(μ₃-OH)(μ₂-H₂O)(BPT)(HBPT)(DMF)₂]·(DMF)(H₂O) (1) (DMF = N, N′-dimethylformamide) has been synthesized by self-assembly of cobalt(II) oxide and biphenyl-3, 4′, 5-tricarboxylate (H₃BPT) under solvothermal reaction. Compound 1 displays unique (2,3,10)-connected trinodal connected topology. Besides, 1 represents a rare example of MOF possessing free carboxylic acids. In addition, the magnetic property of the compound is investigated.     

Two 2D inorganic–organic hybrid materials constructed from (V2O6)n2n− chains linked through metal–organic units [Cd(ip)]/[Ni(ip)(H2O)]

Two novel inorganic–organic hybrids [Cd(ip)V₂O₆] (1) and [{Ni(H₂O)(ip)}V₂O₆ ]·H₂O (2) {ip = imidazo[4,5-f ][1,10]-phenanthroline} have been prepared and characterized by single crystal X-ray diffraction, IR and TG. Two-dimensional frameworks of the two title compounds are constructed from arrays of (V₂O₆)_n^2n? oxovanadate chains covalently linked through metal–organic units, {Cd(ip)} and {Ni(ip)(H₂O)}. The {M/V/O/N} layers are composed of corner sharing {VO₄} tetrahedra and {MN₂O₄} octahedra. In compound 1, the cadmium ions are bridged alternately by two μ₃-O and two VO₄ units, generating alternated four-membered Cd₂O₂ and eight-membered Cd₂V₂O₄ rings, while the nickel ions of compound 2 are linked simultaneously by VO₄ and V₃O₁₀ units into twelve-membered Ni₂V₄O₆ ring. The ip groups, bonded to the metal centers in the layers, project outward to occupy regions in between the successive metal oxide layers. Furthermore, the adjacent layers [Cd(ip)V₂O₆]_n in compound 1 are linked with each other by hydrogen bonding to generate an interesting 3D supramolecular framework.     

A 2D pillar-layered coordination framework with meso-helix constructed from imidazole-4,5-dicarboxlylate and terephthalate

A new pillar-layered coordination framework [Er(H₂O)(C₅H₂N₂O₄)(TA)_0.5]_n (1) has been hydrothermally synthesized by employing imidazole-4,5-dicarboxlylate (H₃IDC) and terephthalate (H₂TA) and structurally characterized. Single crystal X-ray diffraction analysis reveals that compound 1 exhibits the 2D pillar-layered coordination framework with meso-helical character constructed from auxiliary ligand TA^2? (that is, pillar) bridging two [Er(HIDC^2?)]_n layers (namely, Δ- and Λ-layers), which is the first example of lanthanide coordination framework including imidazole-4,5-dicarboxlylate and terephthalate. Meanwhile, the thermogravimetric analysis shows compound 1 has high thermal stability.     

Metal-organic fameworks based on multi-carboxylate ligands with threefold symmetries and luminescence properties

Three new metal–organic frameworks, namely, [Cd_1.5(tcpb)(DMF)(H₂O)] (1), [Co_1.5(tcpb)(DMF)₂]·3DMF (2) and [Zn(Htcpb)(4,4′-bpy)_0.5]·1.5H₂O (3) (tcpb = 1.3,5-tris(4-carbonylphenyloxy)benzene) have been synthesized by solvent-thermal method. The single-crystal X-ray diffraction analysis shows that compound 1 is 2D grid layers, with the trinuclear cadmium clusters acting as secondary building units (SBUs), and the tcpb ligand serveing as organic linkers. Compound 1 and Compound 2 are isomorphic structures containning similar connection modes of tcpb ligands with trinuclear metal clusters. Compound 3 is a 3D interpenetrated framework based on dinuclear Zn cluster with dia topology. The fluorescence properties for solid state compound 1 and 3 were examined at room temperature. Compared with free tcpb ligands, both of them display remarkable red-shift.     

Synthesis, Structure and Electrochemical Property of a New Three-Dimensional Inorganic–Organic Vanadate Coordination Polymer [Cu2(bbi)2(V4O12)] · 4H2O (bbi = 1,1-(1,4-butanediyl)bis(imidazole))

A new inorganic–organic vanadate coordination polymer [Cu₂(bbi)₂(V₄O₁₂)] · 4H₂O (bbi = 1,1-(1,4-butanediyl)bis(imidazole)) (1) has been synthesized under hydrothermal condition and characterized by elemental analyses, IR spectra and single crystal X-ray diffraction. Structure analysis revealed that the three-dimensional structure of compound 1 is constructed from two-dimensional [Cu(bbi)₂]²⁺ layers linked through {V₄O₁₂}⁴⁻ building blocks. Compound 1 represents the first example of metal-organic frameworks with non-interpenetrated five-connected topological network (4⁶·6⁴) based on Cu(II) as nodes, bbi and {V₄O₁₂}⁴⁻ as mixed spacers. The electrochemical behavior of 1 modified carbon paste electrode (1-CPE) in 1M H₂SO₄ aqueous solution has been studied. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A new three-dimensional 4,8-connected inorganic open framework based on manganese phosphomolybdate with (41261284) (46)2 topology

A new inorganic open framework based on manganese phosphomolybdate, (C₂N₂H₁₀)₄{Mn₃[P₄Mo₆O₂₆(OH)₅]₂}·6H₂O (1), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy and TG analysis. Single-crystal X-ray diffraction analysis reveals that compound 1 exhibits a 4,8-connected three-dimensional inorganic open framework with (4¹²6¹²8⁴) (4⁶)₂ topology and possesses three-dimensional channels filled by the protonated H₂en ligands and water molecules. Additionally, DC susceptibility measurement shows the antiferromagnetic character of the exchange interactions in compound 1.