A Unique Cobalt(II)-Based Molecular Magnet Constructed of Hydroxyl/Carboxylate Bridges with a 3D Pillared-Layer Motif

Structures and magnetic properties of two heterometallic Cu(ii)–Cd(ii) polymers exhibiting antiferromagnetic ordering

Two heterometallic Cu(ii)–Cd(ii) polymers (1 and 2) with a 2D layer or 1D chain structure were obtained and their magneto-structural correlations were discussed, and 1 displayed antiferromagnetic ordering at lower temperature.

Three novel topologically different metal–organic frameworks built from 3-nitro-4-(pyridin-4-yl)benzoic acid

The design and synthesis of metal–organic frameworks (MOFs) have attracted much interest due to the intriguing diversity of their architectures and topologies. However, building MOFs with different topological structures from the same ligand is still a challenge. Using 3-nitro-4-(pyridin-4-yl)benzoic acid (HL) as a new ligand, three novel MOFs, namely poly[[(N,N-dimethylformamide-κO)bis[μ2-3-nitro-4-(pyridin-4-yl)benzoato-κ3 O,O′:N]cadmium(II)] N,N-dimethylformamide monosolvate methanol monosolvate], {[Cd(C12H7N2O4)2(C3H7NO)]·C3H7NO·CH3OH} n , (1), poly[[(μ2-acetato-κ2 O:O′)[μ3-3-nitro-4-(pyridin-4-yl)benzoato-κ3 O:O′:N]bis[μ3-3-nitro-4-(pyridin-4-yl)benzoato-κ4 O,O′:O′:N]dicadmium(II)] N,N-dimethylacetamide disolvate monohydrate], {[Cd2(C12H7N2O4)3(CH3CO2)]·2C4H9NO·H2O} n , (2), and catena-poly[[[diaquanickel(II)]-bis[μ2-3-nitro-4-(pyridin-4-yl)benzoato-κ2 O:N]] N,N-dimethylacetamide disolvate], {[Ni(C12H7N2O4)2(H2O)2]·2C4H9NO} n , (3), have been prepared. Single-crystal structure analysis shows that the CdII atom in MOF (1) has a distorted pentagonal bipyramidal [CdN2O5] coordination geometry. The [CdN2O5] units as 4-connected nodes are interconnected by L − ligands to form a fourfold interpenetrating three-dimensional (3D) framework with a dia topology. In MOF (2), there are two crystallographically different CdII ions showing a distorted pentagonal bipyramidal [CdNO6] and a distorted octahedral [CdN2O4] coordination geometry, respectively. Two CdII ions are connected by three carboxylate groups to form a binuclear [Cd2(COO)3] cluster. Each binuclear cluster as a 6-connected node is further linked by acetate groups and L − ligands to produce a non-interpenetrating 3D framework with a pcu topology. MOF (3) contains two crystallographically distinct NiII ions on special positions. Each NiII ion adopts an elongated octahedral [NiN2O4] geometry. Each NiII ion as a 4-connected node is linked by L − ligands to generate a two-dimensional network with an sql topology, which is further stabilized by two types of intermolecular OW—HW...O hydrogen bonds to form a 3D supramolecular framework. MOFs (1)–(3) were also characterized by powder X-ray diffraction, IR spectroscopy and thermogravimetic analysis. Furthermore, the solid-state photoluminescence of HL and MOFs (1) and (2) have been investigated. The photoluminescence of MOFs (1) and (2) are enhanced and red-shifted with respect to free HL. The gas adsorption investigation of MOF (2) indicates a good separation selectivity (71) of CO2/N2 at 273 K (i.e. the amount of CO2 adsorption is 71 times higher than N2 at the same pressure).

Metal-dependent photocatalytic activity and magnetic behaviour of a series of 3D Co–Ni metal organic frameworks

Mixed-metal systems in MOFs modulate their photocatalytic activity and magnetic behavior, which may open a new avenue for the preparation of functional materials with adjustable magnetic behaviors.

Exploration of catecholase-like activity of a series of magnetically coupled transition metal complexes of Mn, Co and Ni: new insights into the solution state behavior of Mn complexes

Oxidation state dependent catecholase activity has been explored with Mn-Schiff-base complex which transform oxidation state from +ii to +iii in solution with time by combined experimental and theoretical investigations.

Developing a magnetic metal organic framework of copper bearing a mixed azido/butane-1,4-dicarboxylate bridge: magnetic and gas adsorption properties

A magnetic metal organic framework {[Cu(but-1,4-dc)0.5(N3)(H2O)]·H2O}n (MFUM-1(Cu)) (but-1,4-dc = butane-1,4-dicarboxylate) was synthesized and characterized structurally and magnetically. In MFUM-1(Cu), each CuII ion has a distorted octahedral geometry with an obvious Jahn-Teller distortion, where the coordination environment is composed of mixed EO-azido/aliphatic based carboxylate/H2O threefold bridges. These bridges extend the structure of MFUM-1(Cu) in two dimensions by covalent connectivity and form square-shaped channels. Also, a study was done to determine the effectiveness of sonochemical synthesis for the preparation of nano-sheets of MFUM-1(Cu) and subsequently the influence of particle size on physical properties such as magnetic behavior and thermal stability. The particles were characterized by elemental analyses, infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD) analyses. The effects of parameters such as concentration, solvent, and reaction time on the size distribution, morphology, and yield of product were carefully studied. The magnetic properties of MFUM-1(Cu) and corresponding nano-structure were examined which indicated metamagnetism with strong intrachain ferromagnetic coupling versus the weak interchain antiferromagnetic coupling. Finally, the application of MFUM-1(Cu) in the separation of carbon dioxide from nitrogen and also from methane was theoretically investigated. High calculated selectivity of CO2 over N2 and CH4 reveals the potential application of MFUM-1(Cu) in practical systems of gas separation.

A two-dimensional copper(II) coordination polymer based on 2,4′-oxybis(benzoate) and 4,4′-bipyridine

The reaction of Cu(NO3)2·3H2O with 2,4′-oxybis(benzoic acid) and 4,4′-bipyridine under hydrothermal conditions produced a new mixed-ligand two-dimensional copper(II) coordination polymer, namely poly[[(μ-4,4′-bipyridine-κ2 N,N′)[μ-2,4′-oxybis(benzoato)-κ4 O 2,O 2′:O 4,O 4′]copper(II)] monohydrate], {[Cu(C14H8O5)(C10H8N2)]·H2O} n , which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. The X-ray diffraction crystal structure analysis reveals that the CuII ions are connected to form a two-dimensional wave-like network through 4,4′-bipyridine and 2,4′-oxybis(benzoate) ligands. The two-dimensional layers are expanded into a three-dimensional supramolecular structure through intermolecular O—H...O and C—H...O hydrogen bonds. Furthermore, magnetic susceptibility measurements indicate that the complex shows weak antiferromagnetic interactions between adjacent CuII ions.

Highly Selective Bifunctional Luminescent Sensor toward Nitrobenzene and Cu2+ Ion Based on Microporous Metal-Organic Frameworks: Synthesis, Structures, and Properties

Two metal-organic frameworks (MOFs), namely, [Ni(DTP)(H₂O)]_n (I) and [Cd₂(DTP)₂(bibp)_1.5]_n (II) (H₂DPT = 4'-(4-(3,5-dicarboxylphenoxy) phenyl)-4,2':6',4″-terpyridine; bibp = 1,3-di(1H-imidazol-1-yl)propane), that present structural diversity were solvothermally prepared. Single-crystal X-ray diffraction analysis indicates that they consist of {NiN₂O₄} building units (for I) and {CdO₄N₂} and {CdO₃N₃} building units (for II), which are further linked by multicarboxylate H₂DPT to construct microporous three-dimensional frameworks. The remarkable character of these frameworks is that coordination polymer II demonstrates highly selective and sensitive bifunctional luminescent sensor toward nitrobenzene and Cu²⁺ ion. The fluorescence quenching mechanism of II caused by nitrobenzene is ascribed to electron transfer from electron-rich (II) to electron-deficient nitrobenzene. The result was also evidenced by the density functional theory. Furthermore, anti-ferromagnetic as well as electrochemical characters of Ni-MOF (I) were also investigated in this paper.

Embedding 1D or 2D cobalt–carboxylate substrates in 3D coordination polymers exhibiting slow magnetic relaxation behaviors: crystal structures, high-field EPR, and magnetic studies

A novel 3D coordination polymer containing 2D cobalt–carboxylate layer had been constructed, exhibiting slow magnetic relaxation.

Crystal structure, solvothermal synthesis, thermogravimetric studies and DFT calculations of a five-coordinate cobalt(II) compound based on the N,N-bis-(2-hy-droxy-eth-yl)glycine anion

The reaction of CoCl2·6H2O, N,N-bis-(2-hy-droxy-eth-yl)glycine and tri-ethyl-amine (Et3N) in ethanol solution under solvothermal conditions produced crystals of [N,N-bis-(2-hy-droxy-eth-yl)glycinato]chloridocobalt(II), [Co(C6H12NO4)Cl]. The CoII ion is coordinated in a slightly distorted trigonal-bipyramidal environment which is defined by three O atoms occupying the equatorial plane and the N and Cl atoms in the apical sites. In the crystal, two types of O-H⋯O hydrogen bonds connect the mol-ecules, forming a two-dimensional network parallel to (001). The mol-ecular structure of the title compound confirms the findings of FTIR, elemental analysis, ESI-MS analysis and TG analysis. By using the density functional theory (DFT) (B3LYP) method with 6-31G(d) basis set, the molecular structure has been calculated and optimized.

Three Cluster Organic Frameworks Constructed from Tetranuclear Cluster Units: Structure and Properties

By treating a semirigid 5-oxyacetate isophthalic acid (H₃ OAIP) ligand with MnSO₄ /CoSO₄ /CdSO₄ under solvothermal conditions, three isostructural cluster organic frameworks, [M₂ (OH)(OAIP)(DMA)]⋅H₂ O (M=Mn²⁺ (1), Co²⁺ (2), Cd²⁺ (3); DMA=N,N'-dimethylacetamide) were constructed. The three complexes contain novel eight-connected tetranuclear M₄ (OH)₂ (COO)₆ (OCH₂ COO)₂ clusters with the unique hexagonal bipyramidal configuration, which are extended by four-connected OAIP linkers to form an uncommon (4,8)-connected alb-4,8-Cmce topology based on (3,6)-connected kgd sublayers. Both 1 and 2 showed significant antiferromagnetic interactions between the intracluster metal ions, whereas 3 revealed strong blue photoluminescence.

Synthesis, structure, magnetic and biological activity studies of bis-hydrazone derived Cu(ii) and Co(ii) coordination compounds

Four coordination compounds of formulae [Cu(II)2(H2L(1))(HL(1))](ClO4)3·H2O (1), [Cu(II)2(H2L(2))(CH3OH)2](ClO4)2·2CH3OH (2), [Co(II)2(H2L(1))2](ClO4)4 (3) and [Co(II)2(H2L(2))2]·2H2O (4) were synthesized via self-assembly of succinohydrazone derived ligands (H2L(1) = N',N'-4-bis(2-pyridyl)succinohydrazide, H4L(2) = N',N'-4-bis(2-hydroxybenzylidene)succinohydrazide) and Cu(2+) and Co(2+) ions, respectively. The compounds were characterized by crystal structure determination, magnetic measurements and biological activities. Compounds 1, 3 and 4 have discrete double helicate structures, whereas compound 2 is a one-dimensional chain. Magnetic studies show antiferromagnetic exchange interactions in 2 with a J value of -67.1 cm(-1) and antiferromagnetic spin-canting in compound 3 originates through supramolecular H-bonding. For compound 3, a clear bifurcation was observed in zero field cooled (ZFC) and field cooled (FC) measurement at a temperature of 3.5 K and field of 0.1 T, implying long range magnetic ordering below this temperature. Interestingly, all of compounds 1-4 show significant changes in their absorption (hypo- and hyperchromism) in the presence of SS-DNA, inferring interaction between the compounds and DNA. In addition, compounds 1-4 significantly exhibited nuclease activities on both RNA and pUC19 plasmid DNA. Moreover, the nuclease activity was further enhanced in the presence of oxidant (H2O2) and suggests the possible role of reactive oxygen species in DNA nicking ability of compounds 1-4. Furthermore, compounds 1, 2 and 4 exhibited significant cytotoxicity against mammalian cancer cell lines (HeLa, A549 and MDAMB-231). In addition, our results from Annexin/PI staining and DNA fragmentation assays revealed that these compounds are capable of inducing apoptosis and have potential to act as anticancer drugs.

The construction, structures, and functions of pillared layer metal–organic frameworks

Pillared layer metal–organic frameworks (PL-MOFs), belonging to one representative of porous materials, have witnessed major advances in the past few years.

A homochiral magnet based on D3 symmetric [(NaO3)Co3] clusters: from spontaneous resolution to absolute chiral induction

A pair novel 3D chiral magnets have been synthesized using the achiral ligand imidazole-4-acrylate via spontaneous resolution, in which the D₃ symmetric chiral [(NaO₆)Co₃] clusters act as nodes. By using chiral induction agent, they are driven to controllable homochiral crystals.

The effect of metal ions on photocatalytic performance based on an isostructural framework

The different central metal ions in CPs have a variety of electronic configurations, which can produce a great impact on the photocatalytic properties.

Template controlled synthesis of cluster-based porous coordination polymers: crystal structure, magnetism and adsorption

By utilizing the template agent, pentaerythritol, a porous framework with dual tetra-nuclear codes has been successfully constructed, which also exhibits interesting magnetism and sorption properties.

The concept of mixed organic ligands in metal–organic frameworks: design, tuning and functions

The mixed organic ligand strategy is significant for the rational construction of MOFs, and furthermore for their functionality and tunability.

Nanoscopic molecular magnets

This review highlights fundamental concepts and synthetic strategies of SMMs and selected examples of 3d, 4f, 5f and mixed 3d–4f, 4d–5d and 3d–5f based SMMs are discussed.

Recent advances in metal–organic frameworks based on pyridylbenzoate ligands: properties and applications

In this mini-review we discuss the properties and applications of metal–organic frameworks based on pyridylbenzoate.

A one-dimensional cobalt(II) coordination polymer based on 2,4'-oxydibenzoic acid: poly[[[diaquabis[2-(4-carboxyphenoxy)benzoato-κO(1)]cobalt(II)]-μ-4,4'-bipyridine-κ(2)N:N'] dihydrate]

The reaction of CoSO4 with 2,4-oxydibenzoic acid (H2oba) and 4,4'-bipyridine (bipy) under hydrothermal condition yielded a new one-dimensional cobalt(II) coordination polymer, {[Co(C14H9O5)2(C10H8N2)(H2O)2]·2H2O}n, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, magnetic properties and single-crystal X-ray diffraction. The Co(II) ions are connected by bipy ligands into infinite one-dimensional chains. The Hoba(-) ligands extend out from the two sides of the one-dimensional chain. O-H···O hydrogen bonding extends these chains into a two-dimensional supramolecular architecture.

A series of divalent metal coordination polymers based on isomeric tetracarboxylic acids: synthesis, structures and magnetic properties

A series of M(ii) coordination polymers has been synthesized. 1–3 contain 1D infinite chains, and these 1D chains are further linked by hydrogen bonding to form 3D supramolecular networks. While 4 and 5 show tetra- or penta-nodal 3D network, respectively.