The preparation of CdO nanowires from solid-state transformation of a layered metal-organic framework

A new coordination polymer formulated as [C₈H₁₀CdO₇]_n·4H₂O has been prepared via a hydrothermal procedure by using 1,4-benzenedicarboxylic (p-BDC) and Cd^II salt as starting materials. The structure was determined by single-crystal X-ray diffraction and the result shows that the complex crystallizes in orthorhombic system, space group Pcca, with M_r=402.62, a=7.293(2) Å, b=9.980(3) Å, c=19.889(6) Å, V=1447.6(8) Å³, Z=4, D_c=1.847 g/cm³, F(000)=808, μ(MoKα)=1.559 mm⁻¹, R=0.0478, wR=0.1150, GOF=1.199. It displays a neutral layered framework along ab plane constructed by hydrogen-bonding interaction through infinite zigzag chains. Its thermal decomposition and solid-state transformation course between 30 and 550 °C was recorded by TG curve and XRD pattern, respectively. Interestingly, it is found that at higher temperature the crystal material was converted to uniform CdO nanowires, suggesting an effective and reasonable complex-precursor procedure for preparing one-dimensional crystalline nanomaterials.     

A highly porous interpenetrated metal-organic framework from the use of a novel nanosized organic linker

The initial use of a novel elongated tricarboxylic acid H(3)hmpib in metal-organic framework (MOF) chemistry resulted in a [Zn(4)O(hmpib)(2)] MOF (UCY-1) with pyrite topology. The compound displays a remarkably high internal surface area despite its double-interpenetrated structure as well as high CO(2) uptake and selective adsorption for it over CH(4).     

A designed metal-organic framework based on a metal-organic polyhedron

A C(3) symmetric ligand with three 1,3-benzenedicarboxylate units has been used to construct a metal-organic framework with a (3,24)-connected network topology, where the nanometre-sized metal-organic cuboctahedra (MOCs) have been incorporated solely into a cubic close packing (CCP) arrangement, which led to superoctahedral and supertetrahedral cavities.     

Novel photocatalysts for the decomposition of organic dyes based on metal-organic framework compounds

Three novel metal-organic frameworks (MOFs) [Co(2)(C(10)H(8)N(2))][C(12)H(8)O(COO)(2)](2), 1, [Ni(2)(C(10)H(8)N(2))(2)][C(12)H(8)O(COO)(2)](2).H(2)O, 2, and [Zn(2)(C(10)H(8)N(2))][C(12)H(8)O(COO)(2)](2), 3, with three-dimensional structures have been synthesized and characterized. The structures of the three compounds appear somewhat related, formed by the connectivity involving the metal polyhedra (Co(4)N trigonal bipyramids in 1, NiO(4)N(2) octahedra in 2, and ZnO(4) tetrahedra and ZnO(3)N(2) trigonal bipyramids in 3), 4,4'-oxybis(benzoate), and 4,4'-bipyridine. The photocatalytic studies on 1-3 indicate that they are active catalysts for the degradation of orange G, rhodamine B, Remazol Brilliant Blue R and methylene blue. The compounds have also been characterized by powder X-ray diffraction, IR, thermogravitmetric analysis, UV-vis, photoluminescence, and magnetic studies.     

Flexible sorption and transformation behavior in a microporous metal-organic framework

Crystals of the metal-organic framework material Ni(2)(4,4'-bipyridine)(3)(NO(3))(4) (A) have been grown by reaction of Ni(NO(3))(2).6H(2)O and 4,4'-bipyridine in methanol solution. Single-crystal X-ray diffraction experiments show that the ladder structure of the framework is maintained after desolvation of the material, resulting in the production of a porous solid stable to 215(4) degrees C. Powder X-ray diffraction has been employed to confirm the bulk purity and temperature stability of this material. The crystal structure indicates that the pore window has an area of 12.3 A(2). However, sorption experiments show these windows will admit toluene, which has a minimum cross-sectional area of 26.6 A(2), with no significant change in the structure. Monte Carlo docking calculations show that toluene can be accommodated within the large pores of the structure. Exposure of the related microporous material Ni(2)(4,4'-bipyridine)(3)(NO(3))(4).2C(2)H(5)OH (B) to methanol vapor causes a guest-driven solid-state transformation to A which is observed using powder X-ray diffraction. This structural rearrangement proceeds directly from crystalline B to crystalline A and is complete in less than 1 day. Mechanisms for the transformation are proposed which require breaking of at least one in six of the covalent bonds that confer rigidity on the framework.     

Stepwise assembly of metal-organic framework based on a metal-organic polyhedron precursor for drug delivery

A 12-connected network with fcu topology was firstly reported focusing on using predesigned metal-organic polyhedron (MOP) as the precursor, and its adsorption and delivery of the drug 5-fluorouracil (5-FU) was also determined.     

A two-component polymeric optode membrane based on a multifunctional ionic liquid

This work details the use of a 2-component optode membrane which is capable of generating three distinct colours in the presence of Cu(2+) and Co(2+) ions. It has been found that the ionic liquid (IL) trihexyltetradecylphosphonium dicyanamide [P(6,6,6,14)][DCA] can act as plasticizer, ligand and transducer dye when used in poly(vinyl chloride) (PVC) membranes, which significantly simplifies the optode membrane cocktail. Upon exposure to an aqueous Cu(2+) solution, a yellow colour is generated within the membrane, while exposure to an aqueous Co(2+) solution generates a blue colour. Exposure to a solution containing both ions produces a green colour. Vibrational spectroscopy has been used to investigate the molecular basis of the IL-metal ion the binding mechanism. Analytical characteristics of the membranes including the effect of interfering ions, binding constants and the limit of detection for both ions have been estimated. Finally the case of simultaneous dual-analyte recognition is presented based on two distinct absorption maxima.     

Thermal expansion-quench of nickel metal-organic framework into nanosheets for efficient visible light CO2 reduction

Metal-organic framework nanosheets (MOF NNs) offer potential opportunities for many applications,but an efficient strategy for the scalable preparation of few-layered two-dimensional (2D) MOF NNs are still a major challenge.Herein,we present an efficient top-down method for the synthesis of the Ni-BDC(Ni₂(OH)₂(1,4-BDC);1,4-BDC=1,4-benzenedicarboxylate) nanosheets utilizing a novel thermal expansionquench method of the flowerlike bulky MOFs in liquid N₂.The obtain...     

A new layered metal-organic framework as a promising heterogeneous catalyst for olefin epoxidation reactions

A new layered MOF material [Co(Hoba)(2)·2H(2)O] (1) (H(2)oba = 4,4'-oxybis(benzoic acid)) has been synthesized and used as a highly recyclable heterogeneous catalyst for olefin epoxidation reactions. Both high conversion (96%) and high selectivity of epoxide products (96%) are achieved.     

Assembly of super-supertetrahedral metal-organic clusters into a hierarchical porous cubic framework

A porous framework comprising a super-supertetrahedral metal-organic cluster building block has been synthesized. Its cubic framework represents a multi-level hierarchical architecture and also possesses an interesting magnetic property.     

Metal–organic framework assembled from erbium and a tetrapodal polyphosphonic acid organic linker

A three‐dimensional metal–organic framework (MOF), poly[[μ₆‐5′‐pentahydrogen [1,1′‐biphenyl]‐3,3′,5,5′‐tetrayltetrakis(phosphonato)]erbium(III)] 2.5‐hydrate], formulated as [Er(C₁₂H₁₁O₁₂P₄)]·2.5H₂O or [Er(H₅btp)]·2.5H₂O ( I ) and isotypical with a Y³⁺‐based MOF reported previously by our research group [Firmino et al. (2017b). Inorg. Chem. 56 , 1193–1208], was constructed based solely on Er³⁺ and on the polyphosphonic organic linker [1,1′‐biphenyl]‐3,3′,5,5′‐tetrakis(phosphonic acid) (H₈btp). The present work describes our efforts to introduce lanthanide cations into the flexible network, demonstrating that, on the one hand, the compound can be obtained using three distinct experimental methods, i.e. hydro(solvo)thermal (Hy), microwave‐assisted (MW) and one‐pot (Op), and, on the other hand, that crystallite size can be approximately fine‐tuned according to the method employed. MOF I contains hexacoordinated Er³⁺ cations which are distributed in a zigzag inorganic chain running parallel to the [100] direction of the unit cell. The chains are, in turn, bridged by the anionic organic linker to form a three‐dimensional 6,6‐connected binodal network. This connectivity leads to the existence of one‐dimensional channels (also running parallel to the [100] direction) filled with disordered and partially occupied water molecules of crystalization which are engaged in O—H…O hydrogen‐bonding interactions with the [Er(H₅btp)] framework. Additional weak π–π interactions [intercentroid distance = 3.957 (7) Å] exist between aromatic rings, which help to maintain the structural integrity of the network.     

Influence of organic bases on constructing 3D photoluminescent open metal-organic polymeric frameworks

Four three-dimensional non-interpenetrating open coordination frameworks constructed from the CTC ligand (CTC =cis,cis-1,3,5-cyclohexanetricarboxylate) coordinated to metal ions (Mn(II) and Cd(II)): Mn(3)(CTC)(2)(DMF)(2)(1); Cd(3)(CTC)(2)(H(2)O)(3).H(2)O (2); Cd(3)(CTC)(2)(4,4'-bpy)(2)(EG)(2)(3); Cd(3)(CTC)(2)(mu(2)-hmt)(DMF)(C(2)H(5)OH)(H(2)O).2H(2)O (4)(DMF = dimethylformamide and EG = ethylene glycol) have been synthesized by slow evaporation of DMF-C(2)H(5)OH-H(2)O solutions of M(II)(Mn(II) or Cd(II)) and CTC in the presence of the organic bases TEA (triethylamine), TEA, 4,4'-bpy (4,4'-bipyridine) and hmt (hexamethylenetetramine), respectively, and structurally characterized by X-ray crystallography. The polymer constructed by CTC and Mn(II) exhibits a 3-D architecture with 5 x 9 A channels; the polymer formed by CTC and Cd(II) exists a 3-D extended framework with 9 x 9 A channels; wave-like sheet subunits of the polymer are upheld by 4,4'-bpy ligands resulting in a 3-D framework with 4 x 10 A channels; two-fold alternate sheet subunits of the polymer are interlinked by mu(2)-hmt ligands to form a novel 3-D architecture with 7 x 8 A channels. Polymers exhibit their strongest excitation peaks at 391, 390 and 394 nm, respectively, and their main strong emission peaks are at 543, 460 (with a shoulder peak at about 570 nm) and 557 nm, respectively.     

Hydroxyl group recognition by hydrogen-bonding donor and acceptor sites embedded in a layered metal-organic framework

One of the dominant types of interactions between host and guest molecules is hydrogen-bonding, and these interactions can work selectively for a guest molecule. Here, we demonstrate a metal-organic framework (MOF) having both hydrogen-bonding donor and acceptor sites that are quite effective for selective sorption. The MOF selectively interacts with hydroxylic guests in contrast to aprotic hydrogen-bonding guests and shows a sorption selectivity for protic H(2)O, MeOH, and EtOH guests. Notably, this is the first compound that shows complete selectivity in adsorption not for MeCN and MeCHO but for EtOH, which has similar fundamental properties except for its proticity.     

Thermal transformation of solid organic compounds

The thermal decomposition of malonic acid was investigated with a derivatograph. Values of activation energy, frequency factor and reaction order were determined from thermal decomposition curves employing different calculation methods. Equations derived for the calculation of kinetic data of inorganic thermal reactions were also found to be suitable in the case of organic reactions. Convenient methods were developed for the calculation of the activation energy, using the DTG curve.     

Solvent-induced single-crystal to single-crystal transformation of a 2D coordination network to a 3D metal-organic framework greatly enhances porosity and hydrogen uptake

Exposure to CH(2)Cl(2) at room temperature induces single-crystal to single-crystal transformation of the 2D coordination network [Zn(2)L(DMF)(4)]·2DMF·4H(2)O to the 3D metal-organic framework [Zn(2)L(H(2)O)(2)]·xsolv via dimerization of the metal-connecting points, leading to significant enhancement in framework stability, porosity, and H(2) uptake capacity.