NbO Topology Research Articles

Enhanced CO2 Adsorption Affinity in a NbO-type MOF Constructed from a Low-Cost Diisophthalate Ligand with a Piperazine-Ring Bridge.

A metal-organic framework (NPC-6) with an NbO topology based on a piperazine ring-bridged diisophthalate ligand was synthesized and characterized. The incorporated piperazine group leads to an enhanced adsorption affinity for CO2 in NPC-6, in which the CO2 uptake is 4.83 mmol g(-1) at 293 K and 1 bar, ranking among the top values of CO2 uptake on MOF materials. At 0.15 bar and 293 K, the NPC-6 adsorbs 1.07 mmol g(-1) of CO2 , which is about 55.1 % higher than that of the analogue MOF NOTT-101 under the same conditions. The enhanced CO2 uptake combined with comparable uptakes for CH4 and N2 leads to much higher selectivities for CO2 /CH4 and CO2 /N2 gas mixtures on NPC-6 than on NOTT-101. Furthermore, an N-alkylation is used in the synthesis of the PDIA ligand, leading to a much lower cost compared with that in the synthesis of ligands in the NOTT series, as the former does not require a palladium-based catalyst and borate esters. Thus, we conclude that NPC-6 is a promising candidate for CO2 capture applications.

Clathration of Five-Membered Aromatic Rings in the Bimetallic Spin Crossover Metal–Organic Framework [Fe(TPT)2/3{MI(CN)2}2]·G (MI = Ag, Au)

Six clathrate compounds of the three-dimensional spin crossover metal–organic framework formulated [Fe(TPT)2/3{MI(CN)2}2]·nG, where TPT is 2,4,6-tris(4-pyridyl)-1,3,5-triazine, MI = Ag or Au and G represent the guest molecules furan, pyrrole and thiophene, were synthesized using slow diffusion techniques. The clathrate compounds were characterized by single-crystal X-ray diffraction at 120 and 300 K, thermogravimetric analysis and thermal dependence of the magnetic susceptibility. All compounds crystallize in the R3̅m trigonal space group. The FeII defines a unique [FeN6] crystallographic site with the equatorial positions occupied by four dicyanometallate ligands while the axial positions are occupied by the TPT ligands. Each TPT ligand links three FeII sites, while the dicyanometallate ligands bridge two FeII sites thereby generating two interlocked three-dimensional frameworks with the NbO topology. The choice of the TPT ligand favors the generation of pores where the guest molecules are located. The thermal dependence of the magnetic susceptibility of samples constituted of single crystals was investigated for the six compounds to assess the influence of the guest molecules on the spin crossover behavior. In general, the magnetic properties of the six clathrates suggest a gradual stabilization of the high-spin state as the molecular volume of the guest increases.

Inside Back Cover: Cluster Linker Approach: Preparation of a Luminescent Porous Framework with NbO Topology by Linking Silver Ions with Gold(I) Clusters (Angew. Chem. Int. Ed. 47/2014)

Inside Back Cover: Cluster Linker Approach: Preparation of a Luminescent Porous Framework with NbO Topology by Linking Silver Ions with Gold(I) Clusters (Angew. Chem. Int. Ed. 47/2014)

Cluster linker approach: preparation of a luminescent porous framework with NbO topology by linking silver ions with gold(I) clusters.

A cluster-based luminescent porous metal-organic framework has been constructed through a "cluster linker" approach. The luminescent gold(I) cluster, prefunctionalized with pyrazinyl groups, was used as a cluster linker, similar to an organic linker, to connect silver ions in order to form a 3D framework. 1D channels with 1.1 nm diameter were observed in the framework. The cluster with its intrinsic luminescence was incorporated into a porous framework to give a luminescent bifunctional NbO net. This MOF shows solvatochromic behavior, and the interactions between solvent molecules and silver ions inside the channels account for the changes in absorption and emission spectra.

Cluster Linker Approach: Preparation of a Luminescent Porous Framework with NbO Topology by Linking Silver Ions with Gold(I) Clusters

AbstractA cluster‐based luminescent porous metal–organic framework has been constructed through a “cluster linker” approach. The luminescent gold(I) cluster, prefunctionalized with pyrazinyl groups, was used as a cluster linker, similar to an organic linker, to connect silver ions in order to form a 3D framework. 1D channels with 1.1 nm diameter were observed in the framework. The cluster with its intrinsic luminescence was incorporated into a porous framework to give a luminescent bifunctional NbO net. This MOF shows solvatochromic behavior, and the interactions between solvent molecules and silver ions inside the channels account for the changes in absorption and emission spectra.

Synthesis and characterizations of two NbO topological gallium phosphites with low framework density

Two new 3D open-framework gallium phosphites Ga(HPO3)F2·(H2A)0.5, where A=C5N2H12(1) and C6N2H14 (2) have been solvothermally synthesized in the presence of 2-methyl piperazine and N,N′-dimethyl piperazine as template, respectively. Single crystal X-ray diffraction reveals that these two compounds have the similar inorganic framework structures, which may be viewed as the assembly of a second building unit (SBU), Ga2F2O4(HPO3)2 containing one dimer Ga2F2O8 and two HPO3 groups. The SBUs are linked with each other via vertex-sharing oxygen atoms to form a new 3D open-framework which possesses the left- and right-handed helical chains along c axis. With the SBU as 4-connected nodes, the structure can be simplified into a uninodal NbO topology. Moreover, compounds 1 and 2 show low framework density value of 9.4 and 9.7, respectively. Crystal data: compound 1, Trigonal, R-3 (148), a=b=18.315(3)Å, c=13.136(4)Å, γ=120°, V=3815.9(13)Å3 and Z=9; compound 2, Trigonal, R-3 (148), a=b=17.8476(4)Å, c=13.5159(6)Å, γ=120°, V=3728.5(2)Å3 and Z=18.

Crystal Engineering of an nbo Topology Metal–Organic Framework for Chemical Fixation of CO2 under Ambient Conditions

AbstractCrystal engineering of the nbo metal–organic framework (MOF) platform MOF‐505 with a custom‐designed azamacrocycle ligand (1,4,7,10‐tetrazazcyclododecane‐N,N′,N′′,N′′′‐tetra‐p‐methylbenzoic acid) leads to a high density of well‐oriented Lewis active sites within the cuboctahedral cage in MMCF‐2, [Cu2(Cu‐tactmb)(H2O)3(NO3)2]. This MOF demonstrates high catalytic activity for the chemical fixation of CO2 into cyclic carbonates at room temperature under 1 atm pressure.

Crystal Engineering of an nbo Topology Metal–Organic Framework for Chemical Fixation of CO2 under Ambient Conditions

Crystal engineering of the nbo metal-organic framework (MOF) platform MOF-505 with a custom-designed azamacrocycle ligand (1,4,7,10-tetrazazcyclododecane-N,N',N'',N'''-tetra-p-methylbenzoic acid) leads to a high density of well-oriented Lewis active sites within the cuboctahedral cage in MMCF-2, [Cu2(Cu-tactmb)(H2O)3(NO3)2]. This MOF demonstrates high catalytic activity for the chemical fixation of CO2 into cyclic carbonates at room temperature under 1 atm pressure.

A nitro-decorated NbO-type metal–organic framework with a highly selective CO2 uptake and CH4 storage capacity

A nitro-decorated and highly porous metal–organic framework with NbO topology was reported, exhibiting good adsorption selectivity of CO2/CH4 (8) and CO2/N2 (24) at 273 K and 1 bar, high methane total uptake of 184 cm3 cm−3 at 290 K and 35 bar.

Three‐Dimensional Porous NbO‐Type Anionic Framework: Synthesis, Structure, Magnetic and Adsorption Properties

AbstractAbstract. Three‐dimensional porous framework {[Ni3(BPTCA)2(H2O)2][Ni(H2O)6]·10H2O}n (1) was synthesized by using the 4, 4′‐bipyridine‐2, 2′6, 6′‐tetracarboxylic acid anion (BPTCA–4) as building block under hydrothermal conditions. The structural analysis revealed this complex has a NbO topology. Unexpectedly, 1 has an anionic framework with 10.9 × 8.7 Å rectangle channels, and the cationic [Ni(H2O)6]2+ species serve as guest. In addition, thermogravimetric analyses proved 1 can keep its crystalline nature even at 300 °C. The nitrogen adsorption and magnetic properties of 1 were also investigated.

Construction of Six Coordination Polymers Based on a 5,5′-(1,2-Ethynyl)bis-1,3-benzenedicarboxylic Ligand: Synthesis, Structure, Gas Sorption, and Magnetic Properties

Six novel coordination polymers based on a multifunctional ligand, 5,5′-(1,2-ethynyl)bis-1,3-benzenedicarboxylic (H4EBDC), namely, |(C3H7NO)2(H2O)7(C2H5OH)3|[Zn2(C18H6O8)(C10H8N2)2] (1), |(C3H7NO)3(H2O)30(CH3CN)2|[Zn6(C18H6O8)3(C6H12N2O2)2] (2), |(C3H7NO)2(H2O)2(H3O)2|[Cd3(C18H6O8)2] (3), |(C3H7NO)|[Mn(C18H8O8)(C3H7NO)2] (4), |(C3H7NO)2(H2O)(C2H7N)3|[Mn6(C18H7O8)4(H2O)8] (5), and [Mn2(C18H6O8)(C3H7NO)2] (6), have been constructed under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction. In these compounds, the ligand, H4EBDC, exhibits different coordination modes and conformations, constructing various architectures by bridging a variety of metal ions or polynuclear clusters. Compound 1 forms a three-dimensional (3D) FSC network constructed from two-dimensional (2D) layer motifs joined by EBDC4– and 4,4′-bipyridine bridges. Compound 2 possesses an NbO topology by linking Zn2(CO2)4 units with the ligand, coordinated amine molecules fill the pores, while compound 3 ex...

Five new coordination polymers based on a semi-rigid dicarboxylic acid and versatile N-donor ligands: synthesis, characterization and properties

Based on a semi-rigid dicarboxylic acid and N-donor ligands with versatile conformations, five new coordination polymers, namely, [Zn(pdda)(bpy)] (1), [Ni(pdda)(bib)]·H2O (2), [Ni(pdda)(bpp)] (3), [Cd2(pdda)2(bit)(H2O)2] (4) and [Mn4(pdda)4(phen)2]·H2O (5) (H2pdda = 4,4′-(1,3-phenylenedioxy)dibenzoic acid, bpy = 2,2′-bipyridine, bib = 1,4-bis(imidazole)butane, bpp = 1,3-bis(4-pyridyl)propane, bit = 1,4-bis(imidazol-1-ylmethyl)benzene, phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions. Their structures have been characterized by single-crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy and thermogravimetric analysis. Compound 1 shows the interweaving of single helical chains. Compound 2 displays a polycatenane framework with the entanglement of (4,4) layers. Compound 3 exhibits a mutual incorporation of two (4,4) layers. Compound 4 is also a (4,4) layer structure which can be split into interesting double helixes. Compound 5 features a 3D framework of NbO topology. Their photochemical and magnetic properties were measured.

Hysteretic carbon dioxide sorption in a novel copper(ii)-indazole-carboxylate porous coordination polymer

The synthesis, structural and gas sorption studies of a porous Cu(II) coordination polymer featuring 1H-indazole-5-carboxylic acid (H(2)L) are presented. [Cu(HL)(2)] is a thermally and hydrolytically robust 4-connected 3D coordination polymer of NbO topology and is replete with 1D channels that permit selective and hysteretic sorption of CO(2).

Ligand-Directed Construction of Zn(II) Complexes from Zero-Dimensional Metallomacrocycle to One-, Two-, and Three-Dimensional Coordination Polymers Based on N-Donor and β-Diketone Bifunctional Ligands

Six new complexes [Zn2(L1)4]·2H2O·DMF (1), [Zn2(L2)4]3·13H2O (2), [Zn1.5(L3)3]2 (3), Zn(L4)2·2H2O (4), Zn(L5)2·2CHCl3 (5), and [Zn(L6)2]2 (6) (where HL1 = 1-(4-(1H-imidazol-1-yl)phenyl)butane-1,3-dione, HL2 = 1-(4-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione, HL3 = 1-(4-(1H-pyrazol-1-yl)phenyl)butane-1,3-dione, HL4 = 1-(3-(1H-imidazol-1-yl)phenyl)butane-1,3-dione, HL5 = 1-(3-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione and HL6 = 1-(3-(1H-pyrazol-1-yl)phenyl)butane-1,3-dione) have been synthesized by the reaction of the bifunctional ligands and Zn(II) salts under similar experimental conditions. Structural analyses show that the ligands act as a tridentate and bind to two Zn(II) ions as a two-connected linker, generating a variety of geometries from discrete binuclear [2 + 2] metallomacrocycles (3 and 6) to a one-dimensional looped-chain coordination polymer (4) and two-dimensional (4,4) network (5) as well as three-dimensional frameworks with lvt (1) and NbO (2) topologies. The results demonstrate that the diverse structures are strongly dependent on the ligand geometries, due to the free rotation via the C–N/C–C bonds as well as the various coordinated sites of N-donor allowing the semirigidity ligands to take on appropriate conformations.

Cocrystal controlled solid-state synthesis of a rigid tetracarboxylate ligand that pillars both square grid and Kagomé lattice layers

[Cu2(carboxylate)4] paddlewheel molecular building blocks, MBBs, are capable of generating square grid or Kagome lattice supramolecular isomers when dicarboxylates such as 1,3-benzenedicarboxylate (1,3-bdc) and 1,4-benzenedicarboxylate (1,4-bdc) are exploited to link the paddlewheel MBBs. In this contribution we demonstrate that it is possible to use a solvent-free reaction (cocrystal controlled solid-state synthesis) to prepare a tetracarboxylic acid, H44BIPA-TC, formed by rigidly linking two 1,3-bdc moieties at the 5-position. BIPA-TC can pillar both square grid and Kagome lattice supramolecular isomers, thereby generating nets that exhibit lvt or nbo topologies, respectively.

Synthesis, Structure, and Gas Sorption Studies of a Three-Dimensional Metal−Organic Framework with NbO Topology

A new tetracarboxylate ligand with two alkyne functionalities has been synthesized and used to form a three-dimensional (3D) metal−organic framework {[Cu2(BDDC)(H2O)2]·DMF·3H2O}n (H4BDDC = 5,5′-(buta-diyne-1,4-diyl) diisophthalic acid) (DMF = N,N′-dimethylformamide). The single-crystal structure analysis reveals the topology is based on the NbO net, constructed by 4-connected rectangular ligands and 4-connected square Cu2(CO2)4 secondary building units (SBUs). The compound has permanent porosity with a large Langmuir surface area of 3111 m2/g, and shows excess and total H2 uptake as high as 3.98 and 4.60 wt %, respectively, at 77 K and 17 bar.

Structure, Hydrogen Storage, and Luminescence Properties of Three 3D Metal−Organic Frameworks with NbO and PtS Topologies

Three 3D multifunctional microporous metal−organic frameworks (MOFs), Cu2(ABTC)(H2O)2·(DMF)2(H2O) (JUC-62), Cd2(ABTC)(DMF)3·(DMF)2 (JUC-63), and Mn(H2ABTC)(DMF)2 (JUC-64) (H4ABTC = 3,3′,5,5′-azobenzenetetracarboxylic acid, DMF = N,N′-dimethylformamide, and JUC = Jilin University China) have been synthesized by self-assembly of a rigid tetra-carboxylate ligand H4ABTC and corresponding transition metal salts under mild conditions. X-ray crystallography reveals that their topologies are based on NbO (JUC-62) and PtS (JUC-63 and JUC-64) nets, constructed of 4-connected rectangular ABTC4− units with 4-connected square paddle-wheel Cu2(CO2)4(H2O)2 secondary building units (SBUs), tetrahedral bimetallic Cd2(CO2)4(DMF)3 SBUs, and tetrahedral monometallic Mn(CO2)4(DMF)3 SBUs, respectively. High-pressure hydrogen sorption of the activated JUC-62 reveals a type I profile at 77 K, which is saturated at 40 bar with a hydrogen uptake of about 4.71 wt%. Photoluminescence investigations reveal that JUC-62 and JUC-63 disp...

PH-Dependent Assembly of Hybrids Based on Wells-Dawson POM/Ag Chemistry

Four new hybrids based on the Wells-Dawson polyoxometalate [P2W18O62](6-) (P2W18), ([Ag(bipy)]2[P2W18O62]).2[H2bipy].4H2O (1), ([Ag(bipy)]4[P2W18O62]).2[Hbipy](2), K[P2W18O62].2.5[H2bipy].2H2O (3), and [P2W18O62] 2.[H2bipy]4.[Hbipy]4 .3H2O (4), were hydrothermally synthesized and structurally characterized by routine techniques and single-crystal X-ray diffraction. Compounds 1 and 2 are isolated at lower pH values. 1 represents a 3D (4,4)-net structure with NbO topology, in which the P2W18 clusters are modified by four Ag-N coordination polymeric chains, and 2 exhibits a 3D (3,4)-net structure with the (9(2).12)(8.10(4).12)(3(2).10(2).11(2))(3.6.10(2).12(2)) topology, in which Ag-bipy layers are intercalated by the dimer of P2W18 clusters in a staggering mode, and the P2W18 clusters show the highest coordination number to date. By increasing the pH value, compounds 3 and 4 are obtained as supramolecular compounds. Their structural differences reveal that the pH value of the reaction system is the key factor influencing the structure and topology of these compounds, which can be explained by the acid-base chemistry of the molecular building units and silver chemistry.

Coordination polymers undergoing spin crossover and reversible ligand exchange in the solid

Here we report the synthesis and characterisation of a polymer made up of a system of parallel 2-D grids of Fe(II) ions linked by [Au(CN)2]- bridges and its transformation into a new system of three interpenetrated 3-D coordination open frameworks with the NbO topology. Reversibility of this crystal-to-crystal transformation is evidenced by X-ray crystallographic data and from their spin crossover properties.

High H2 Adsorption in a Microporous Metal–Organic Framework with Open Metal Sites

High H₂ Adsorption in a Microporous Metal–Organic Framework with Open Metal Sites