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Storage and purification of light hydrocarbons are very meaningful for their high-purity requirements and safety utilization in the fields of industry and clean energy. It is a simple and effective way to achieve this goal utilizing the physical adsorption properties of stable porous metal-organic frameworks (MOFs). In this work, a stable self-interpenetrated three-dimensional MOF with a new 3,4-connected topology, {[Zn2(tpda)2(4,4'-bpy)]·4DMF}n (NKM-101; H2tpda = 4,4'-[4-(4H-1,2,4-triazol-4-yl)phenyl]dibenzoic acid, 4,4'-bpy = 4,4'-bipyridine, and DMF = N,N-dimethylformamide), has been successfully constructed based on a triazole-carboxyl ligand. The dense functional active sites existing on the inner walls of one-dimensional channels of NKM-101 are beneficial to enhancement of the binding affinities between the framework and specific molecules (CO2, C2-C4). Therefore, the selective adsorption and separation performance of the material on CO2/CH4 and C2-C4/CH4 are effectively improved. In addition, NKM-101 also exhibits excellent water stability, making it possible to be a practical material for the storage and purification of light hydrocarbons.

In spite of the attractive potential application of the dynamic behavior and defect of metal–organic framework (MOF), the achievement of these features is a challenging goal in the MOF research field. Herein, we report a Co­(II) MOF, namely, [Co3(L)2­(4-PTZ)2(H2O)2]n·solvent (H2L = 5-(isonicotinamido)­isophthalic acid, 4-PTZ = 5-(4-pyridyl)-1H-tetrazole), that features dynamic structural transformation behaviors. By varying the coordination configuration of metal center through the removal of coordinated water molecules, the porous compound could undergo structural transformation to give a new crystalline phase with larger pore dimension. Moreover, the new phase features a mesoporous structure originating from the spatial defect that formed with the transformation process, which indicates that the modulation of dynamic behavior of the MOF could be a potential method for the engineering of a spatial defect. In addition, the gas sorption investigation results reveal that the new phase has enhanced selectivity for CO2/N2, CO2/CH4, and C2H2/C2H4 systems compared with that of the pristine phase, suggesting the potential of spatial defect engineering for the tuning of MOF gas sorption properties.

The construction and modulation of hierarchical pore structure in metal-organic frameworks (MOFs) has become a hot topic owing to the advantages of hierarchical pore MOFs (HP-MOFs) in matter storage and mass transfer related applications. Herein, we report the engineering of crystalline defect in a bimetallic MOF for the construction and tuning of HP-MOF. A microporous MOF system showing metal-center-dependent water stability, namely, {[M3F(bdc)3 tpt] (solvents)}n (M = Zn2+ and Ni2+, H2bdc = 1,4-benzenedicarboxylic acid, tpt = 2,4,6-tris(4-pyridyl)triazine), was utilized as a platform for the construction of HP-MOF. By tuning the Zn2+/Ni2+ ratio in the reactant, a bimetallic MOF with a highly tunable Zn2+/Ni2+ ratio could be obtained. The relatively labile Zn2+-based coordination bonding in the bimetallic MOF could be readily and targeted broken through water treatment for the engineering of crystalline defects-based hierarchical pore structure. The resultant HP-MOF reveals a dramatically increased pore volume with the presence of mesopore and macropore. In addition, the anionic framework of HP-MOF could be utilized for the selective adsorption of a cationic dye methylene blue, and a relatively high capacity (250 mg·g-1, five times compared with the pristine microporous MOF) could be achieved.

Metal–organic frameworks (MOFs) with diverse structures, adjustable pore sizes, and high surface areas have exhibited awesome potential in many fields. Here we report a simple carbonization strategy to obtain a series of core–shell structured Co/Co3O4 nanoparticles encapsulated into nitrogen-doped carbon shells from cobalt-based metal–organic framework precursors at different carbonization temperatures. When it is applied as an anodes for lithium ion batteries, the Co/Co3O4@N-C-700 electrode delivers a maximum initial discharge capacity of 1535 mAh g–1, the highest reversible capacity (903 mAh g–1 at a current density of 100 mA g–1 after 100 cycles), and the best rate performance (i.e., 774 mAh g–1 at a current density of 1.0 A g–1 after 100 cycles) in comparison with those of Co/Co3O4@N-C-600 and Co/Co3O4@N-C-800 electrodes. The excellent electrochemical performance could be mainly attributed to the unique core–shell structure, abundant graphited carbon, and the well-dispersed Co/Co3O4 nanoparticles whic...

Four heterometallic formate frameworks templated by various alkylamine cations with the general formula [cat][GaIIIMnII(HCOO)6] {cat is MA (CH3NH3+) for 1, DMA [(CH3)2NH2+] for 2, EtA (CH3CH2NH3+) for 3, and DEtA [(CH3CH2)2NH2+] for 4} have been prepared and characterized by X-ray diffraction, differential scanning calorimetry, and dielectric studies. All of the complexes have niccolite-like structures, which possess the same [GaMn(HCOO)6]- anionic framework with binodal (412·63)(49·66) topology; only the counterions in the cavity are different. Complex 4 undergoes a reversible ferroelastic phase transition around 220 K accompanied by a thermally switchable dielectric constant transition triggered by the freezing of the order-disorder DEtA cations.

CNFs@Co-CoO (CNFs = carbon nanofibers) composite showing "gypsophila"-like morphology was designed and prepared for the first time with in situ grown PAN@ZIF-67 (PAN = polyacrylonitrile) as the precursor. Benefiting from its unique morphology, hierarchically porous structure, and high-activity Co-CoO catalyst centers, the composite shows a better electrochemical performance than pure CNFs as a cathode for Li-O

Metal-organic frameworks (MOFs) with diverse structures, adjustable pore sizes, and high surface areas have exhibited awesome potential in many fields. Here we report a simple carbonization strategy to obtain a series of core-shell structured Co/Co

Water instability is a crucial limiting factor in the practical application of most fluorescent metal-organic frameworks (MOFs). Here, by introducing a fascinating double-helical structure generated through dense stacking of organic ligands, a water-stable fluorescence MOF has been synthesized, namely, [Cd2(tib)2(bda)2]·(solvent)n (1) [tib =1,3,5-tris(1-imidazolyl) benzene; H2bda = 2,2'-biphenyl dicarboxylic acid]. This helical structure helps to enhance the stability of 1 against common organic solvents and water, even acid/base aqueous solutions with a pH value ranging from 3 to 11. Furthermore, this material can be a potential fluorescent sensor for ketones.

Gas storage/separation is a typical application of porous materials such as metal organic frameworks (MOFs). The adsorption/separation behavior results from the host–guest and/or guest–guest interaction and equilibration (host, porous material; guest, adsorbates). Although the driving forces for gas adsorption have been investigated, a detailed picture of interactions between gas molecules and MOFs has not clearly emerged. Herein, a new cobalt microporous MOF [Co(tipb)(adc)](DMF)3(H2O)1.5, which possesses a rare self-interpenetrated gra topology, has been prepared with both tipb and H2adc ligands (tipb = 1,3,5-tris(p-imidazolylphenyl)benzene, adc = 9,10-anthracenedicarboxylate). This MOF shows high stability and exceptional selective adsorption of CO2 over N2, O2, and CH4. In particular, a theoretical assumption of a “regional dynamic electric field effect” is proposed to clarify the selective adsorption. Moreover, we suggest that the proposed effect may be one of the most important factors impacting gas ...

Two new zinc MOFs with similar “pillar-layered” framework structures based on 1,1′-biphenyl-2,2′,6,6′-tetracarboxylic acid (H4bpta) and two different bipyridine pillar ligands, namely {[Zn4(bpta)2(4-pna)2(H2O)2]·4DMF·3H2O}n (1) and {[Zn2(bpta)(bpy-ea)(H2O)]·2DMF·H2O}n (2) (4-pna = N-(4-pyridyl)isonicotinamide and bpy-ea = 1,2-bis(4-pyridyl)ethane), have been synthesized and investigated with their CO2 adsorption properties. By analysis of the structure properties and the CO2 adsorption performances of these two MOFs, it was found that the introduction of polar acylamide groups via 4-pna resulted in 1 with enhanced CO2 capacity and CO2/CH4 selectivity at low pressure. In contrast, the framework of 2 shows flexible properties originating from the flexibility of the ethanediylidene group in the bpy-ea ligand, which benefits the sieve effect of pores to give higher CO2/CH4 selectivity at a relatively high pressure range.

A study of the magnetic structure of the [NH2(CH3)2]n[FeIIIMII(HCOO)6]n niccolite-like compounds, with MII = CoII (2) and MnII (3) ions, has been carried out using neutron diffraction and compared with the previously reported FeII-containing compound (1). The inclusion of two different metallic atoms into the niccolite-like structure framework leads to the formation of isostructural compounds with very different magnetic behaviors due to the compensation or not of the different spins involved in each lattice. Below TN, the magnetic order in these compounds varies from ferrimagnetic behavior for 1 and 2 to an antiferromagnetic behavior with a weak spin canting for 3. Structure refinements of 2 and 3 at low temperature (45 K) have been carried out combining synchrotron X-ray and high-resolution neutron diffraction in a multipattern approach. The magnetic structures have been determined from the difference patterns between the neutron data in the paramagnetic and the magnetically ordered regions. These difference patterns have been analyzed using a simulated annealing protocol and symmetry analysis techniques. The obtained magnetic structures have been further rationalized by means of ab initio DFT calculations. The direction of the magnetic moment of each compound has been determined. The easy axis of the MII for compound 1 (FeII) is along the c axis; for compound 2 (CoII), the moments are mainly within the ab plane; finally, for compound 3 (MnII), the calculations show that the moments have components both in the ab plane and along the c axis., Partial funding for this work is provided by the Ministerio Español de Ciencia e Innovacion through projects MAT2011-27233-C02-02 and MAT2011-25991 and Centro Universitario de la Defensa de Zaragoza through CUD 2013-17. J.A.R.V. acknowledges CSIC for a JAEdoc contract.

In our efforts toward rational design and systematic synthesis of 'pillar-layer' structure MOFs, three porous MOFs have been constructed based on [Zn(4)(bpta)(2)(H(2)O)(2)] (H(4)bpta = 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid) layers and three different bipyridine pillar ligands. The resulted MOFs show similar structures but different pore volume and window size depending on the length of pillar ligands which resulted in distinct gas adsorption properties. In the three MOFs, [Zn(4)(bpta)(2)(4,4'-bipy)(2)(H(2)O)(2)]·(DMF)(3)·H(2)O (1) (DMF = N,N'-dimethylformamide and 4,4'-bipy = 4,4'-bipyridine) reveals selective adsorption of H(2) over N(2) and O(2) as the result of narrow pore size. [Zn(4)(bpta)(2)(azpy)(2)(H(2)O)(2)]·(DMF)(4)·(H(2)O)(3) (2) and [Zn(4)(bpta)(2)(dipytz)(2)(H(2)O)(2)]·(DMF)(4)·H(2)O (3) (azpy =4,4'-azopyridine, dipytz = di-3,6-(4-pyridyl)-1,2,4,5-tetrazine) reveal pore structure change upon different activation conditions. In addition, the samples activated under different conditions show distinct adsorption behaviors of N(2) and O(2) gases. Furthermore, hydrogen adsorption properties of activated 1-3 were studied. The results indicated that the activation process could affect the hydrogen enthalpy of adsorption.

Two new porous coordination polymers (PCPs) based on different nanosized C3 symmetry ligands and Zn(II)-benzotriazolate clusters have been synthesized solvothermally. Both of the desolvated complexes show selective uptake of CO2 over CH4 and N2 at ambient temperature.

Sparked by the strategy of pillared-layer MOFs, three formate coordination polymers, {[Ni(2)(HCO(2))(3)(L)(2)](NO(3)).2H(2)O}(infinity) (1), {[Co(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (2), and {[Cu(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (3), have been synthesized by employing the rodlike ligand 4,4'-bis(imidazol-1-yl)biphenyl (L) as the pillar. Structural analysis indicates that the title complexes 1-3 are isostructural compounds, which possess metal-formate 2D layers perpendicularly pillared by the ligand L to afford a 3D open framework. This is an interesting example of a Kagome lattice based on the formate mediator. Moreover, the formate anion of this 2D Kagome layer exhibits various bridging modes: anti-anti, syn-anti, and 3.21 modes. Their magnetic measurements reveals that only complex 1 presents the spin canting phenomenon, while its isostructural Co(II) and Cu(II) complexes are simply paramagnets with antiferromagnetic coupling.

Porous Co3O4 hollow tetrahedra were prepared through the thermolysis of metal-organic frameworks and presented reversible capacities of 1196 and 1052 mAh g(-1) at 50 and 200 mA g(-1) after 60 charge/discharge cycles, respectively. Such excellent performances stem from the well-defined hollow structure of Co3O4 tetrahedra.

In our efforts to investigate the coordination architectures of transition metals and organic ligands with tailored structures, we have prepared two structurally related rigid bulky acridine-based ligands, 9-[3-(2-pyridyl)pyrazol-1-yl]- acridine (L(1)) and 9-(1-imidazolyl)acridine (L2), and synthesized and characterized four of their Ag(I) complexes, {[AgL1](ClO4)}2 (1), {[AgL1](NO3)}2 (2), [AgL2(2)](ClO4) (3), and {[(Ag3L2(3))(NO3)](NO3)2(H2O)}(infinity) (4). The single-crystal X-ray diffraction analysis shows that the structures of 1 and 2 are similar to each other, with the two intramolecular Ag(I) centers of each complex being encircled by two L1 ligands; this forms a unique boxlike cyclic dimer, which is further linked to form one-dimensional (1D) chains of 1 and a two-dimensional (2D) network of 2 by intermolecular face-to-face pi...pi stacking and/or weak C-H...O hydrogen-bonding interactions, respectively. 3 has a mononuclear structure, which is further assembled into a 2D network via intermolecular Ag...O and pi...pi stacking weak interactions. 4 possesses two different 1D motifs that are further interlinked through interlayer face-to-face pi...pi stacking and Ag...O weak interactions, resulting in a 2D network. It is worth noting that one of the interesting structural features of 1, 2, and 4 is the presence of obvious C-H...M hydrogen-bonding interactions between the Ag centers and some acridine ring H atoms identified by X-ray diffraction on the basis of the van der Waals radii. Furthermore, as a representative example, full geometry optimization on the basis of the experimental structure, the natural bond orbital (NBO), and topological analysis of 1 were carried out by DFT and AIM (Atoms in Molecules) calculations. The total C-H...Ag interaction energy in 1 is estimated to be about 14 kJ/mol. Therefore, this work offers three new rare examples (1, 2, and 4) that exhibit C-H...Ag weak interactions, in which the N donors of the acridine rings coordinate to Ag(I) ions. Also, these results strongly support the existence of C-H...Ag close interactions and allow us to have a better understanding of the nature of such interactions in the coordination supramolecular systems.

This report describes the synthesis and X-ray characterization of a series of L(n)AgX complexes wherein Ln = PhS(CH2)nSPh (n = 2, 4, 6, 10) and X = CF3SO3-, CF3COO-, CF3CF2COO-, CF3CF2CF2COO-, NO3-, and ClO4-. This study was undertaken in order to rationalize the structure of the coordination networks formed as a function of the anion coordinating strength and the ligand structure. The following complexes were examined: with L(2), CF3SO3- (1), CF3COO- (2), ClO4- (3); L4, CF3SO3- (4), CF3COO- (5), CF3CF2COO- (6), CF3CF2CF2COO- (7); L6, CF3COO-.H2O (8), CF3CF2COO- (9), CF3CF2CF2COO- (10); and L10, NO3- (11). The anions selected are classified in three groups of increasing coordinating strength: perchlorates, fluorosulfonates, and perfluorocarboxylates. Except in two cases, all complexes form 2D-coordination networks. The 2D-network in 1 (L2, CF3SO3-) is made up of Ag(I) and L2, while the anion is only a terminal co-ligand that completes the trigonal coordination around Ag(I). In 4 (L4, CF3SO3-), a 1D-coordination polymer, [Ag-L4-]infinity, is observed where the anions are coordinated to Ag(I) in a trigonal fashion. The perfluorocarboxylates form tetrameric units in a zigzag shape, but only with the L4 ligand. In these (6 and 7), the silver-silver distances are very short, especially those of the central bond, indicating the presence of weak Ag-Ag interactions. Dimers, with short silver-silver distances, are observed with ligands L2 and L6 and perfluorocarboxylates. In 8 (L6, CF3COO-.H2O), a 3D channel-like structure is built through water molecules that connect adjacent layers. An unusual stoichiometry is noted in 3 (L2, ClO4-, acetone); Ag:L is 4:2.5. In 11 (L10 and NO3-), the nitrate acts as a bidentate ligand and an [Ag-NO3-]infinity chain is formed. Adjacent chains are linked by the L10 ligands into a 2D-coordination network.

Seven new CuII complexes based on a binuclear planar unit [Cu(μ-L1)]2, {[Cu(μ-L1)(NO3)(H2O)]2 (1), [Cu(μ-L1)(HL1)(ClO4)]2 (2), [Cu4(μ-L1)6(NO3)2] (3), [Cu4(μ-L1)6(L1)2] (4), [Cu4(μ-L1)6(μ-L2)]n (5), [Cu4(μ-L1)6(μ-L3)]n (6), {[Cu4(μ-L1)4(μ-L4)2](H2O)3}n (7) (HL1 = 3-(2-pyridyl)pyrazole, L2 = 1,8-naphthalenedicarboxylate, L3 = terephthalate, L4 = 2,6-pyridinedicarboxylate)}, have been synthesized and characterized by elemental analysis, IR, and X-ray diffraction. In 1 and 2, the CuII centers are linked by deprotonated pyrazolyl groups to form dinuclear structures. 3 and 4 have similar gridlike tetranuclear structures in which two additional deprotonated L1 ligands bridge two [Cu(μ-L1)]2 units perpendicularly. 5 and 6 consist of similar one-dimensional (1-D) chains in which gridlike tetranuclear copper(II) units similar to that of 3 are further linked by L2 or L3 ligands, respectively. And, in 7, L4 ligands link [Cu(μ-L1)]2 binuclear units to form a tetranuclear gridlike structure in chelating/bridging mode ...

The formation, crystal structures, and properties of a series of three-dimensional (3-D) Cu(II) coordination polymers, [[Cu(L)2(H2O)2](PF6)2(H2O)(1.25)]n (1), [[CuL(N3)2](H2O)(1.5)]n (2), and [[CuL(H2O)(SO4)](H2O)2]n (3), with an angular bridging ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L) are reported. Complex 1 crystallizes in the tetragonal I4(1)/a space group (a = b = 13.462(2) A, c = 46.47(1) A, Z = 8), complex 2 in the orthorhombic Pna2(1) space group (a = 6.379(2) A, b = 10.060(3) A, c = 27.232(9) A, Z = 4), and complex 3 in the orthorhombic P2(1)2(1)2(1) space group (a = 5.510(2) A, b = 10.576(4) A, c = 28.34(1) A, Z = 4). Different polymeric frameworks are obtained by only varying the counterions. These include the 2-fold interpenetrated diamondoid structure of 1, the acentric alpha-Po network of 2, and the chiral open framework of 3 with (6(3)).(6(9).8) topology. The interesting anion-exchange, porous, and magnetic properties of these coordination supramolecules have been investigated in detail.

A coordination polymer based on an unprecedented Fe(20) core has been constructed by in situ ligand conversion, including trapping of an intermediate.

The reaction of various CuII salts with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L) in CH3CN-H2O medium affords different complexes, the solid structures of which are controlled only by the choice of the counteranions. Reaction of Cu-(ClO4)2.6H2O or Cu(NO3)2.3H2O and L yields the novel bimetallic macrocyclic complex [Cu2L2(H2O)6](ClO4)4(H2O)4 (1) [monoclinic, space group P21/m, a = 8.745(5) A, b = 16.179(10) A, c = 14.930(8) A, beta = 93.253(10) degrees, Z = 2] or [CuL(NO3)2]2(CH3CN)2 (2) [triclinic, space group P1, a = 7.863(3) A, b = 8.679(3) A, c = 13.375(5) A, alpha = 74.121(5) degrees, beta = 78.407(6) degrees, gamma = 86.307(6) degrees, Z = 1]. However, with the replacement of CuII perchlorate or nitrate salts with CuSO4.5H2O or Cu(OAc)2.H2O in the above reaction, two different one-dimensional (1-D) coordination polymers [[Cu2L2(H2O)6(SO4)2](H2O)6]n (3) [triclinic, space group P1, a = 7.078(3) A, b = 11.565(4) A, c = 12.561(5) A, alpha = 109.511(6) degrees, beta = 105.265(6) degrees, gamma = 94.042(6) degrees, Z = 1] or [[Cu2L(mu-OAc)4]]n (4) [monoclinic, space group C2/c, a = 20.007(7) A, b = 7.506(2) A, c = 16.062(5) A, beta = 108.912(5) degrees, Z = 4] were obtained. These results unequivocally indicate that the nature of the counteranions, which play different roles in each complex, is the key factor governing the structural topologies of them. The magnetic properties of these CuII complexes have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the magneto-structural correlation has been analyzed in detail.

The synthesis and crystal structure of the three-dimensional coordination polymer of an angular dipyridyl ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L) and Cu(ClO4)2, exhibiting the first CuII diamondoid network with 2-fold interpenetration, {[Cu(L)2(H2O)2](ClO4)(OH)(H2O)2.5}n (1), together with the Cu(OAc)2 complex of L, [Cu(L)2(OAc)2(H2O)](H2O)2(CH3OH) (2), with an unexpected mononuclear structure, are reported. Crystal data for 1: tetragonal, space group I41/a, a = b = 13.477(3) A, c = 46.167(13) A, Z = 8. Crystal data for 2: triclinic, space group P1, a = 7.847(2) A, b = 13.189(4) A, c = 15.948(5) A, α = 75.225(7)°, β = 79.945(6)°, γ = 77.540(5)°, Z = 2. The magnetic properties and anion effect are also discussed.

The reactions of 3,6-di-2-pyridyl-1,2,4,5-tetrazine (DPTZ) with different Cu(II) salts generate two new ligands, 2,5-bis(2-pyridyl)-1,3,4-oxodiazole (L(1)) and N,N'-bis(alpha-hydroxyl-2-pyridyl)ketazine (H(2)L(2)), from the metal-assisted hydrolysis of DPTZ, and form three new complexes: a mononuclear complex [Cu(L(1))(2)(H(2)O)(2)] .2ClO(4) (1), a linear coordination polymer [Cu(L(1))(NO(3))(2)](8) (2), and a cyclic tetranuclear complex [Cu(4)(L(2))(2)(Im)(2)(NO(3))(4)(H(2)O)(2)] (3) (Im = imidazole). Crystal data for 1: space group P2(1)/n with a = 10.339(3) A, b = 10.974(2) A, c = 13.618(4) A, beta = 103.24(1) degrees, and Z = 2. Crystal data for 2: space group C2/c with a = 13.9299(14) A, b = 9.2275(9) A, c = 12.1865(13) A, beta = 111.248(2) degrees, and Z = 4. Crystal data for 3: space group P2(1)/n with a = 9.3422(14) A, b = 15.987(2) A, c = 13.963(2) A, beta = 108.587(3) degrees, and Z = 2. L(1) acts as a bidentate chelating ligand in 1 and as a bis-bidentate chelating ligand in 2 with the shortest intramolecular Cu...Cu distance of 6.093 A. L(2) is a hexadentate ligand to bridge four Cu(II) ions, forming an interesting neutral cyclic tetranuclear complex 3 with Cu...Cu distances varying from 4.484 to 9.370 A. The mechanism of the metal assisted hydrolysis of DPTZ is discussed in detail. Magnetic susceptibility measurements indicate that 2 shows weak ferromagnetic interaction (J = 2.85 cm(-1)) along the 1-D helical chain, and that 3 displays weak antiferromagnetic interaction (J = -1.19 cm(-1) for the N-N bridge) and ferromagnetic interaction (j = 0.11 cm(-1) for the O-C=N bridge) between the adjacent Cu(II) ions.