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Sensors with high-sensitivity for resistive methanol gas detection are highly desirable. Herein, we report newly designed ultrathin anionic metal-organic framework (MOF) nanosheets (NSs), with an average thickness of 10 nm and an electrical conductivity of 3.77 × 10-4 S cm-1. The ultrathin MOF NSs can be used as the active material in an electronic methanol gas sensor, which exhibits high sensitivity toward methanol gas at room temperature, i.e., high Rair/Rgas (363.2 at 100 ppm), fast gas response/recovery speed (6 s/2 s at 20 ppm), long-term stability, and superior crossselectivity against other interfering gases. [ABSTRACT FROM AUTHOR]

To assemble metal-organic supramolecules such as a metallamacrcocycle and metal-organic coordinaifon cage (MCCC), a series of flexible dicarboxylate ligands with the appropriate angle, 2,2'-(2,3,5,6-tetramethyl-1,4-phenytene)-bis(methylene)bis(sulfanediyl)dibenzoic acid (H2L1), 2,2'-(2,5-diniethyl-1,4-phenylene)bis(methylene)bis(sulfanediyl)-dibenzoic acid (H2L2), 2,2'-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl)dinicotinic acid (H2L3), and 2,2'-(2,4,6-trrmethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic add (H2L4), have been designed and synthesized. Using these flexible ligands to assemble with metal ions, six metal-organic supramolecules, Cd2(L1)2(dmf)4-(H2O)2∙H2O (1), Mn3(L2)2(2L2)(dmf)2(H2O)2∙5dmf (2), Cu4(L3)4(H2O)4∙3dmf (3), Cu4(L4)4(dmf)2(EtOH)2∙8dmf∙6H2O (4), Mn4(L4)4(dmf)4(H2O)4∙6dml∙H2O (5), and Mn3(L4)3(dmf)4∙2dmf&3x2219;3H2O (6), possessing a rectangular macrocycle, MOCCs or their extensions, and 1D or 2D coordination polymers, have been isolated. All complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex lisa discrete rectangular macrocycle, while complex 2 is a 20 macrocycle-based coordination polymer in which the L2 ligand adopts both syn and anti conformations. Complexes 3-5 are discrete MOCCs in which two binuclear metal dusters are engaged by tour organic ligands. The different geometries of the secondary building units (SBUS) and the axial coordinated solvates on the SBUS result in their different symmetries. Complex 6 is a 1 D coordination polymer, extended from a MCCC made up of two metal ions and three L4 uganda. All of the flexible dicarboxylate ligands adopt a syn conformation except that in complex 2, indicating that the syn conforniationat ligand is helpful for the formation of a metallamacrocycle and a MOCC. The magnetic properties of complexes 5 and 6 have also been studied. [ABSTRACT FROM AUTHOR]

Two 1D coordination polymers with a 1D zigzag and a helical chain, respectively, have been solvothermally synthesized. The different coordinated small molecules on the cadmium ion have significant influences on the formation of different architectures. Due to the existence of supramolecular interactions between the helices in complex 2, the same chirality is preserved, resulting in a chiral architecture. By introducing a chiral molecule as cosolute, the bulk homochiral crystallization from achiral precursors for 2can be achieved. [ABSTRACT FROM AUTHOR]

Three flexible dicarboxylate ligands 2,2′-(1,2-phenylenebis(methylene))bis(sulfanediyl)dibenzoic acid (H2L6), 2,2′-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(oxy)dibenzoic acid (H2L7) and 2,2′-(1,4-phenylenebis(methylene))bis-(sulfanediyl)dinicotinic acid (H2L8), have been designed and synthesized. All ligands can adopt synor anticonformations and the positions of the functional substituents in the central benzene ring change gradually from 1,2-, 1,3- to 1,4-position. By applying these flexible ligands to assemble with copper ions, four metal–organic complexes based on paddlewheel SBU have been isolated. Complexes 1and 2are discrete molecular chairs. Complex 3is a 1D molecular-chair-based coordination polymer. The molecular chairs, similar to that found in 1and 2, are infinitely connected by the bridging 4,4′-bipy ligands to result in the formation of the 1D chain structure. Complex 4is a two-dimensional wavelike layer structure containing a 68-member ring. Both L6and L7in 1and 2adopt synconformation, while L8adopts anticonformation, which results in the formation of the 2D layer structure of complex 4. [ABSTRACT FROM AUTHOR]

Applying a nonplanar dicarboxylate ligand, a new 3D metal–organic framework, Zn(TBDC1)1/2(TBDC2)1/2(1), possessing a rare (3,5)-connected net has been synthesized and characterized; complex 1can be formed from a 2D double layer by thermally liberating the coordinated water and dmf molecules, simultaneous with luminescence-increased changes. [ABSTRACT FROM AUTHOR]

Three novel metal–organic frameworks, Cu4(OH)2(SO4)(HBTC)2(bpy)·bpy (1), Cu1.5(H2O)(TMBTC)(bpy)·1/2H2O (2) and Cd2(H2O)5(TMBTC)(bpy)2·NO3·3H2O (3), constructed from mixed organic ligands, have been synthesized and characterized. Complex 1 crystallizes in monoclinic space group C2/c and possesses a 3D three-fold interpenetrating framework. The copper ions were first connected by HBTC and SO42− to generate a 1D ladder, which was further linked by a 4,4′-bipyridine ligand to give rise to a 3D interpenetrating framework. Complex 2 crystallizes in monoclinic space group P2/c and possesses a 3D two-fold interpenetrating framework. Similar to 1, the copper ions were first connected by TMBTC to generate a 1D tubular unit, which can be considered as the assembly block. The 1D tubular unit was further linked by 4,4′-bipyridine ligands to result in the formation of the 3D framework. Complex 3 crystallizes in monoclinic space group Cc and has a three-dimensional structure. Different from 1 and 2, the cadmium ions were first connected by a 4,4′-bipyridine ligand to form a 1D chain as the assembly unit, which was further linked by TMBTC ligand to generate the final 3D framework. The photoluminescence measurement of 3 in the solid state at room temperature showed that complex 3 exhibits luminescence, which can be assigned to an intraligand π→π* transition. [ABSTRACT FROM AUTHOR]

The self-assembly of flexible bended dicarboxylate ligand, 2,2′-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)-bis(sulfanediyl)-dibenzoic acid (H2L), with Mn(OAc)2·4H2O resulted in the formation of a novel metal–organic coordination cage with binuclear manganese SBU as the vertex, which represents the first metal–organic coordination cage constructed from a flexible dicarboxylate ligand and a binuclear SBU. [ABSTRACT FROM AUTHOR]

Zinc paddlewheel metal-organic frameworks (MOFs) frequently exhibit low stability or complete collapse upon the removal of axial ligands. Hence, there are very few reports on gas adsorption of zinc paddlewheel MOFs. In this work, the N2 and H2 adsorption measurements were carried out for a zinc MOF (namely, SDU-1) based on two types of paddlewheel secondary building units (SBUs): [Zn2(COO)3] and [Zn2(COO)4]. Because of the existence of inherent surface instability upon removal of solvates in zinc paddlewheel SBU, SDU-1 possesses a very low surface area. Through metal-ion metathesis in a single-crystal-to-single-crystal fashion, the Zn2+ ions in SDU-1 were exchanged by Cu2+ ions to generate Cu-SDU-1. Through the measurements of gas adsorption and catalytic test, the porosity and catalytic capacity of Cu-SDU-1 have been improved significantly, compared to SDU-1. [ABSTRACT FROM AUTHOR]

Biphasic solvothermal reaction of Cu(NO3)2·6H2O and 2,3,5,6-tetramethyl-1,4-benzenedicarboxylic acid (H2TBDC) resulted in the formation of a novel coordination polymer, [Cu(TBDC)1/2]·H2O (BPS-1). BPS-1possesses a 3D framework containing 1D Cu(i)–COO helical chains. The use of an organic solvent with a high boiling point and an extension of the reaction time play important roles in the reduction of Cu(ii) ions to Cu(i) ions and the formation of BPS-1. [ABSTRACT FROM AUTHOR]

The assembly of a fluorescent dicarboxylate ligand with a barium ion resulted in the formation of a 3D metal-organic framework, Ba5(ADDA)5(EtOH)2(H2O)3•5DMF (UPC-17), based on a 1D rod-shaped secondary building unit. The unprecedented solvent-dependent sensitivities of UPC-17 for the detection of Fe3+/Al3+ ions and 4-nitrophenol with high efficiency were observed for the first time. Significantly, UPC-17 exhibits superior "turn-off" detection for the Fe3+ ion in methanol and acetone emulsions but shows "turn-on" detection in tetrahydrofuran emulsion. Furthermore, the visible color changes in the detection process make them easy to distinguish by the naked eye, which further increases its application potential. [ABSTRACT FROM AUTHOR]

A three-dimensional porous Zn metal-organic framework (UPC-12) with high thermal and chemical stability was isolated in high yield and purity from a hydrothermal reaction. UPC-12 exhibits high selectivity for CO2 due to the formation of hydrogen bonds between CO2 molecules and the −COOH groups exposed inside the channels and the effective π-π interactions between CO2 molecules and the pillared bipyridine moieties of the MOF. The adsorption-desorption process was studied, for the first time, by both 13C CP-TOSS NMR spectroscopy and in situ DRIFTS. [ABSTRACT FROM AUTHOR]

Four metal-organic complexes [Ni(HET)(phen)(H2O)]·(HET)·H2O (1), [Cu(HET)(phen)(H2O)]·1.5H2O (2), [Cu2(HET)2(bipy)1.5(H2O)]·15DMF·2H2O (3), and [Cd2O(HET)2(bipy)(H2O)]·2H2O·EtOH (4) (HET = 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine) have been synthesized via hydro- or solvothermal reactions. It was found that complexes 1 and 2 are two-dimensional (2D) structures built from discrete complexes via the typical intermolecular interactions, and there was a closed loop built from the lattice water and carboxylate groups in 1 through intramolecular hydrogen bonds. Complex 3 exhibits three-dimensional (3D) structure with 5-connected bnn hexagonal BN topology. Complex 4 features a non-interpenetrating sql 2D coordination network, which is further linked into a 3D structure by C-H···Cl weak interaction. The properties of magnetism, fluorescence, and electrochemistry have also been investigated in this paper. [ABSTRACT FROM AUTHOR]

Two 2-fold interpenetrating metal-organic frameworks based on 1,3,5-tris[2-(4-carboxyphenyl)-1-ethynyl]-2,4,6-trimethylbenzene(H3LMe), [Mn3(LMe)2(DMF)4(H2O)]∙1.5DMF∙3.5H2O (1) and [Cd3(LMe)2(DMF)][Cd3(LMe)2(DMF)2(H2O)]∙5DMF∙3.5H2O (2), have been synthesized by using rigid trigonal H3LMe and nitrate under solvothermal conditions. Complex 1 displays a three-dimensional open framework with rare (3,6)-connected 2-nodal sit topology, whereas complex 2 features a new (3,3,6)-connected topology. Both 1 and 2 are blue fluorescent, and the magnetic measurement of 1 indicates that metal centers within the trinuclear cluster exhibit antiferromagnetic coupling interactions. Significantly, although complexes 1 and 2 have similar total solvent-accessible volumes, 2 demonstrates a higher Brunauer-Emmett-Teller surface area than that of 1, further indicating the influence of pore structure on gas absorption. [ABSTRACT FROM AUTHOR]

Two 3D noninterpenetrating porous metal-organic frameworks (PMOFs) [Cd3(L¹)2(DMA)2]·DMA [1, H3L#185; = tris(p-carboxylic acid)tridurylborane] and [Zn3(L2)3(H2O)2]·5H2O·2EtOH [2, H2L² = 4,4'-((2,3,5,6-tetramethylphenyl)boranediyl)bis(2,3,5,6-tetramethylbenzoic acid)] were synthesized by employment of a C3-symmetric ligand (H3L¹) to assembly with Cd(NO3)2 or Zn(NO3)2. Complex 1 exhibits a (3, 6)-connected topological network based on a Cd3 cluster and Y-shaped trinodal organic linker. Complex 2 shows a 6-connected topology, since in situ decarboxylic reaction of the initial H3L1 occurred to generate a new ligand, H2L², which can be considered as a linear linker. Both 1 and 2 exhibit blue fluorescence. Significantly, complex 1 with larger channels is unstable upon the removal of guest molecules. In contrast, activated 2 exhibits higher stability and permanent porosity. [ABSTRACT FROM AUTHOR]

The self-assembly of the flexibly bonded dicarboxylate ligand, 2,2′-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)bis(sulfanediyl) dibenzoic acid (H2L1), with La(NO3)3·6H2O resulted in the formation of three layered coordination polymers. Interestingly, three complexes are supramolecular isomers and their structures are highly influenced by the concentration of the starting reagents and the reaction vessel, such as a glass tube or a Teflon-lined steel bomb. [ABSTRACT FROM AUTHOR]

A pair of framework-catenation isomers (UPC-19 and UPC-20) based on an anthracene-functionality dicarboxylate ligand were synthesized and characterized for the first time through tuning of the dimensionality of interpenetration. The interpenetration dimensionality significantly influences the properties including the porosity, gas-uptake capacity, and fluorescent sensing ability: UPC-19 with 5-fold interpenetration is nonporous, whereas the 3-fold interpenetration form of UPC-20 is porous and exhibits selective adsorption of CO2 and fluorescent sensing of Cu2+ and Fe3+ through fluorescence quenching. [ABSTRACT FROM AUTHOR]

A new porous zirconium metal--organic frame work (Zr MOF), Zr6 (μ3 - 0)4(/irOH)4(OH)6(H2O)6(BTB)2.6DMFH6O (1; H3BTB = 5'- (4-carboxyphenyl) [1,1' :3' 1"-terphenyl] -4,4"-dicarboxylic acid), based on Zr6 clusters and tricarboxylate ligands has been constructed and characterized. The Zr6 dusters were linked by BTB ligands to generate a 2D network of kgd topology. The interpénétrations among the 2D networks gave rise to a 3D porous framework, which represents the first Zr MOF constructed from 2D → 3D interpénétration. The gas uptake and catalytic properties for 1 have also been studied. [ABSTRACT FROM AUTHOR]

By application of a newly developed C3-symmetric tripodal carboxylate ligand, 1,1',1″-(benzene-1,3,5-triyl)tripiperidine-4-carboxylic acid (H3BTPCA) to assemble with zinc ion in the presence of pyridine, a novel 2-fold interpenetrating polyhedral metal—organic framework with a primitive cubic network based on supermolecular building blocks (SBBs) has been synthesized. The basic paddlewheel secondary building units (SBUs) are connected by deprotonated BTPCA ligands to generate an octahedron as the SBB, which is further connected through the six vertexes by sharing the paddlewheel SBUs to give rise to the 3D primitive cubic network. [ABSTRACT FROM AUTHOR]