A copper based pillared-bilayer metal organic framework : its synthesis, sorption properties and catalytic performance

A new 2D pillared-bilayer flexible open metal organic framework {[Cu(tdc)(bpe)](n)center dot 2n(H2O)center dot n(MeOH)} (compound 1) [H(2)tdc = 2,5 thiophenedicarboxylic acid; bpe = 1,2-bis(4-pyridyl)ethane] has been synthesized through a solvent diffusion technique and structurally characterized. The structure analysis reveals that the tdc ligands formed bilayers with the Cu(II) ions along the b-direction and the layers are further pillared by bpe linkers and resulted in a 2D pillared-bilayer porous framework with a four connected uninodal sq1/Shubnikob tetragonal plane net with the Sch lfli symbol {4(4).6(2)}. The framework is enclosed with large square shaped channels (13.7 x 8.35 A(2)) along the bc-plane and the channels are occupied by guest solvent molecules. The adsorption studies reveal that compound 1 shows selective adsorption for CO2 over CH4 at room temperature and it also shows hysteretic sorption for a few protic solvents (H2O and EtOH) and a Type-1 isotherm for an aprotic solvent (CH3CN). The catalytic performance of compound 1 for Glaser type homo-coupling reactions has also been reported

Hydrothermal synthesis, characterization and gas adsorption study of a Zn(II) based 1D coordination polymer

Anew 1D co-ordination polymer [Zn(C10H2O8)(0.5) (C10S2N2H8)center dot 2H(2)O)](n) (1) has been synthesized by in situ formation of a 4-pyt (4-pyridinethiolate) ligand from 4,4'-pyridyldithiol precursor through reductive cleavage of the disulfide bond under hydrothermal conditions. Compound 1 possesses pendent 4-pyt ligands through a Zn-S bond which restricts the framework to expand dimensionality. The compound shows selective CO2 adsorption over N-2 at low temperatures

Synthesis, characterisation, water adsorption and proton conductivity of three Cd(II) based luminescent metal-organic frameworks

Three hydrogen bonded three-dimensional (3D) metal-organic frameworks (MOFs) namely [Cd(L-tart)-(bpy)(H2O)](n)center dot 9n(H2O) (1), [Cd(D-tart)(bpy)(H2O)](n)center dot 9n(H2O) (2) and [Cd(DL-tart)(bpy)(H2O)](n)center dot 6n(H2O) (3) (tart = tartaric acid, bpy = 4,4-bipyridine) have been synthesized by the solvent diffusion technique at room temperature. Compounds 1 and 2 have been characterized by single crystal X-ray analysis, whereas the powder X-ray diffraction patterns show that the structural integrity of compound 3 is similar to 1 and 2. Structural analysis of 1 and 2 shows H-bonded homochiral 3D MOFs, fabricated by the hydrogen bonding interactions between the nearby 2D pillared-layer frameworks through the metal-bound water, metalbound carboxylate, free carboxylic acid and the hydroxy group of L-/D-tart. The absolute configuration of all the compounds was investigated by solid state circular dichroism (CD) spectroscopy, which signifies that 1 and 2 are enantiomers whereas 3 is racemic. The adsorption studies reveal that compounds 1-3 show a significant amount of uptake for water vapor (similar to 239 mL g(-1) for 1, similar to 240 mL g(-1) in 2, whereas 184 mL g(-1) for 3 at P/P-0 approximate to 1 bar) over other solvents (MeOH, EtOH) and an impedance measurement indicates that these compounds show proton conduction (1.3 x 10(-6) S cm(-1) in 1, 1.3 x 10(-6) S cm(-1) in 2 and 4.5 x 10(-7) S cm(-1) in 3) at a higher temperature (358 K) and at 95% relative humidity. The observed conductivity is explained by the so-called vehicle mechanism (activation energy (E-a) = 0.63-0.77 eV). Since all the compounds contain H3O+ cations in the interlayer space, the hydronium ions might act as vehicles to transport the protons in the interlayer space. The photoluminescence properties of all the compounds are also reported

Tuning CO2 uptake and reversible iodine adsorption in two isoreticular MOFs through ligand functionalization

The synthesis and characterization of two isoreticular metal-organic frameworks (MOFs), {[Cd(bdc)(4-bpmh)]}(n)center dot 2n(H2O) (1) and {[Cd(2-NH(2)bdc)(4-bpmh)]}(n)center dot 2n(H2O) (2) [bdc= benzene dicarboxylic acid; 2-NH(2)bdc= 2-amino benzene dicarboxylic acid; 4-bpmh= N, N-bis-pyridin-4-ylmethylene- hydrazine], are reported. Both compounds possess similar two-fold interpenetrated 3D frameworks bridged by dicarboxylates and a 4-bpmh linker. The 2D Cd-dicarboxylate layers are extended along the a-axis to form distorted square grids which are further pillared by 4-bpmh linkers to result in a 3D pillared-bilayer interpenetrated framework. Gas adsorption studies demonstrate that the amino-functionalized MOF 2 shows high selectivity for CO2 (8.4 wt% 273 K and 7.0 wt% 298 K) over CH4, and the uptake amounts are almost double that of non-functional MOF 1. Iodine (I2) adsorption studies reveal that amino-functionalized MOF 2 exhibits a faster I-2 adsorption rate and controlled delivery of I-2 over the non-functionalized homolog 1

A 2D coordination polymer based on Co-3-SBU showing spin-canting ferromagnetic behaviour

A 2D MOF with the secondary building unit [Co-3(CTC)(6)(Py)(2)(OH)(2)] is synthesized using the sodium salt of a flexible ligand, cis, cis-cyclohexane-1,3,5-tricarboxylate (Na-CTC), and a cobalt trimer ([Co3O(CH3COO)(6)(Py)(3)]center dot ClO4). Structural analysis shows that the complex crystallizes in the monoclinic space group P21/n and forms a 2D framework with channel sizes of 9.0 x 4.2 angstrom(2). Magnetic characterization shows spin-canting ferromagnetic behaviour at low temperatures. Frequency dependency for in-phase (chi(M)') and out-of-phase (chi(M)'') signals at low temperatures is observed from the AC measurements. The gas adsorption behaviour suggests selectivity towards CO2 over N-2, and demonstrates enhancement of CO2 uptake (19-33 cm(3) g(-1)) on lowering the temperature (273-195 K)

A family of three magnetic metal organic frameworks : their synthesis, structural, magnetic and vapour adsorption study

Three flexible metal-organic frameworks (MOFs) based on aldrithiol linker and pyromellitate ligand, namely, [Co(aldrithiol)(pyromellitate)(0.5)(H2O)(2)] n (1), [Ni-2(aldrithiol)(2)(pyromellitate)(H2O)(2)](n)center dot 2n(C2H5OH)center dot 11n(H2O) (2) and [Cu(aldrithiol) 2(pyromellitate)](n)center dot 2n(H2O)(3) have been synthesized through slow diffusion technique and characterized by structural, magnetic and adsorption studies. Single crystal X-ray studies show that compounds 1 and 3 have two-dimensional layered structures, whereas compound 2 adopts a threedimensional framework structure. The observed dimensionality change might be due to the different orientation of pyridine rings in the flexible aldrithiol linker and versatile bridging modes of the pyromellitate ligand. In 1 and 2, the pyromellitate ligand coordinates to the metal centre in a monodentate fashion {(K-1)-(K-1)-(K-1)(K-1)-mu 4} and in 3, it coordinates in {(K-1)-(K-1)-mu 2} fashion. The magnetic properties of 1-3 were investigated in detail and show weak antiferromagnetic coupling among the metal centres. Vapour sorption studies reveal that compounds 1 and 3 show high methanol vapour uptake, whereas compound 2 shows a decent amount of H2O adsorption. The dehydrated frameworks of 1-3 regenerate the as-synthesized framework structures upon exposure to water vapour

Exploration of structural topologies in metal-organic frameworks based on 3-(4-carboxyphenyl)propionic acid : their synthesis, sorption, and luminescent property studies

Four new compounds (two coordination polymers (CPs) and two metal organic frameworks (MOFs)), namely, [Zn(cpp)(H2O)](n) (1), [Cu(cpp)(4-bpmh)](n)center dot nH(2)O center dot nMeOH (2), [Cd-2(cpp)(2)(3-bpmh)(2)](n)4nH(2)O center dot 2nMeOH (3), and [Cd(cpp)(bpy)(H2O)(2)](n)center dot 2nH(2)O (4), have been synthesized through the slow diffusion technique using cpp ligand and different neutral linkers (H(2)cpp = 3-(4-carboxyphenyl)propionic acid, 4-bpmh = N,N-bis-pyridin-4-ylmethylene-hydrazine, 3-bpmh = N,N-bis-pyridin-3-ylmethylene-hydrazine, bpy = 4,4-bipyridine). Single crystal X-ray analysis of compounds 1-4 reveals their structural diversities which might have been generated due to both rigidity (aryl carboxylate) and flexibility (aliphatic carboxylates) of cpp ligands as well their bridging modes and the orientation of nitrogen atoms of the neutral linkers. In addition, the dihedral angle in the aliphatic carboxylates of cpp ligand is also playing an important role in directing the final structural arrangement. Compound 1 exhibits a uninodal 6-connected three-dimensional (3D) coordination polymer with point Schalfli symbol {3(3).5(9).6(3)} and shows an uncommon lcy; 6/3/c1 topological type. Compound 2 reveals a 6-connected uninodal 3D framework with point Schalfli symbol {4(8).6(6).8} and shows a rare rob topology. Compound 3 formed a 4-connected uninodal two-dimensional framework with point Schalfli symbol {4(4).6(2)} and displays a sql/Shubnikov tetragonal plane net topology, whereas 4 forms a one-dimensional CP which subsequently extended to 3D supramolecular networks through hydrogen bonding interactions. Gas adsorption studies reveal that compounds 1 and 2 show selective adsorption of CO2 over other gases (N-2, CH4) at low temperature, whereas 3 and 4 show no uptake. Vapor sorption studies reveal that compounds 1, 2, and 4 show high uptake capacities for H2O over MeOH and EtOH. Solid state luminescence studies of compounds 1, 3, and 4 display significant red shifts compared to free ligands

Third-Generation Breathing Metal–Organic Framework with Selective, Stepwise, Reversible, and Hysteretic Adsorption Properties

A new 2D interdigitated and highly flexible, breathing metal–organic framework has been synthesized through a diffusion technique by using the aldrithiol linker and pyromellitate ligand. The compound shows selective, stepwise, reversible, and hysteretic adsorption properties for CO₂ gas and H₂O, MeOH, and CH₃CN vapors