Tamas Panda

Solution mediated phase transformation (RHO to SOD) in porous Co-imidazolate based zeolitic frameworks with high water stability.

Here we report a highly porous, water stable Co based ZIF [CoNIm (RHO)] and its solution mediated phase transformation to a less porous and water unstable ZIF [CoNIm (SOD)]. CoNIm (RHO) has high Langmuir surface area [2087 m(2) g(-1)] as well as high water adsorption [200 cm(3) (STP) g(-1)] capacity.

Fine-tuning the balance between crystallization and gelation and enhancement of CO2 uptake on functionalized calcium based MOFs and metallogels

The synthesis, structure, gas adsorption and catalytic properties of a new 3D porous, crystalline metal–organic framework (Ca-5TIA-MOF) as well as stable viscoelastic metallogels (Ca-5TIA-Gel) are reported. Remarkably, the preparation of both types of materials can be carried out starting from the same organic ligand (i.e. 5-(1,2,4-triazoleyl)isophthalic acid (5TIA)), divalent metal ion (i.e. Ca(II)) and organic solvent (i.e. DMF). In this particular case, the presence of water in the solvent system favors the formation of a crystalline MOF, whereas a pure organic solvent induces gelation. The characterization of the materials was carried out using a series of techniques including XRD, FT-IR, TGA, TEM, SEM, SAXS and dynamic rheology. Experimental PXRD peaks of both Ca-5TIA-xerogel and Ca-5TIA-MOF matched reasonably well with simulated PXRD, suggesting the presence of, at least, some common structural elements in the 3D networks of both xerogel and crystalline phases. Moreover, the nature of the metal counteranion was found to have a critical influence on the gelation phenomenon. To the best of our knowledge, this report describes unprecedented Ca-based LMW-metallogels, as well as the first porous Ca-based MOF, which shows adsorption capacity for CO2 at 1 atm pressure. Interestingly, Ca-5TIA-xerogel presented 20% higher CO2-uptake than the crystalline Ca-5TIA-MOF at 1 atm and 298 K. Both Ca-5TIA-MOF and Ca-5TIA-Gel also displayed a modest catalytic activity towards the hydrosilylation of benzaldehyde, with slightly better performance for the gel phase material.

Synthesis and structural comparisons of five new fluorinated metal organic frameworks (F-MOFs)

A series of fluorinated metal–organic frameworks (F-MOFs) have been successfully synthesized under hydrothermal condition using 4,4′-(hexafluoroisopropylidene) bis(benzoic acid) (C17H10F6O4, H2hfbba) as a flexible dicarboxylate building block, Cu+2 and various heterocyclic co-ligands. These F-MOFs formulated as [Cu(hfbba)(phen)2]·2(H2hfbba)(H2O)(HCO2) (F-MOF-1), [Cu(hfbba)2(2,2′-bipy)2(H2O)] (F-MOF-2), [Cu(hfbba)(4,4′dime-2,2′-bipy)(HCO2)]·(hfbba)(H2O) (F-MOF-3), [Cu2(hfbba)2(3-mepy)2]·(DMF)2(3-mepy) (F-MOF-4), and [Cu(hfbba)2(phen)2]·0.5(DMF) (F-MOF-5) (hfbba = 4,4′-(Hexafluoroisopropylidene) bis(benzoate), phen = 1,10-phenanthroline; 2,2′-bipy = 2,2′-bipyridine; 4,4′dime-2,2′-bipy = 4,4′dimethyl 2,2′-bipyridine; 3-mepy = 3-methyl-pyridine and DMF = dimethyl formamide) display interesting H-bonded, 1D and 2D structural features. All these F-MOFs were structurally determined by single-crystal X-ray diffraction. F-MOF-1 and 5 form a distorted octahedral Cu+2 secondary building unit (SBU). F-MOF-5 forms a one-dimensional architecture constructed from Cu2+ ions bridged by phen anions and two types of 4 hfbba ligands while in F-MOF-1, two among the three acid co-ligands are not coordinated with Cu2+ ions. F-MOF-2 displays dinuclear SBUs within the three-dimensional frameworks whereas F-MOF-3 displays mononuclear SBUs and forms a one-dimensional chain. F-MOF-4 display a interesting 2D framework with conventional Cu2(CO2)4 paddle wheel SBU. In the crystal structures four hfbba ligands, each coordinated to a dicopper paddlewheel unit via one of their carboxylate groups. Solid-state properties such as UV-vis and thermal stability of F-MOF-1–5 have also been studied.

Structural diversity in a series of metal-organic frameworks (MOFs) composed of divalent transition metals, 4,4'-bipyridine and a flexible carboxylic acid

A series of flexible metal–organic frameworks (MOFs) have been successfully synthesized under hydrothermal condition using 1,3-adamantanediacetic acid (C14H20O4, H2ADA) as a flexible dicarboxylate building block, 4,4′-bipyridine and transition metal ions [Cd(II), Zn(II), and Mn(II)] as metal centers in DMF and aqueous media. These MOFs formulated as [Cd(ADA)(4,4′-bipy)0.5]·(DMF) (Cd-ADA-1), [Mn(ADA)(4,4′-bipy)0.5]·(DMF) (Mn-ADA-1), Zn(ADA)(4,4′-bipy)0.5 (Zn-ADA-1), and [Mn(HADA)2(4,4′-bipy)(H2O)2] (Mn-ADA-2) (ADA = 1,3-adamantanediacetate, 4,4′-bipy = 4,4′-bipyridine and DMF = N,N′-dimethyl formamide) display interesting 1D, 2D and 3D structural features depending on the solvent of synthesis. All these MOFs were structurally determined by single-crystal X-ray diffraction. The coordination modes of this ligand are discussed and in addition, thermal stability and hydrogen (H2) and carbon-dioxide (CO2) adsorption properties of Cd-ADA-1, Mn-ADA-1 and Zn-ADA-1 are also presented. Hydrogen sorption at 77 K and up to 1 atm is found to be 0.42, 0.72 and 1.36 wt% without saturation for Zn-ADA-1, Mn-ADA-1 and Cd-ADA-1 samples.

Enhancement of CO2 uptake in iso-reticular Co based zeolitic imidazolate frameworks via metal replacement

Three Co based Zeolitic Imidazolate Frameworks (Co-ZIF-68, -69 and -81) which adopt a GME topology with high porosity have been synthesized. These Co-ZIFs show high CO2 (273 K/298 K) uptake compared to their isostructural Zn based analogues, which has been proved experimentally as well as by ab initio calculations.