scholarly journals Morphology and adsorption of chromium ion on uranium 1,2,4,5-benzenetetracarboxylic acid metal organic framework (MOF)

2016 ◽  
Vol 70 (5) ◽  
pp. 565-572 ◽  
Author(s):  
Remy Vala ◽  
Donbebe Wankasi ◽  
Ezekiel Dikio
Keyword(s):  
Electron Microscopy ◽  
Porous Structure ◽  
Metal Organic Framework ◽  
Tetracarboxylic Acid ◽  
X Ray Diffraction ◽  
Kinetic Determination ◽  
Transmission Electron ◽  
Metal Organic ◽  
Organic Framework

In this paper, we report the synthesis of metal organic framework of uranium 1,2,4,5-benzene tetracarboxylic acid (U-H4btec MOF) by solvothermal method. The obtained MOF was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), Energy dispersive spectroscopy (EDS), thermogravimetric and differential thermogravimetric analysis (TGA/DTA). The morphology of the uranium 1,2,4,5-benzene tetracarboxylic acid MOF observed by SEM, revealed the presence of flaky porous structure. Adsorption of Cr3+ from aqueous solution onto the uranium 1,2,4,5-benzene tetracarboxylic acid MOF was systematically studied. Langmuir and Freundlich adsorption isotherms were applied to determine the adsorption capacity of the MOF to form a monolayer. Kinetic determination of the adsorption of Cr3+ suggested both chemisorption and physisorption probably due to the presence of carbonyl groups within the MOF and its porous structure.

scholarly journals Twinning in Zr-Based Metal-Organic Framework Crystals

Chemistry ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 777-786
Author(s):  
Sigurd Øien-Ødegaard ◽  
Karl Lillerud
Keyword(s):  
Crystal Structures ◽  
Metal Organic Framework ◽  
Special Importance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Organic ◽  
Ab Initio Structure ◽  
Crystal Twinning ◽  
Organic Framework

Ab initio structure determination of new metal-organic framework (MOF) compounds is generally done by single crystal X-ray diffraction, but this technique can yield incorrect crystal structures if crystal twinning is overlooked. Herein, the crystal structures of three Zirconium-based MOFs, that are especially prone to twinning, have been determined from twinned crystals. These twin laws (and others) could potentially occur in many MOFs or related network structures, and the methods and tools described herein to detect and treat twinning could be useful to resolve the structures of affected crystals. Our results highlight the prevalence (and sometimes inevitability) of twinning in certain Zr-MOFs. Of special importance are the works of Howard Flack which, in addition to fundamental advances in crystallography, provide accessible tools for inexperienced crystallographers to take twinning into account in structure elucidation.

Metal-Organic Framework Fe3O(BPDC)3 as an efficient catalyst for the oxidative couling reaction of benzaldehyde and (E)-1-phenylethan-1-one O-acetyl oxime

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Son Doan Hoai ◽  
Tram Van Thi ◽  
Giao Dang Huynh ◽  
Nhan Le Thi Hong ◽  
Nam Phan Thanh Son
Keyword(s):  
Electron Microscopy ◽  
Oxidative Coupling ◽  
Metal Organic Framework ◽  
Coupling Reaction ◽  
Reaction Yield ◽  
Efficient Catalyst ◽  
Oxidative Coupling Reaction ◽  
Transmission Electron ◽  
Metal Organic ◽  
Organic Framework

A porous crytalline metal-organic framework Fe3O(BPDC)3 was synthesized, and its properties were characterized by various techniques, including X-ray powder diffraction (PXRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen physisorption measurements. The Fe3O(BPDC)3 was used as an efficient catalyst for the oxidative coupling reaction of benzaldehyde and (E)-1-phenylethan-1-one O-acetyl oxime to form 2,4,6-triphenylpyridine as desired product. The reaction could proceed readily, with more than 83 % reaction yield being achieved after 360 min at 140 oC in the presence of 10 mol% Fe3O(BPDC)3) catalyst and Di-tert-butyl peroxide as an oxidant. This Fe-MOF exhibited higher activity than other MOFs and traditional homogeneous catalysts in the oxidative coupling reaction. The transformation could only proceed to obtain main product in the presence of Fe3O(BPDC)3.

Enhanced Microwave Absorption Properties of Metal Organic Framework (MOF)-Derived Carbonaceous ZnO Incorporated Reduced Graphene Oxide Composites

NANO ◽  
2019 ◽  
Vol 14 (01) ◽  
pp. 1950005 ◽  
Author(s):  
Zhongfei Liu ◽  
Jiangtao Yuan ◽  
Hui Zhang ◽  
Kuangwei Xiong ◽  
Shaowei Jin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Metal Organic Framework ◽  
X Ray Diffraction ◽  
Microwave Absorption Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Metal Organic ◽  
Oxide Composites

In this paper, the MOFs-derived carbonaceous ZnO and RGO (carbonaceous ZnO/RGO) composites have been prepared by the wet chemical method and carbonization process. The as-prepared products are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), Raman spectra, thermogravimetric (TG) analysis and X-ray photoelectron spectroscopy (XPS). The electromagnetic parameters of carbonaceous ZnO/RGO composites are investigated by the vector network analyzer. The results exhibit carbonaceous ZnO/RGO composites have a maximum absorption of [Formula: see text][Formula: see text]dB at 6[Formula: see text]GHz with thickness of 3.5[Formula: see text]mm and the effective absorption (below [Formula: see text][Formula: see text]dB) bandwidth is up to 1.92[Formula: see text]GHz (from 5.28 to 7.2[Formula: see text]GHz). Thus, the carbonaceous ZnO/RGO composites have great potential in the field of electromagnetic wave absorption.

scholarly journals The impact of crystal size and temperature on the adsorption-induced flexibility of the Zr-based metal-organic framework DUT-98

2019 ◽  
Author(s):  
Simon Krause ◽  
Volodymyr Bon ◽  
Hongchu Du ◽  
Rafal E Dunin-Borkowski ◽  
Ulrich Stoeck ◽  
...  
Keyword(s):  
Crystal Size ◽  
Metal Organic Framework ◽  
Type I ◽  
Adsorption Behaviour ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Adsorption Of Nitrogen ◽  
Metal Organic ◽  
The Impact ◽  
Organic Framework

In this contribution we analyse the influence of adsorption cycling, crystal size, and temperature on the switching behaviour of the flexible Zr-based metal-organic framework DUT-98. We observe a shift in the gate opening pressure upon cycling of adsorption experiments of micro meter-sized crystals and assign this to a fragmentation of the crystals. In a series of modulated syntheses we downsize the average crystal size of DUT-98 crystals from 120 µm to 50 nm and characterize the obtained solids by X-ray diffraction, infrared spectroscopy, as well as scanning and transmission electron microscopy. We analyse the adsorption behaviour by nitrogen and water adsorption at 77 K and 298 K, respectively and show that adsorption-induced flexibility is only observed for micro meter-sized crystals. Nanometer-sized crystals were found to exhibit reversible type I adsorption behaviour upon adsorption of nitrogen and exhibit a crystal-size dependent steep water uptake of up to 20 mmol g-1 at 0.5 p/p 0 with potential for water harvesting and heat pump applications. We furthermore investigate the temperature-induced structural transition by in situ PXRD. At temperatures beyond 110 °C the open pore state of nano meter-sized DUT-98 crystals are found to irreversibly transform in a closed pore state. The connection of crystal fragmentation upon adsorption cycling and the crystal size-dependence of the adsorption-induced flexibility is an important finding for evaluation of these materials in future adsorption-based applications. This work thus extends the limited amount of studies on crystal size effects in flexible MOFs and hopefully motivates further investigations into this field.

scholarly journals Determination of the dehydration pathway in a flexible metal–organic framework by dynamic in situ x-ray diffraction

2020 ◽  
Vol 7 (3) ◽  
pp. 034305
Author(s):  
Ian M. Walton ◽  
Jordan M. Cox ◽  
Shea D. Myers ◽  
Cassidy A. Benson ◽  
Travis B. Mitchell ◽  
...  
Keyword(s):  
Metal Organic Framework ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Organic ◽  
Flexible Metal ◽  
Organic Framework

Synthesis and Structure of a Clathrated Two-Dimensional Metal-Organic Framework: [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2·H2O (L = Bis(1-pyrazinylethylidene)hydrazine)

2008 ◽  
Vol 73 (1) ◽  
pp. 24-31
Author(s):  
Dayu Wu ◽  
Genhua Wu ◽  
Wei Huang ◽  
Zhuqing Wang
Keyword(s):  
Metal Organic Framework ◽  
Channel Structure ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Square Planar ◽  
Metal Organic ◽  
Aqueous Meoh ◽  
Organic Framework

The compound [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2 was obtained by the reaction of Cd(ClO4)2, bis(1-pyrazinylethylidene)hydrazine (L) and 4,4'-bipyridine in aqueous MeOH. Single-crystal X-ray diffraction has revealed its two-dimensional metal-organic framework. The 2-D layers superpose on each other, giving a channel structure. The square planar grids consist of two pairs of shared edges with Cd(II) ion and a 4,4'-bipyridine molecule each vertex and side, respectively. The square cavity has a dimension of 11.817 × 11.781 Å. Two guest molecules of bis(1-pyrazinylethylidene)hydrazine are clathrated in every hydrophobic host cavity, being further stabilized by π-π stacking and hydrogen bonding. The results suggest that the hydrazine molecules present in the network serve as structure-directing templates in the formation of crystal structures.

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