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Faraday Discussions

A R Kaija, C E Wilmer
Designing better porous materials for gas storage or separations applications frequently leverages known structure-property relationships. Reliable structure-property relationships, however, only reveal themselves when adsorption data on many porous materials are aggregated and compared. Gathering enough data experimentally is prohibitively time consuming, and even approaches based on large-scale computer simulations face challenges. Brute force computational screening approaches that do not efficiently sample the space of porous materials may be ineffective when the number of possible materials is too large...
June 21, 2017: Faraday Discussions
Sai Puneet Desai, Camille D Malonzo, Thomas Webber, Jiaxin Duan, Anthony B Thompson, Stephen J Tereniak, Matthew R DeStefano, Cassandra T Buru, Zhanyong Li, R Lee Penn, Omar K Farha, Joseph T Hupp, Andreas Stein, Connie C Lu
NU-1000, a mesoporous metal-organic framework (MOF) featuring hexazirconium oxide nodes and 3 nm wide channels, was infiltrated with a reactive dicobalt complex to install dicobalt active sites onto the MOF nodes. The anchoring of the dicobalt complex onto NU-1000 occurred with a nearly ideal stoichiometry of one bimetallic complex per node and with the cobalt evenly distributed throughout the MOF particle. To access thermally robust multimetallic sites on an all-inorganic support, the modified NU-1000 materials containing either the dicobalt complex, or an analogous cobalt-aluminum species, were nanocast with silica...
June 20, 2017: Faraday Discussions
Qi Sun, Meng Chen, Briana Aguila, Nicholas Nguyen, Shengqian Ma
In this work, the influence of the hydrophilic/hydrophobic nature of metal-organic framework (MOF) materials on the catalytic performance of supported Pd nanoparticles for biofuel upgrade was studied. We show that the introduction of hydrophilic groups on a MOF can greatly enhance the performance of the resultant catalyst. Specifically, Pd nanoparticles supported on MIL-101-SO3Na with superhydrophilicity (Pd/MIL-101-SO3Na) far outperforms pristine MIL-101 and the benchmark catalyst Pd/C in the hydrodeoxygenation reaction of vanillin, a model component of pyrolysis oil derived from the lignin fraction...
June 19, 2017: Faraday Discussions
Nathan C Thacker, Pengfei Ji, Zekai Lin, Ania Urban, Wenbin Lin
We report here the synthesis of a robust and highly porous Fe-phenanthroline-based metal-organic framework (MOF) and its application in catalyzing challenging inter- and intramolecular C-H amination reactions. For the intermolecular amination reactions, a FeBr2-metalated MOF selectively functionalized secondary benzylic and allylic C-H bonds. The intramolecular amination reactions utilizing organic azides as the nitrene source required the reduction of the FeBr2-metalated MOF with NaBHEt3 to generate the active catalyst...
June 19, 2017: Faraday Discussions
L Braglia, E Borfecchia, K A Lomachenko, A L Bugaev, A A Guda, A V Soldatov, B T L Bleken, S Øien-Ødegaard, U Olsbye, K P Lillerud, S Bordiga, G Agostini, M Manzoli, C Lamberti
The exceptional thermal and chemical stability of the UiO-66, -67 and -68 classes of isostructural MOFs [J. Am. Chem. Soc., 2008, 130, 13850] makes them ideal materials for functionalization purposes aimed at introducing active centres for potential application in heterogeneous catalysis. We previously demonstrated that a small fraction (up to 10%) of the linkers in the UiO-67 MOF can be replaced by bipyridine-dicarboxylate (bpydc) moieties exhibiting metal-chelating ability and enabling the grafting of Pt(ii) and Pt(iv) ions in the MOF framework [Chem...
June 16, 2017: Faraday Discussions
Keith T Butler, Christopher H Hendon, Aron Walsh
Increasing numbers of electrically active porous framework materials are being reported, with conductivities that make them attractive for technological applications. As design strategies for efficient carrier transport emerge, the next challenge is to incorporate the materials into a functioning device. In thin-film devices interface effects are of critical importance to overall function. In this article we present a method to identify compatible materials combinations to achieve mechanically robust, electronically optimal pairings...
June 16, 2017: Faraday Discussions
Chong Liu, Nathaniel L Rosi
Gradient MOFs contain directional gradients of either structure or functionality. We have successfully prepared two ternary gradient MOFs based on bMOF-100 analogues, namely bMOF-100/102/106 and bMOF-110/100/102, via cascade ligand exchange reactions. The cubic unit cell parameter discrepancy within an individual ternary gradient MOF crystal is as large as ∼1 nm, demonstrating the impressive compatibility and flexibility of the component MOF materials. Because of the presence of a continuum of unit cells, the pore diameters within individual crystals also change in a gradient fashion from ∼2...
June 16, 2017: Faraday Discussions
Frederik Haase, Tanmay Banerjee, Gökcen Savasci, Christian Ochsenfeld, Bettina V Lotsch
Organic solids such as covalent organic frameworks (COFs), porous polymers and carbon nitrides have garnered attention as a new generation of photocatalysts that offer tunability of their optoelectronic properties both at the molecular level and at the nanoscale. Owing to their inherent porosity and well-ordered nanoscale architectures, COFs are an especially attractive platform for the rational design of new photocatalysts for light-induced hydrogen evolution. In this report, our previous design strategy of altering the nitrogen content in an azine-linked COF platform to tune photocatalytic hydrogen evolution is extended to a pyridine-based photocatalytically active framework, where nitrogen substitution in the peripheral aryl rings reverses the polarity compared to the previously studied materials...
June 14, 2017: Faraday Discussions
Dong Yang, Mohammad R Momeni, Hakan Demir, Dale R Pahls, Martino Rimoldi, Timothy C Wang, Omar K Farha, Joseph T Hupp, Christopher J Cramer, Bruce C Gates, Laura Gagliardi
The metal-organic framework NU-1000, with Zr6-oxo, hydroxo, and aqua nodes, was modified by incorporation of hydroxylated Al(iii) ions by ALD-like chemistry with [Al(CH3)2(iso-propoxide)]2 followed by steam (ALD = atomic layer deposition). Al ions were installed to the extent of approximately 7 per node. Single-site iridium diethylene complexes were anchored to the nodes of the modified and unmodified MOFs by reaction with Ir(C2H4)2(acac) (acac = acetylacetonate) and converted to Ir(CO)2 complexes by treatment with CO...
June 14, 2017: Faraday Discussions
Miguel I Gonzalez, Julia Oktawiec, Jeffrey R Long
The metal-organic frameworks Zr6O4(OH)4(bpydc)6 (1; bpydc(2-) = 2,2'-bipyridine-5,5'-dicarboxylate) and Zr6O4(OH)4(bpydc)0.84(bpdc)5.16 (2; bpdc(2-) = biphenyl-4,4'-dicarboxylate) were readily metalated with Ni(DME)Br2 (DME = dimethoxyethane) to produce the corresponding metalated frameworks 1(NiBr2)6 and 2(NiBr2)0.84. Both nickel(ii)-containing frameworks catalyze the oligomerization of ethylene in the presence of Et2AlCl. In these systems, the pore environment around the active nickel sites significantly influences their selectivity for formation of oligomers over polymer...
June 14, 2017: Faraday Discussions
S Hindocha, S Poulston
The metal-organic frameworks (MOFs) MIL-100(Fe), Cu-BTC and CPO-27(Ni) were synthesised in 1 kg batches. The materials were then formed in two different industrially relevant ways. Firstly, dry granulation was used to produce pellets which were sieved to give material with a 300-1000 μm size, and the fines were subsequently recycled to mimic a large scale industrial process. Secondly, wet granulation with a polymer was used to produce granules which were again sieved to 300-1000 μm. XRD data shows that the structures of MIL-100(Fe) and CPO-27(Ni) remain intact during both forming processes, whilst Cu-BTC is shown to degrade during processing...
June 14, 2017: Faraday Discussions
J Haddad, G F S Whitehead, A P Katsoulidis, M J Rosseinsky
Two new amide functionalised metal-organic frameworks, In(OH)CSA and In(OH)PDG, were synthesized using two flexible linkers, N-(4-carboxyphenyl)succinamic acid (CSA) and N,N'-(1,4-phenylenedicarbonyl)diglycine (PDG), respectively. Both structures consist of corner-sharing {InO4(OH)2} octahedra in the form of trans indium hydroxide chains, which are interconnected by the dicarboxylate linkers to form stacked 2-dimensional layers. The different symmetries and configurations of the flexible and rigid features on the linkers results in different supramolecular interactions dominating between linkers, resulting in different shaped pores and functional group orientation...
June 14, 2017: Faraday Discussions
Katie R Smith, Peter M Edwards, Mathew J Evans, James D Lee, Marvin D Shaw, Freya Squires, Shona Wilde, Alastair C Lewis
Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported...
June 13, 2017: Faraday Discussions
D Denysenko, D Volkmer
The cubic metal-organic framework MFU-4l ([Zn5Cl4(BTDD)3], H2-BTDD = bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin) featuring large pore apertures can be modified post-synthetically via partial or complete substitution of peripheral metal sites and chloride side-ligands, thus opening a route towards a large variety of functionalized MOFs. In this way, Ni-MFU-4l-nitrite (or Ni-MFU-4l-NO2) with an analytically determined chemical composition [Zn2.6Ni2.4(NO2)2.9Cl1.1(BTDD)3], containing accessible Ni-NO2 units, was prepared...
June 13, 2017: Faraday Discussions
Nian Zhao, Ping Li, Xin Mu, Chuanfang Liu, Fuxing Sun, Guangshan Zhu
A novel ultra-stable metal-organic framework, MCIF-1, [Cu2(DCI)2](MeCN), based on dicyanoimidazole and Cu(i), has been synthesized at room temperature successfully. MCIF-1 shows excellent water stability and can retain crystallinity after soaking in water for about one week. In addition, MCIF-1 also shows exceptional resistance under both acidic and basic conditions within a large pH range from 0 to 13.5. What is more, after modifying the synthesis procedure slightly, we can produce this material in a large scale during a very short time...
June 13, 2017: Faraday Discussions
Karen Leus, Jeffrey Paulo H Perez, Karel Folens, Maria Meledina, Gustaaf Van Tendeloo, Gijs Du Laing, Pascal Van Der Voort
The dithiol functionalized UiO-66-(SH)2 is developed as an efficient adsorbent for the removal of mercury in aqueous media. Important parameters for the application of MOFs in real-life circumstances include: stability and recyclability of the adsorbents, selectivity for the targeted Hg species in the presence of much higher concentrations of interfering species, and ability to purify wastewater below international environmental limits within a short time. We show that UiO-66-(SH)2 meets all these criteria.
June 13, 2017: Faraday Discussions
Rebecca L Caravan, M Anwar H Khan, Brandon Rotavera, Ewa Papajak, Ivan O Antonov, Ming-Wei Chen, Kendrew Au, Wen Chao, David L Osborn, Jim Jr-Min Lin, Carl J Percival, Dudley E Shallcross, Craig A Taatjes
The reactions of Criegee intermediates with NO2 have been proposed as a potentially significant source of the important nighttime oxidant NO3, particularly in urban environments where concentrations of ozone, alkenes and NOx are high. However, previous efforts to characterize the yield of NO3 from these reactions have been inconclusive, with many studies failing to detect NO3. In the present work, the reactions of formaldehyde oxide (CH2OO) and acetaldehyde oxide (CH3CHOO) with NO2 are revisited to further explore the product formation over a pressure range of 4-40 Torr...
June 12, 2017: Faraday Discussions
Forrest G Lacey, Eloise A Marais, Daven K Henze, Colin J Lee, Aaron van Donkelaar, Randall V Martin, Michael P Hannigan, Christine Wiedinmyer
The African continent is undergoing immense social and economic change, particularly regarding population growth and urbanization, where the urban population in Africa is anticipated to increase by a factor of 3 over the next 40 years. To understand the potential health impacts from this demographical shift and design efficient emission mitigation strategies, we used improved Africa-specific emissions that account for inefficient combustion sources for a number of sectors such as transportation, household energy generation, waste burning, and home heating and cooking...
June 9, 2017: Faraday Discussions
Martin Brüggemann, Nathalie Hayeck, Chloé Bonnineau, Stéphane Pesce, Peter A Alpert, Sébastien Perrier, Christoph Zuth, Thorsten Hoffmann, Jianmin Chen, Christian George
Films of biogenic compounds exposed to the atmosphere are ubiquitously found on the surfaces of cloud droplets, aerosol particles, buildings, plants, soils and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to in bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions...
June 9, 2017: Faraday Discussions
C E Scott, S A Monks, D V Spracklen, S R Arnold, P M Forster, A Rap, K S Carslaw, M P Chipperfield, C L S Reddington, C Wilson
More than one quarter of natural forests have been cleared by humans to make way for other land-uses, with changes to forest cover projected to continue. The climate impact of land-use change (LUC) is dependent upon the relative strength of several biogeophysical and biogeochemical effects. In addition to affecting the surface albedo and exchanging carbon dioxide (CO2) and moisture with the atmosphere, vegetation emits biogenic volatile organic compounds (BVOCs), altering the formation of short-lived climate forcers (SLCFs) including aerosol, ozone (O3) and methane (CH4)...
June 6, 2017: Faraday Discussions
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