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metal-organic framework

Pravas Deria, Diego A Gómez-Gualdrón, Idan Hod, Randall Q Snurr, Joseph T Hupp, Omar K Farha
Catalytic activity for acyl transfer from N-acetylimidazole (NAI) to different pyridylcarbinol (PC) regioisomers (2-PC, 3-PC, and 4-PC) is demonstrated for a set of topologically diverse, zirconium-based (porphinato)zinc metal-organic frameworks (MOFs). The MOFs studied are PCN-222, MOF-525, and NU-902, which are based on the csq, ftw, and scu topologies, respectively. The experimentally obtained reaction kinetics are discussed in light of molecular modeling results. The catalytic activity is shown to vary across the series of MOFs due to the different extent to which each topology facilitates reactant preconcentration and alignment of PC and NAI via coordination to framework porphyrin sites (orientation effects)...
October 21, 2016: Journal of the American Chemical Society
Radwan Elzein, Chun-Min Chang, Inna Ponomareva, Wen-Yang Gao, Shengqian Ma, Rudy Schlaf
Metal-organic frameworks (MOFs) deposited from solution have the potential to form 2-dimensional supramolecular thin films suitable for molecular electronic applications. However, the main challenges lie in achieving selective attachment to the substrate surface, and the integration of organic conductive ligands into the MOF structure to achieve conductivity. The presented results demonstrate that photoemission spectroscopy combined with preparation in a system-attached glovebox can be used to characterize the electronic structure of such systems...
October 21, 2016: ACS Applied Materials & Interfaces
Subhadip Goswami, Lin Ma, Alex B F Martinson, Michael R Wasielewski, Omar K Farha, Joseph T Hupp
Owing to their ability to act as light-harvesting scaffolds, porphyrin-containing metal-organic frameworks (MOFs) are in the forefront of research on the application of highly ordered molecular materials to problems in solar-energy conversion. In this work, solvent assisted linker exchange (SALE) is performed on a pillared paddlewheel porphyrin containing MOF thin film to collapse a 3D-framework to a 2D-framework. The change in dimensionality of the framework is confirmed by a decrease in the film thickness, the magnitude of which is in agreement with crystallographic parameters for related bulk materials...
October 21, 2016: ACS Applied Materials & Interfaces
Qingchun Xia, Yan Liu, Zijian Li, Wei Gong, Yong Cui
A porous Cr(salen)-MOF can serve as an efficient and effective heterogeneous catalyst for a series of important asymmetric transformations including the Nazarov cyclization, aminolysis reaction, and Diels-Alder and hetero Diels-Alder reactions, resulting in comparable or superior diastereo- or enantioselectivity with respect to the corresponding homogeneous systems.
October 21, 2016: Chemical Communications: Chem Comm
Zhong-Jie Wang, Ling Qin, Jin-Xi Chen, He-Gen Zheng
Two luminescent Cd(II) metal-organic frameworks (MOFs) were prepared from electron-rich π-conjugated fluorescent ligands. They are isostructural with sql nets. Their strong luminescences can be quenched by a series of nitroaromatic explosives. Notably, MOF 1 shows highly selective and sensitive detection of 4-nitrophenol (4-NP), while MOF 2 exhibits good responses toward picric acid (PA) compared with other nitroaromatic explosives. This different order of quenching efficiency is because there are H-bonding interactions between MOF 1 and 4-NP, while MOF 2 lacks these H-bonding interactions...
October 21, 2016: Inorganic Chemistry
Lei Sun, Sarah S Park, Dennis Sheberla, Mircea Dinca
Electrically conductive metal-organic frameworks (MOFs) are emerging as a subclass of porous materials that can have a transformative effect on electronic and renewable energy devices. Systematic advances in these materials depend critically on the accurate and reproducible characterization of their electrical properties. This is made difficult by the numerous techniques available for electrical measurements and the dependence of metrics on device architecture and numerous external variables. These challenges, common to all types of electronic materials and devices, are especially acute for porous materials, whose high surface area make them even more susceptible to interactions with contaminants in the environment...
October 21, 2016: Journal of the American Chemical Society
Benjamin S Gelfand, Racheal P S Huynh, Roger K Mah, George K H Shimizu
A crystalline and permanently porous copper phosphonate monoester framework has been synthesized from a tetraaryl trigonal phosphonate monoester linker. This material has a surface area over 1000 m(2)  g(-1) , as measured by N2 sorption, the highest reported for a phosphonate-based metal-organic framework (MOF). The monoesters result in hydrophobic pore surfaces that give a low heat of adsorption for CO2 and low calculated selectivity for CO2 over N2 and CH4 in binary mixtures. By careful manipulation of synthetic conditions, it is possible to selectively remove some of the monoesters lining the pore to form a hydrogen phosphonate while giving an isomorphous structure...
October 21, 2016: Angewandte Chemie
Hong Sheng Quah, Li Ting Ng, Bruno Donnadieu, Geok Kheng Tan, Jagadese J Vittal
Five lanthanide MOFs with pcu topology have been exfoliated into nanoplatelets of two-dimensional structures via sonication in the dimethylacetamide solvent. These nanosheets are fluorescent under two-photon excitation dominated by the ligand, indicating energy upconversion ability.
October 20, 2016: Inorganic Chemistry
Sorina Motoc, Florica Manea, Adriana Iacob, Alberto Martinez-Joaristi, Jorge Gascon, Aniela Pop, Joop Schoonman
In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP) and diclofenac (DCF) in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF) electrode. The morphological and electrical characterization of modified composite electrode prepared by film casting was studied by scanning electronic microscopy and four-point-probe methods. The electrochemical characterization of the electrode by cyclic voltammetry (CV) was considered the reference basis for the optimization of the operating conditions for chronoamperometry (CA) and multiple-pulsed amperometry (MPA)...
October 17, 2016: Sensors
Hongming He, Jason A Perman, Guangshan Zhu, Shengqian Ma
Carbon dioxide (CO2 ), as the primary greenhouse gas in the atmosphere, triggers a series of environmental and energy related problems in the world. Therefore, there is an urgent need to develop multiple methods to capture and convert CO2 into useful chemical products, which can significantly improve the environment and promote sustainable development. Over the past several decades, metal-organic frameworks (MOFs) have shown outstanding heterogeneous catalytic activity due in part to their high internal surface area and chemical functionalities...
October 20, 2016: Small
G W Peterson, M McEntee, C R Harris, A D Klevitch, A W Fountain, J R Soliz, A Balboa, A J Hauser
Electrical impedance spectroscopy, in conjunction with the metal-organic framework (MOF) UiO-66-NH2, is used to detect trace levels of the explosive simulant 2,6-dinitrotoluene. The combination of porosity and functionality of the MOF provides an effective dielectric structure, resulting in changes of impedance magnitude and phase angle. The promising data indicate that MOFs may be used in low-cost, robust explosive detection devices.
October 20, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Rui-Cheng Gao, Fu-Sheng Guo, Nan-Nan Bai, Yun-Long Wu, Fan Yang, Ji-Ye Liang, Zhen-Jing Li, Yao-Yu Wang
Two new three-dimensional isostructural lanthanide metal-organic frameworks (Ln(III)-MOFs), [LnL(H2O)3]·3H2O·0.75DMF (1-Ln; Ln = Dy(III) and Eu(III) ions, H3L = biphenyl-3'-nitro-3,4',5-tricarboxylic acid, DMF = N,N'-dimethylformamide), were synthesized and characterized. The appearance of temperature-dependent out-of-phase (χ″M) signal reveals that complex 1-Dy displays slow magnetic relaxation behavior with the energy barrier (ΔUeff) of 57 K and a pre-exponential factor (τ0) of 3.89 × 10(-8) s at 1200 Oe direct current field...
October 19, 2016: Inorganic Chemistry
Vahid Sokhanvaran, Saeid Yeganegi
The quantum mechanics (QM) method and Grand Canonical Monte Carlo (GCMC) simulations were performed to study the effect of lithium cation doping on the adsorption and separation of CO2, CH4 and H2 on 2-fold interwoven metal-organic framework (MOF) Zn2(NDC)2(diPyNI). The second order Moller-Plesset (MP2) calculations on the (Li+-diPyNI) cluster model showed that the energetically most favorable lithium binding site is above the pyridine ring side and at a distance of 1.817 Å from the oxygen atom. The results revealed that the adsorption capacity of Zn2(NDC)2(diPyNI) for carbon dioxide is higher than that of hydrogen and methane at room temperature...
October 19, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Yongchul G Chung, Diego A Gómez-Gualdrón, Peng Li, Karson T Leperi, Pravas Deria, Hongda Zhang, Nicolaas A Vermeulen, J Fraser Stoddart, Fengqi You, Joseph T Hupp, Omar K Farha, Randall Q Snurr
Discovery of new adsorbent materials with a high CO2 working capacity could help reduce CO2 emissions from newly commissioned power plants using precombustion carbon capture. High-throughput computational screening efforts can accelerate the discovery of new adsorbents but sometimes require significant computational resources to explore the large space of possible materials. We report the in silico discovery of high-performing adsorbents for precombustion CO2 capture by applying a genetic algorithm to efficiently search a large database of metal-organic frameworks (MOFs) for top candidates...
October 2016: Science Advances
Carla F Pereira, Mário M Q Simões, João P C Tomé, Filipe A Almeida Paz
Porphyrin-based Metal-Organic Frameworks (Por-MOFs) constitute a special branch of the wide MOF family that has proven its own value and high potential in different applications. In this mini-review the application of these materials as catalysts in oxidation reactions is highlighted.
October 12, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Pravas Deria, Jierui Yu, Rajesh P Balaraman, Jamil Mashni, Sandra N White
Highly ordered chromophoric linkers positioned within the metal-organic frameworks (MOFs) have the potential to mimic natural light-harvesting complexes. Herein we report topological control over the photophysical properties of MOFs via modular interchromophoric electronic coupling to manifest different steady-state singlet emission spectra and their corresponding fluorescence lifetimes.
October 18, 2016: Chemical Communications: Chem Comm
Guang-Yao Zhang, Yu-Hong Zhuang, Dan Shan, Guo-Fang Su, Serge Cosnier, Xueji Zhang
A simple and rapid photoelectrochemical (PEC) sensor is developed for the label-free detection of a phosphoprotein (α-casein) based on a zirconium based porphyrinic metal-organic framework (MOF), PCN-222, which exhibits an enhanced photocurrent response towards dopamine under the O2-saturated aqueous media. In this work, in terms of PEC measurements and cyclic voltammetry, the PEC behaviors of PCN-222 in aqueous media were thoroughly investigated for the first time. Additionally, in the virtue of the steric hindrance effect from the coordination of the phosphate groups and inorganic Zr-O clusters as binding sites in PCN-222, this biosensor shows high sensitivity for detecting α-casein and the limit of detection (LOD) is estimated to be 0...
October 18, 2016: Analytical Chemistry
Kevin V Brix, Margaret S Tellis, Anne Crémazy, Chris M Wood
Single metal Biotic Ligand Models (BLMs) have been developed for a number of metals and model organisms. While these BLMs improve our ability to regulate metals in the aquatic environment, in reality, organisms are often simultaneously exposed to metal mixtures. Recently, several attempts have been made to develop mixture BLMs (mBLMs). Some of these models assume competitive interactions between all metals, while others assume only metals with a similar mode of action (e.g., Na(+) or Ca(2+) antagonists) will competitively interact...
October 11, 2016: Aquatic Toxicology
Hui Cao, Siqi Zhu, Chao Yang, Ruiqi Bao, Liuniu Tong, Linrui Hou, Xiaogang Zhang, Changzhou Yuan
Mesoporous hetero-structures have drawn tremendous attention due to their unprecedented inherent advantages in advanced Li-ion batteries (LIBs). In this study, we developed a facile metal-organic-framework-engaged synthetic methodology for large-scale fabrication of two-dimensional (2D) mesoporous hetero-ZnFe2O4/ZnO nanosheets (ZFOZ NSs) with homogeneously dispersed hetero-nanodomains of spinel ZnFe2O4 and ZnO. When evaluated as a promising anode for LIB applications, the resultant 2D ultrathin mesoporous hetero-ZFOZ NSs exhibited extraordinary electrochemical Li storage performance with long-cycle behavior and large reversible capacities for next-generation LIB applications, thanks to the attractive synergetic contributions from ultrathin mesoporous architecture and electroactive bi-component hetero-interfaces at the nanoscale...
October 17, 2016: Nanotechnology
Yung-Han Shih, Kuen-Yun Wang, Brenda T Singco, Chia-Her Lin, Hsi-Ya Huang
In this study, we first demonstrated the effect of two types of metal-organic framework-polymer (MOF-polymer) monoliths on in-tube solid-phase microextraction (IT-SPME) of sulfonamides. Sulfonamides were successfully adsorbed onto MIL-101(Cr)-polymer but were difficult to elute due to these sulfonamides could interact via Lewis acid-base interaction with the presence of Cr(III) coordinatively unsaturated metal sites (CUS). Moreover, the cage-type topology of MIL-101(Cr) that could produce multiple pathways thus complicates the desorption of the test analytes from the sorbent...
October 17, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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