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metal-organic framework

Mathieu Bosch, Shuai Yuan, William Rutledge, Hong-Cai Zhou
Metal-organic frameworks (MOFs) are a category of porous materials that offer unparalleled control over their surface areas (demonstrated as higher than for any other material), pore characteristics, and functionalization. This allows them to be customized for exceptional performance in a wide variety of applications, most commonly including gas storage and separation, drug delivery, luminescence, or heterogeneous catalysis. In order to optimize biomimicry, controlled separations and storage of small molecules, and detailed testing of structure-property relationships, one major goal of MOF research is "rational design" or "pore engineering", or precise control of the placement of multiple functional groups in pores of chosen sizes and shapes...
March 28, 2017: Accounts of Chemical Research
Wenjing Xu, Mingsheng Wang, Zhiwei Li, Xiaojing Wang, Yongqiang Wang, Mingyang Xing, Yadong Yin
When nanocrystals are made to undergo chemical transformations, there are often accompanying large mechanical deformations and changes to overall particle morphology. These effects can constrain development of multistep synthetic methods through loss of well-defined particle morphology and functionality. Here, we demonstrate a surface protection strategy for solution phase chemical conversion of colloidal nanostructures that allows for preservation of overall particle morphology despite large volume changes...
March 28, 2017: Nano Letters
Sören Zint, Daniel Ebeling, Tobias Schlöder, Sebastian Ahles, Doreen Mollenhauer, Hermann A Wegner, Andre Schirmeisen
The in-depth knowledge about on-surface reaction mechanisms is crucial for the tailor-made design of covalently bonded organic frameworks, for applications such as nanoelectronic or -optical devices. Latest developments in atomic force microscopy, which rely on functionalizing the tip with single CO molecules at low temperatures allow to image molecular systems with submolecular resolution. Here, we are using this technique to study the complete reaction pathway of the on-surface Ullmann-type coupling between bromotriphenylene molecules on a Cu(111) surface...
March 27, 2017: ACS Nano
A Paulina Gómora-Figueroa, Jarad A Mason, Miguel I Gonzalez, Eric D Bloch, Katie R Meihaus
The reaction of ZrCl4 with 2',3',5',6'-tetramethylamino-p-terphenyl-4,4″-dicarboxylic acid (H2tpdc-4CH2NH2·3HCl) in the presence of NaF affords Zr6O4(OH)2.1F1.9(tpdc-4CH2NH2·3HCl)6 (1), which is a new member of the Zr6O4(OH)4(dicarboxylate linker)12 or UiO-68 family, and exhibits high porosity with BET and Langmuir surface areas of 1910 m(2)/g and 2220 m(2)/g, respectively. Remarkably, fluoride ion incorporation in the zirconium clusters results in increased thermal stability, marking the first example of enhancement in the stability of a UiO framework by this defect-restoration approach...
March 27, 2017: Inorganic Chemistry
Michio Matsumoto, Raghunath R Dasari, Woojung Ji, Cameron H Feriante, Timothy C Parker, Seth R Marder, William R Dichtel
Imine-linked two-dimensional covalent organic frameworks (2D COFs) are crystalline polymer networks with enhanced stability and broader monomer scope compared to boronate ester-linked systems. They are traditionally prepared by condensing polyfunctional aldehydes and amines at elevated temperature in a mixture of organic solvents and aqueous CH3CO2H, which catalyzes imine formation and exchange. Under these conditions, an amorphous imine-linked polymer network precipitates quickly and then crystallizes after extended reaction times (hours to days)...
March 27, 2017: Journal of the American Chemical Society
Daiqin Chen, Dongzhi Yang, Casey A Dougherty, Weifei Lu, Hongwei Wu, Xianran He, Ting Cai, Marcian E Van Dort, Brian D Ross, Hao Hong
Nanoscale metal-organic frameworks (nMOF) materials represent an attractive tool for various biomedical applications. Due to the chemical versatility, enormous porosity, and tunable degradability of nMOFs, they have been adopted as carriers for delivery of imaging and/or therapeutic cargos. However, the relatively low stability of most nMOFs has limited practical in vivo applications. Here we report the production and characterization of an intrinsically radioactive UiO-66 nMOF ((89)Zr-UiO-66) with incorporation of positron-emitting isotope zirconium-89 ((89)Zr)...
March 28, 2017: ACS Nano
Edgar Mijangos, Souvik Roy, Sonja Pullen, Reiner Lomoth, Sascha Ott
The development of a reliable platform for the electrochemical characterization of a redox-active molecular diiron complex, [FeFe], immobilized in a non-conducting metal organic framework (MOF), UiO-66, based on glassy-carbon electrodes is reported. Voltammetric data with appreciable current responses can be obtained by the use of multiwalled carbon nanotubes (MWCNT) or mesoporous carbon (CB) additives that function as conductive scaffolds to interface the MOF crystals in "three-dimensional" electrodes. In the investigated UiO-66-[FeFe] sample, the low abundance of [FeFe] in the MOF and the intrinsic insulating properties of UiO-66 prevent charge transport through the framework, and consequently, only [FeFe] units that are in direct physical contact with the electrode material are electrochemically addressable...
March 27, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
N Scott Bobbitt, Matthew L Mendonca, Ashlee J Howarth, Timur Islamoglu, Joseph T Hupp, Omar K Farha, Randall Q Snurr
Owing to the vast diversity of linkers, nodes, and topologies, metal-organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water...
March 27, 2017: Chemical Society Reviews
Yingda Jiang, Jingtai Li, Guirong Su, Nicola Ferri, Wei Liu, Alexandre Tkatchenko
Understanding the binding mechanisms for aromatic molecules on transition-metal surfaces, especially with defects such as vacancies, steps, and kinks, is a major challenge in designing functional interfaces for organic devices. One important parameter in the performance of organic/inorganic devices is the barrier of charge carrier injection. In case of a metallic electrode, tuning the electronic interface potential or the work function for electronic level alignment is crucial. Here, we use density-functional theory (DFT) calculations with van der Waals (vdW) interactions treated with both screened pairwise and many-body dispersion (MBD) methods, to systematically study the interactions of benzene with a variety of stepped surfaces...
March 27, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ze-Yu Jiang, Hai-Ling Liu, Saud Asif Ahmed, Sumaira Hanif, Shi-Bin Ren, Jing-Juan Xu, Hong-Yuan Chen, Xing-Hua Xia, Kang Wang
A crack-free sub-nanometer composite structure for the study of ion transfer was constructed by in situ growth of ZIF-90 [Zn(ICA)2 , ICA=Imidazole-2-carboxaldehyde] on the tip of a glass nanopipette. The potential-driven ion transfer through the sub-nanometer channels in ZIF-90 is strongly influenced by the pH of the solution. A rectification ratio over 500 is observed in 1 m KCl solution under alkaline conditions (pH 11.58), which is the highest value reported under such a high salt concentration. Fluorescence experiments show the super-high rectification ratio under alkaline conditions results from the strong electrostatic interaction between ions and the sub-nanometer channels of ZIF-90...
March 27, 2017: Angewandte Chemie
Wenxiu Yang, Xiangjian Liu, Lulu Chen, Liang Liang, Jianbo Jia
A Co-N doped 3D carbon microsphere/nanofiber hybrid was produced by electrospinning. We can effectively control the morphology transformation from a pearl necklace-like nanofiber to a microsphere/nanofiber hybrid. The hybrid shows Pt-like oxygen reduction reaction activity both in acidic and basic solutions, making it one of the best non-noble metal oxygen catalysts.
March 27, 2017: Chemical Communications: Chem Comm
Necati Kaleli, Duygu Saraç
STATEMENT OF PROBLEM: Most studies evaluating dental laser sintering systems have focused on the marginal accuracy of the restorations. However, the bond strength at the metal-ceramic interface is another important factor that affects the survival of restorations, and currently, few studies focus on this aspect. PURPOSE: The purpose of this in vitro study was to compare the porcelain bond strength of cobalt-chromium (Co-Cr) metal frameworks prepared by using the conventional lost-wax technique, milling, direct metal laser sintering (DMLS), and laser cusing, a direct process powder-bed system...
March 23, 2017: Journal of Prosthetic Dentistry
Matthew J Cliffe, Elizabeth Castillo-Martinez, Yue Wu, Jeongjae Lee, Alexander C Forse, Francesca C N Firth, Peyman Z Moghadam, David Fairen-Jimenez, Michael W Gaultois, Joshua A Hill, Oxana V Magdysyuk, Ben Slater, Andrew L Goodwin, Clare P Grey
We report a hafnium containing MOF, hcp UiO-67(Hf), which is a defective layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its low- ered ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed 'double cluster', analogous to the condensation of coor- dination polyhedra in oxide frameworks. In oxide frameworks variable stoichiometry can lead to more complex defect structures, e.g. crystallographic shear planes or mod- ules with differing compositions, which can be the source of further chemical reactivity; likewise the layered hcp UiO-67 can react further to form two-dimensional nanosheets...
March 27, 2017: Journal of the American Chemical Society
Man Zhao, Yiqin Xie, Hemei Chen, Chunhui Deng
Zeolitic imidazolate frameworks (ZIFs) are composed of tetrahedral transition metal ions and imidazolate type organic linkers. This kind of metal organic frameworks (MOFs) combines the unique properties of both zeolites and MOFs. Furthermore, ZIFs can be assembled under mild biocompatible conditions. These advantages make them be primarily studied for biochemical analysis. In this work, polydopamine-modified hydrophilic magnetic ZIFs were synthesized in a simple and mild way for the efficient extraction of low-abundance peptides...
May 15, 2017: Talanta
Lili Xiao, Ruiyu Xu, Qunhui Yuan, Fu Wang
Benefit from the advantages in costless, simplicity and efficiency, solvent exfoliation has been widely used in preparation of two-dimensional nanosheets with enhanced performances in electronics, photonics, and catalysis. In this work, solvent exfoliation was first applied to prepare exfoliated porous carbon (EPC) from an isoreticular metal-organic framework-8 (IRMOF-8) derived porous carbon (DPC). The obtained EPC with high surface area (1854m(2)g(-1)) and improved dispersibility was used as electrode modifier for glassy carbon electrode (GCE) in square wave voltammetry (SWV) detection of chloramphenicol (CAP)...
May 15, 2017: Talanta
Siyuan Wu, Hao Huang, Xun Feng, Cuicui Du, Wenbo Song
Herein, via one-step pyrolysis of glucose, dicyandiamide (DCDA) and Fe containing metal-organic framework (Fe-MOF), small Fe3C nanoparticles were in-situ decorated in 3D porous network of N-rich graphene (NGr). The Fe-MOF served as size regulating precursor, layered g-C3N4 (derived from pyrolysis of DCDA) acted as not only a template to guide the growth of small Fe3C nanoparticles, but also the carbon source for 3D porous NGr network. The intrinsic peroxidase-like catalytic activity of Fe3C/NGr was unpredictably discovered, by taking the oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB) with H2O2 as a protocol...
May 15, 2017: Talanta
Wenfei Dong, Liaoyuan Yang, Yuming Huang
A facile and rapid post-synthetic strategy was proposed to prepare a glycine functionalized MIL-53(Fe), namely glycine-MIL-53(Fe), by a simple mixing of water dispersible MIL-53(Fe) and glycine. The FT-IR, SEM, XRD and zeta potential were used to characterize the glycine-MIL-53(Fe). The result showed that glycine post-synthetic modification of MIL-53(Fe) did not change in the morphology and crystal structure of MIL-53(Fe). Interestingly, compared with MIL-53(Fe), the glycine-MIL-53(Fe) exhibits an enhanced peroxidase-like activity, which could catalyze the oxidation of TMB by H2O2 to produce an intensive color reaction...
May 15, 2017: Talanta
Boushra Mortada, Tamara Abou Matar, Aya Sakaya, Hala Atallah, Zeinab Kara Ali, Pierre Karam, Mohamad Hmadeh
Metal-organic frameworks (MOFs) have emerged as an important class of hybrid organic-inorganic materials. One of the reasons they have gained remarkable attention is attributed to the possibility of altering them by postsynthetic modification, thereby providing access to new and novel advanced materials. MOFs have been applied in catalysis, gas storage, gas separation, chemical sensing, and drug delivery. However, their bactericidal use has rarely been explored. Herein, we developed a two-step process for the synthesis of zirconium-based MOFs metalated with silver cations as a potent antibacterial agent...
March 24, 2017: Inorganic Chemistry
S M J Rogge, A Bavykina, J Hajek, H Garcia, A I Olivos-Suarez, A Sepúlveda-Escribano, A Vimont, G Clet, P Bazin, F Kapteijn, M Daturi, E V Ramos-Fernandez, F X Llabrés I Xamena, V Van Speybroeck, J Gascon
Heterogeneous single-site catalysts consist of isolated, well-defined, active sites that are spatially separated in a given solid and, ideally, structurally identical. In this review, the potential of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) as platforms for the development of heterogeneous single-site catalysts is reviewed thoroughly. In the first part of this article, synthetic strategies and progress in the implementation of such sites in these two classes of materials are discussed...
March 24, 2017: Chemical Society Reviews
Xiaowei Ma, Fan Feng, Yang Yang, Xueping Dang, Jianlin Huang, Huaixia Chen
Fe3O4@MIL-100 (MIL, Material Institut Lavoisier) core-shell magnetic microspheres were prepared and applied as the sorbent for the magnetic solid phase extraction (MSPE) of N,N-diethyl-m-toluamide (DEET) in baby toilet water for the first time. The synthesized magnetic metal-organic frameworks were characterized by transmission electron microscope, infrared spectroscopy and thermogravimetric analysis. The functionalized magnetic microparticles showed excellent dispersibility in aqueous solution. The MSPE conditions were investigated in detail...
March 3, 2017: Journal of Chromatographic Science
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