Search results for "Imidazolate"
showing 10 items of 19 documents
Nanoparticle-Directed Metal–Organic Framework/Porous Organic Polymer Monolithic Supports for Flow-Based Applications
2017
A two-step nanoparticle-directed route for the preparation of macroporous polymer monoliths for which the pore surface is covered with a metal–organic framework (MOF) coating has been developed to facilitate the use of MOFs in flow-based applications. The flow-through monolithic matrix was prepared in a column format from a polymerization mixture containing ZnO-nanoparticles. These nanoparticles embedded in the precursor monolith were converted to MOF coatings via the dissolution–precipitation equilibrium after filling the pores of the monolith with a solution of the organic linker. Pore surface coverage with the microporous zeolitic imidazolate framework ZIF-8 resulted in an increase in su…
Diffusion Control in Single-Site Zinc Reticular Amination Catalysts.
2020
Zn-containing metal-organic frameworks have been used for the first time as heterogeneous catalysts in the amination of C-Cl bonds. The use of extended bis(pyrazolate) linkers can generate highly porous architectures, which favor the diffusion of amines to the confined spaces with respect to other imidazolate frameworks with narrower pore windows. The N4Zn nodes of the Zn-reticular framework show comparable activity to state-of-the-art homogeneous Zn amination catalysts, avoiding the use of basic conditions, precious metals, or other additives. This is combined with long-term activity and stability upon several reaction cycles, without contamination of the reaction product. ispartof: INORGA…
Integrated Cleanroom Process for the Vapor-Phase Deposition of Large-Area Zeolitic Imidazolate Framework Thin Films
2019
Chemistry of materials XX(XX), acs.chemmater.9b03435 (2019). doi:10.1021/acs.chemmater.9b03435
Cation influence in adsorptive propane/propylene separation in ZIF-8 (SOD) topology
2019
Separation of propylene/propane is one of the most challenging and energy consuming processes in the chemical industry. Propylene demand is increasing and a 99.5% purity is required for industrial purposes. Adsorption based solutions are the most promising alternatives to improve the economical/energetic efficiency of the process. Zeolitic Imidazolate Frameworks (ZIFs) combine the desired characteristics from both MOFs and zeolites: tunability and flexibility from metal organic frameworks, and exceptional thermal and chemical stability from zeolites. In order to enlighten the role of the cation in the sodalite ZIF-8 framework for propane/propylene separation, dynamic breakthrough measuremen…
Effect of linker distribution in the photocatalytic activity of multivariate mesoporous crystals
2021
The use of Metal-Organic Frameworks as crystalline matrices for the synthesis of multiple component or multivariate solids by the combination of different linkers into a single material has emerged as a versatile route to tailor the properties of single-component phases or even access new functions. This approach is particularly relevant for Zr6-MOFs due to the synthetic flexibility of this inorganic node. However, the majority of materials are isolated as polycrystalline solids, which are not ideal to decipher the spatial arrangement of parent and exchanged linkers for the formation of homogeneous structures or heterogeneous domains across the solid. Here we use high-throughput methodologi…
Low-temperature optical spectroscopy of cobalt in Cu,Co superoxide dismutase: a structural dynamics study of the solvent-unaccessible metal site.
1995
The temperature dependence (300 to 10 K) of the electronic absorption spectra of the cobalt chromophore in bovine superoxide dismutase (SOD) having the native Zn(II) ion selectivity replaced by Co(II) has been investigated in four different derivatives: Cu(II),Co(II) SOD, N3(-)-Cu(II), Co(II) SOD, Cu(I),Co(II) SOD, and E,Co(II) SOD in which the copper ion has been selectively removed. In the Cu(II),Co(II) SOD, the cobalt spectrum is characterized at room temperature by three bands centered at 18,472, 17,670, and 16,793 cm-1; the low-frequency band is split, at low temperatures, into two components, indicating a lower symmetry contribution to a predominantly tetrahedral crystal field. Additi…
Solvent-Free Synthesis of a Pillared Three-Dimensional Coordination Polymer with Magnetic Ordering
2015
A new magnetic coordination polymer, [Fe(bipy)(im)2] (bipy = 4,4-bipyridine and im = imidazole), has been synthesized in a solvent-free reaction. Structural analysis reveals a pillared 3D coordination polymer composed by neutral layers, formed by iron(II) and imidazolate linkers, interconnected by bipy ligands which serve as pillars. Magnetic measurements show that the material magnetically orders at low temperatures (Tc = 14.5 K) as a weak ferromagnet, likely due to a spin canting.
Iron( ii ) and cobalt( ii ) complexes based on anionic phenanthroline-imidazolate ligands: reversible single-crystal-to-single-crystal transformations
2018
A series of low-spin FeII and CoII complexes based on phenanthroline-imidazolate (PIMP) ligands are reported. The FeII complex (H9O4)[Fe(PIMP)3]·(C4H10O)2(H2O) (1a) shows reversible crystalline phase transformations to afford two new phases (H9O4)[Fe(PIMP)3]·(H2O) (1b) and (H9O4)[Fe(PIMP)3]·(C8H18O)(C4H10O)(H2O) (1c) by release of diethyl ether and absorption of diethyl/dibutyl ether, respectively. This reversible uptake/release of solvent molecules is a clear example of single-crystal-to-single-crystal transformation involving a discrete metal complex. On the other hand, the corresponding CoII complex (H9O4)[Co(PIMP)3]·(C4H10O)2(H2O)2 (2) does not exhibit similar phase transformations. In …
Multivariate sodalite Zeolitic Imidazolate frameworks: a direct solvent-free synthesis
2021
Different mixed-ligand Zeolitic Imidazolate Frameworks (ZIFs) with sodalite topology, i.e. isoreticular to ZIF-8, unachievable by conventional synthetic routes, have been prepared using a solvent-free methodology. In particular, the versatility of this method is demonstrated with three different metal centres (Zn, Co and Fe) and binary combinations of three different ligands (2-methylimidazole, 2-ethylimidazole and 2-methylbenzimidazole). One combination of ligands, 2-ethylimidazole and 2-methylbenzimidazole, results in the formation of SOD frameworks for the three metal centres despite this topology not being obtained for the individual ligands. Theoretical calculations confirm that this t…
Solvent-Free Synthesis of ZIFs Compatible with Iron: A Route Towards the Elusive Fe(II) Analogue of ZIF-8
2019
Herein we report the synthesis of an elusive metal-organic framework, the iron(II) analogue of ZIF-8, with formula Fe(2-methylimidazolate)2, here denoted as MUV-3. The preparation of this highly interesting porous material, inaccessible by common synthetic procedures, occurs in a solvent-free reaction upon addition of an easily detachable template molecule, yielding single crystals of MUV-3. This methodology is extensive to other metals and imidazolate derivatives, allowing the preparation of ZIF-8, ZIF-67 and other unprecedented iron(II) ZIFs, Fe(2-ethylimidazolate)2 and Fe(2-methylbenzimidazolate)2. The different performance of MUV-3 towards NO sorption, compared to ZIF-8, results from th…