Search results for "organic frameworks"
showing 10 items of 95 documents
MOF-Mediated Synthesis of Supported Fe-Doped Pd Nanoparticles under Mild Conditions for Magnetically Recoverable Catalysis**
2020
Metal–organic framework (MOF)-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, with Pd and Fe as the metal components, by the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fe-doped Pd nanoparticles that, in turn, are supported on iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR and Raman spectroscopy, TEM, XPS, and XAS. The performance of this nanocomposite as an heterogeneous cat…
Recent Progress in the Development of Composite Membranes Based on Polybenzimidazole for High Temperature Proton Exchange Membrane (PEM) Fuel Cell Ap…
2020
[EN] The rapid increasing of the population in combination with the emergence of new energy-consuming technologies has risen worldwide total energy consumption towards unprecedent values. Furthermore, fossil fuel reserves are running out very quickly and the polluting greenhouse gases emitted during their utilization need to be reduced. In this scenario, a few alternative energy sources have been proposed and, among these, proton exchange membrane (PEM) fuel cells are promising. Recently, polybenzimidazole-based polymers, featuring high chemical and thermal stability, in combination with fillers that can regulate the proton mobility, have attracted tremendous attention for their roles as PE…
Exploiting Reaction-Diffusion Conditions to Trigger Pathway Complexity in the Growth of a MOF.
2021
Coordination polymers (CPs), including metal–organic frameworks (MOFs), are crystalline materials with promising applications in electronics, magnetism, catalysis, and gas storage/separation. However, the mechanisms and pathways underlying their formation remain largely undisclosed. Herein, we demonstrate that diffusion-controlled mixing of reagents at the very early stages of the crystallization process (i.e., within ≈40 ms), achieved by using continuous-flow microfluidic devices, can be used to enable novel crystallization pathways of a prototypical spin-crossover MOF towards its thermodynamic product. In particular, two distinct and unprecedented nucleation-growth pathways were experimen…
Surface functionalization of metal-organic frameworks for improved moisture resistance
2018
Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategie…
Hybrid Inorganic‐Organic White Light Emitting Diodes
2020
This chapter reviews the state of the art of materials, technologies, characterizations, process and challenges concerning hybrid white light‐emitting diodes (LEDs). Here, for a “hybrid LED” we mean a device based on a layer of organic phosphors (or a mix of inorganic and organic ones) pumped by a high‐energy inorganic LED. Light is emitted by a frequency down‐conversion (sometimes simply named color‐conversion) process. Benefits and weak spots of this technology are investigated with a special attention for the materials involved into the process of frequency down‐conversion, in order to envisage the future impact of the hybrid lighting technology among the well‐established inorganic ones.
Unveiled the Source of the Structural Instability of HKUST Powders upon Mechanical Compaction: Definition of a Fully Preserving Tableting Method
2019
Metal–organic frameworks (MOFs) are getting closer to finally being used in commercial applications. In order to maximize their packing density, mechanical strength, stability in reactive environments, and many other properties, the compaction of MOF powders is a fundamental step for the application field of research of these extraordinary materials. In particular, HKUST-1 is among the most promising and studied MOF. Contrary to what reported so far in the literature, here we prove that the tableting of HKUST-1 powders without any damage of the lattice is possible and easy to get. For the first time, this kind of investigation has been performed exploiting its peculiar magnetic properties w…
Tetrazine Linkers as Plug-and-Play Tags for General Framework Functionalization and C60 Conjugation
2022
The value of covalent post-synthetic modification in expanding the chemistry and pore versatility of reticular solids is well documented. Here we use mesoporous crystals of UiO-68-TZDC to demonstrate the value of tetrazine connectors for all-purpose inverse electron-demand Diels-Alder ligation chemistry. Our results suggest a positive effect of tetrazine reticulation over its reactivity for quantitative one-step functionalization with a broad scope of alkene or alkyne dienophiles into pyridazine and dihydropyridazine frameworks. This permits generating multiple pore environments with diverse chemical functionalities and the expected accessible porosities, that is also extended to the synthe…
Chemical Engineering of Photoactivity in Heterometallic Titanium–Organic Frameworks by Metal Doping
2018
[EN] We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post-synthetic metallation of MOFs, our approach is well-fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band-gap and electronic properties of the porous solid. Changes in the band-gap are also rationa…
Bioinspired Metal-Organic Frameworks in Mixed Matrix Membranes for Efficient Static/Dynamic Removal of Mercury from Water
2020
The mercury removal efficiency of a novel metal-organic framework (MOF) derived from the amino acid S-methyl-L-cysteine is presented and the process is characterized by single-crystal X-ray crystallography. A feasibility study is further presented on the performance of this MOF and also that of another MOF derived from the amino acid L-methionine when used as the sorbent in mixed matrix membranes (MMMs). These MOF-based MMMs exhibit high efficiency and selectivity in both static and dynamic regimes in the removal of Hg2+ from aqueous environments, due to the high density of thioalkyl groups decorating MOF channels. Both MMMs are capable to reduce different concentration of the pollutant to …
A Biocompatible Aspartic-Decorated Metal–Organic Framework with Tubular Motif Degradable under Physiological Conditions
2021
Achieving a precise control of the final structure of metal–organic frameworks (MOFs) is necessary to obtain desired physical properties. Here, we describe how the use of a metalloligand design strategy and a judicious choice of ligands inspired from nature is a versatile approach to succeed in this challenging task. We report a new porous chiral MOF, with the formula Ca5II{CuII10[(S,S)-aspartamox]5}·160H2O (1), constructed from Cu2+ and Ca2+ ions and aspartic acid-decorated ligands, where biometal Cu2+ ions are bridged by the carboxylate groups of aspartic acid moieties. The structure of MOF 1 reveals an infinite network of basket-like cages, built by 10 crystallographically distinct Cu(II…