RESUMEN
We use the free radical polymerization initiator 4,4'-azobis(cyanovaleric acid) coordinated to the open metal sites of metal-organic frameworks (MOFs) to give rise to highly uniform MOF/polymer hybrids. We demonstrate this strategy on two robust zirconium MOFs (NU-1000 and MOF-808), which are the most effective catalysts for degradation of chemical warfare nerve agents. The resulting hybrid materials maintain their hydrolytic catalytic activity and have substantially improved adhesion to polypropylene and activated carbon textile fibers, yielding highly robust MOF/polymer/textile hybrid systems. These composites are suitable for the green production of active protective clothing and filters capable of detoxifying organophosphorus warfare agents.
RESUMEN
We report the controlled synthesis of thin films of prototypical zirconium metal-organic frameworks [Zr6O4(OH)4(benzene-1,4-dicarboxylate-2-X)6] (X = H, UiO-66 and X = NH2, UiO-66-NH2) over the external surface of shaped carbonized substrates (spheres and textile fabrics) using a layer-by-layer method. The resulting composite materials contain metal-organic framework (MOF) crystals homogeneously distributed over the external surface of the porous shaped bodies, which are able to capture an organophosphate nerve agent simulant (diisopropylfluorophosphate, DIFP) in competition with moisture (very fast) and hydrolyze the P-F bond (slow). This behavior confers the composite material self-cleaning properties, which are useful for blocking secondary emission problems of classical protective equipment based on activated carbon.
RESUMEN
A series of Ce/Zr mixed-metal-organic frameworks with different topology/connectivity, namely, Ce/Zr-UiO-66 (U01, U02, and U03) (fcu (12-c)), Ce/Zr-DUT-67-PZDC (D01 and D02) (reo (8-c)), and Ce/Zr-MOF-808 (M01, M02, and M03) (spn (6-c)) were evaluated toward the detoxification of toxic nerve agent model diisopropylfluorophosphate (DIFP) at room temperature in unbuffered aqueous solution. Noteworthily, the catalytic rate for P-F bond cleavage increased with increasing Ce/Zr molar ratio. A further increase in catalytic activity can be achieved by Mg(OMe)2 doping of the mixed-metal MOFs as exemplified with M01@Mg(OMe)2 and M02@Mg(OMe)2 systems. The results show that Mg(OMe)2 incorporation into the mesoporous cavities of M01 and M02 give rise to P-F hydrolytic degradation half-lives of nearly 5 and 2 min with 100% degradation of DIFP after 55 and 65 min for M01@Mg(OMe)2 1:2 and M02@Mg(OMe)2 1:4, respectively.
Asunto(s)
Cerio/química , Isoflurofato/química , Estructuras Metalorgánicas/química , Agentes Nerviosos/química , Circonio/química , Catálisis , Hidrólisis , Estructura Molecular , Tamaño de la Partícula , Porosidad , Propiedades de SuperficieRESUMEN
UiO-66, MOF-808 and NU-1000 metal-organic frameworks exhibit a differentiated reactivity toward [Mg(OMe)2(MeOH)2]4 related to their pore accessibility. Microporous UiO-66 remains unchanged while mesoporous MOF-808 and hierarchical micro/mesoporous NU-1000 materials yield doped systems containing exposed MgZr5O2(OH)6 clusters in the mesoporous cavities. This modification is responsible for a remarkable enhancement of the catalytic activity toward the hydrolytic degradation of P-F and P-S bonds of toxic nerve agents, at room temperature, in unbuffered aqueous solutions.
Asunto(s)
Magnesio/química , Estructuras Metalorgánicas/química , Agentes Nerviosos/química , Circonio/química , Catálisis , Hidrólisis , Modelos Moleculares , Oxidación-Reducción , Tamaño de la Partícula , Porosidad , Propiedades de Superficie , TemperaturaRESUMEN
A series of imine-based covalent organic frameworks decorated in their cavities with different alkynyl, pyrrolidine, and N-methylpyrrolidine functional groups have been synthetized. These materials exhibit catalytic activity in aqueous media for the hydrolytic detoxification of nerve agents, as exemplified with nerve gas simulant diisopropylfluorophosphate (DIFP). These preliminary results suggest imine-based covalent organic frameworks (COFs) as promising materials for detoxification of highly toxic molecules.
RESUMEN
We report the application of a post-synthetic solid-state cation-exchange process to afford a novel 3D MOF with hydrated barium cations hosted at pores able to trigger selective and reversible SO2 adsorption. Computational modelling supports the full reversibility of the adsorption process on the basis of weak supramolecular interactions between SO2 and coordinated water molecules.
RESUMEN
The development of protective self-detoxifying materials is an important societal challenge to counteract risk of attacks employing highly toxic chemical warfare agents (CWAs). In this work, we have developed bifunctional zirconium metal-organic frameworks (MOFs) incorporating variable amounts of nucleophilic amino residues by means of formation of the mixed ligand [Zr6O4(OH)4(bdc)6(1-x)(bdc-NH2)6x] (UiO-66-xNH2) and [Zr6O4(OH)4(bpdc)6(1-x)(bpdc-(NH2)2)6x] (UiO-67-x(NH2)2) systems where bdc = benzene-1,4-dicarboxylate; bdc-NH2= benzene-2-amino-1,4-dicarboxylate; bpdc = 4,4'-biphenyldicarboxylate; bpdc-(NH2)2 = 2,2'-diamino-4,4'-biphenyldicarboxylate and x = 0, 0.25, 0.5, 0.75, 1. In a second step, the UiO-66-xNH2 and UiO-67-x(NH2)2 systems have been postsynthetically modified by introduction of highly basic lithium tert-butoxide (LiOtBu) on the oxohydroxometallic clusters of the mixed ligand MOFs to yield UiO-66-xNH2@LiOtBu and UiO-67-x(NH2)2@LiOtBu materials. The results show that the combination of pre and postsynthetic modifications on these MOF series gives rise to fine-tuning of the catalytic activity toward the hydrolytic degradation of both simulants and real CWAs in unbuffered aqueous solutions. Indeed, UiO-66-0.25NH2@LiOtBu is able to hydrolyze both CWAs simulants (diisopropylfluorophosphate (DIFP), 2-chloroethylethylsulfide (CEES), and real CWAs (soman (GD), sulfur mustard (HD)) quickly in aqueous solution. These results are related to a suitable combination of robustness, nucleophilicity, basicity, and accessibility to the porous framework.
