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1.
Chem Commun (Camb) ; 56(55): 7657-7660, 2020 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-32520025

RESUMO

The isolation of high-quality flakes of 2D MOFs in large amounts remains a challenge. In this work, we obtained nanosheets for a whole family of Fe-based magnetic MOFs, MUV-1-X, through a liquid exfoliation procedure. High-quality crystalline layers with lateral sizes of 8 µm and thicknesses of 4 nm, which retain the structural integrity and magnetic properties, are obtained.

2.
J Am Chem Soc ; 141(17): 7173-7180, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30973716

RESUMO

Herein we report the synthesis of an elusive metal-organic framework, the iron(II) analogue of ZIF-8 with the 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 can be extended to other metals and imidazolate derivatives, allowing the preparation of ZIF-8, ZIF-67, and the unprecedented iron(II) ZIFs Fe(2-ethylimidazolate)2 and Fe(2-methylbenzimidazolate)2. The different performance of MUV-3 toward NO sorption, in comparison to ZIF-8, results from the chemisorption of NO molecules, which also causes a gate-opening behavior. Finally, the controlled pyrolysis of MUV-3 results in a N-doped graphitic nanocomposite that exhibits extraordinary performance for the oxygen evolution reaction (OER), with low overpotential at different current densities (316 mV at 10 mA cm-2), low Tafel slope (37 mV per decade), high maximum current density (710 mA cm-2 at 2.0 V vs RHE), and great durability (15 h).

3.
Chemistry ; 24(47): 12426-12432, 2018 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-29989253

RESUMO

Modification of the magnetic properties in a solid-state material upon external stimulus has attracted much attention in the recent years for their potential applications as switches and sensors. Within the field of coordination polymers, gas sorption studies typically focus on porous solids, with the gas molecules accommodating in the channels. Here we present a 1D non-porous coordination polymer capable of incorporating HCl gas molecules, which not only causes a reordering of its atoms in the solid state but also provokes dramatic changes in the magnetic behavior. Subsequently, a further solid-gas transformation can occur with the extrusion of HCl gas molecules causing a second structural rearrangement, which is also accompanied by modification in the magnetic path between the metal centers. Unequivocal evidence of the two-step magnetostructural transformation is provided by X-ray single-crystal diffraction.

4.
Polymers (Basel) ; 8(5)2016 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-30979261

RESUMO

The encapsulation of functional molecules inside porous coordination polymers (also known as metal-organic frameworks, MOFs) has become of great interest in recent years at the field of multifunctional materials. In this article, we present a study of the effects of size and charge in the anion exchange process of a Gd based MOF, involving molecular species like polyoxometalates (POMs), and [AuCl4]-. This post-synthetic modification has been characterized by IR, EDAX, and single crystal diffraction, which have provided unequivocal evidence of the location of the anion molecules in the framework.

5.
Inorg Chem ; 54(21): 10490-6, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-26468913

RESUMO

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.


Assuntos
Magnetismo , Polímeros/química , Solventes/química , Cristalografia por Raios X , Termogravimetria
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