Search results for "frameworks"
showing 10 items of 120 documents
Bidirectional Chemo-Switching of Spin State in a Microporous Framework
2009
The ins and outs of spin: Using the microporous coordination polymer {Fe(pz)[Pt(CN)(4)]} (1, pz=pyrazine), incorporating spin-crossover subunits, two-directional magnetic chemo-switching is achieved at room temperature. In situ magnetic measurements following guest vapor injection show that most guest molecules transform 1 from the low-spin (LS) state to the high-spin (HS) state, whereas CS(2) uniquely causes the reverse HS-to-LS transition.
Electrocatalytic properties of manganese and cobalt polyporphine films toward oxygen reduction reaction
2018
International audience; Novel member of polymetalloporphines, namely manganese polymetalloporphine of type I (pMnP-I) obtained by ion exchange from magnesium polyporphine of type I (pMgP-I) is reported for the first time and compared to its cobalt analogue (pCoP-I). Both polymer films have been obtained via two-step procedure: demetaladon of the pMgP-I electrode film via its exposure to trifluoroacetic acid solution, resulting in formation of the metal-free polyporphine of type I (pH(2)P-I) followed by electrochemically induced incorporation of Co or Mn ions from the acetonitrile solution of cobalt and manganese perchlorates. A further oxidative transformation of pCoP-I, polymer films has l…
Copper( ii ) complexes with phosphorylated 1,10-phenanthrolines: from molecules to infinite supramolecular arrays
2016
International audience; The reaction of phosphorylated 1,10-phenanthrolines 3-Pphen, 3,8-Pphen and 4,7-Pphen (3-Pphen = 3-diethoxyphosphorylphenanthroline, 3,8-Pphen = 3,8-bis(diethoxyphosphoryl) phenanthroline, 4,7-Pphen = 4,7-bis(diethoxyphosphoryl) phenanthroline) and hydrated copper(II) nitrate in a 1 : 1 ratio leads to the formation of supramolecular architectures. In the 1D coordination polymer [Cu(3-Pphen)(NO3)(2)](n) (2) the copper atom is coordinated to only one phenanthroline ligand and the coordination sphere is completed by two oxygen atoms of nitrate anions and the oxygen atom of the phosphoryl group from the neighbouring phenanthroline ligand. Complex Cu(3,8-Pphen)(NO3)(2) (3)…
La préservation de l'environnement nocturne : les enjeux d'une controverse sociotechnique
2013
This communication explains the birth of an environmental problem, light pollution, understood as a socio-technical controversy. Over forty years, in support of the actor-network approach, it traces the conditions of its emergence, transformation and dissemination to local, national and transnational levels, and through various professional disciplines. Schematically, "environmentalists" uphold a holistic approach of "nocturnité" and define artificial light as a pollutant. Facing them, the "technicist" defend a segmented approach and define artificial light as a nuisance. The implementation of this controversy on the political agenda leads to institutional decisions that grasp it with diffi…
Intramolecular 1,5-S...N σ-hole interaction in (E)-N′-(pyridin-4-ylmethylidene)thiophene-2-carbohydrazide
2020
The hydrazide-hydrazone forms inverse dimers via hydrogen bonding, but its conformation is defined by the presence of an intramolecular chalcogen bond. Electrostatic forces dominate in the crystal packing and give rise to a layered supramolecular structure.
A Crystalline 1D Dynamic Covalent Polymer
2022
The synthesis of crystalline one-dimensional polymers provides a fundamental understanding about the structure??? property relationship in polymeric materials and allows the preparation of materials with enhanced thermal, mechanical, and conducting properties. However, the synthesis of crystalline one-dimensional polymers remains a challenge because polymers tend to adopt amorphous or semicrystalline phases. Herein, we report the synthesis of a crystalline one-dimensional polymer in solution by dynamic covalent chemistry. The structure of the polymer has been unambiguously confirmed by microcrystal electron diffraction that together with charge transport studies and theoretical calculations…
Photoactivity and Chemical Reactivity in Titanium(IV)-Organic Frameworks
2020
La presente tesis doctoral ha sido realizada como compendio de publicaciones y lleva por título “Fotoactividad y reactividad química en redes metal-orgánicas de titanio(IV)” (Photoactivity and Chemical Reactivity in Titanium(IV)-Organic Frameworks). La tesis se encuentra dividida en cinco capítulos además de un capítulo final de conclusiones y un resumen en castellano. El primer capítulo trata de una introducción acerca de las redes metal-orgánicas (del inglés Metal-Organic Frameworks, MOFs) de titanio(IV) existentes hasta la fecha para dar una visión general de su variedad estructural, así como de las estrategias sintéticas empleadas y las propiedades fotocatalíticas de estos materiales. E…
Nuevos materiales moleculares de hierro(II) multipropiedad basados en el fenómeno de transición de espín
2017
En esta Tesis Doctoral se presenta la síntesis y caracterización de una serie de materiales multifuncionales de FeII que tienen como denominador común el fenómeno de transición de espín (TS). El objetivo general es investigar sinergias entre la TS y otra propiedad fisicoquímica mediante el estudio de su estructura molecular y sus propiedades magnéticas y calorimétricas, entre otras. En el Capítulo Uno se exponen los conceptos más relevantes del fenómeno TS en el cual los centros TS experimentan una conversión de espín HS↔LS (HS: estado de espín alto, LS: estado de espín bajo) en respuesta a un estímulo externo tal como temperatura, presión, luz o la presencia de analitos. En particular, una…
Exploiting the Potential of New Coordination Frameworks for Technological Applications – from Temperature Sensing to Magnetic Storage
2022
Esta tesis es sobre el diseño, síntesis y caracterización de nuevos Polimeros de Coordinación (CPs), porosos o no, que muestran propiedades magnéticas y/o ópticas, para explotar su potencial en diversas aplicaciones tecnológicas. El diseño de estos materiales requiere una atención particular en la selección de los componentes básicos moleculares, los ligandos orgánicos y los nodos metálicos. Para construir CP con diferentes propiedades físicas, se han elegido derivados de carboxilato y anilato. En particular, el ácido 1,3,5-bencentricarboxílico (H3BTC, ácido trimésico), un ligando bioacompatible que permite construir polimeros organometálicos 3D robustos, y el 3,6-ditriazolil-2,5 -dihidroxi…
Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level
2016
HKUST-1 is a metal-organic framework (MOF) which plays a significant role both in applicative and basic fields of research, thanks to its outstanding properties of adsorption and catalysis but also because it is a reference material for the study of many general properties of MOFs. Its metallic group comprises a pair of Cu2+ ions chelated by four carboxylate bridges, forming a structure known as paddle-wheel unit, which is the heart of the material. However, previous studies have well established that the paddle-wheel is incline to hydrolysis. In fact, the prolonged exposure of the material to moisture promotes the hydrolysis of Cu-O bonds in the paddle-wheels, so breaking the crystalline n…