Search results for "IC framework"
showing 10 items of 268 documents
All-cis-1,2,3,4,5,6-cyclohexanehexacarboxylate two-dimensional gadolinium(III) complexes: Synthesis, X-ray crystal structure and magnetic properties
2010
Abstract The first gadolinium(III) complexes with the trideprotonated form of the 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H3clhex3−) of formulae [Gd(H3clhex)(H2O)4]n·3nH2O (1) and [Gd(H3clhex)(H2O)4]n·6nH2O (2) have been prepared through the gel technique and their structures determined by single crystal X-ray diffraction. The structure of 1 is made up of 63 honey-comb layers which are generated by [Gd(H2O)4]3+ cations and H3clhex3− anions acting as three-fold nodes and three-fold connectors, respectively. The structure of 2 consists of a [44,62] two-dimensional network extended in the ac plane where the H3clhex−3 groups act as four-fold connectors and the [Gd(H2O)4]3+ units as four-fol…
Integrability Conditions: Recent Results in the Theory of Integrable Models
1990
This paper reports various results achieved recently in the theory of integrable models. These are summarised in the Fig.1! At the Chester meeting [1] two of the authors were concerned [1] with the local Riemann-Hilbert problem (double-lined box in the centre of Fig.1), its limit as a non-local Riemann-Hilbert problem used to solve classical integrable models in 2+1 dimensions (two space and one time dimensions) [2,3], and the connection of this Riemann-Hilbert problem with Ueno’s [4] Riemann-Hilbert problem associated with the representation of the algebra gl(∞) in terms of Z⊗Z matrices (Z the integers) and the solution of the K-P equations in 2+1. We were also concerned [1] with the const…
Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels
2019
Abstract Photon upconversion has enjoyed increased interest in the last years due to its high potential for solar‐energy harvesting and bioimaging. A challenge for triplet–triplet annihilation upconversion (TTA‐UC) processes is to realize these features in solid materials without undesired phase segregation and detrimental dye aggregation. To achieve this, we combine a palladium porphyrin sensitizer and a 9,10‐diphenylanthracene annihilator within a crystalline mesoporous metal–organic framework using an inverted design. In this modular TTA system, the framework walls constitute the fixed sensitizer, while caprylic acid coats the channels providing a solventlike environment for the mobile a…
Breathing-Dependent Redox Activity in a Tetrathiafulvalene-Based Metal–Organic Framework
2018
"Breathing" metal-organic frameworks (MOFs) that involve changes in their structural and physical properties upon an external stimulus are an interesting class of crystalline materials due to their range of potential applications including chemical sensors. The addition of redox activity opens up a new pathway for multifunctional "breathing" frameworks. Herein, we report the continuous breathing behavior of a tetrathiafulvalene (TTF)-based MOF, namely MUV-2, showing a reversible swelling (up to ca. 40% of the volume cell) upon solvent adsorption. Importantly, the planarity of the TTF linkers is influenced by the breathing behavior of the MOF, directly impacting on its electrochemical proper…
Present and Perspectives of Photoactive Porous Composites Based on Semiconductor Nanocrystals and Metal-Organic Frameworks
2021
This review focuses on the recent developments in synthesis, properties, and applications of a relatively new family of photoactive porous composites, integrated by metal halide perovskite (MHP) nanocrystals and metal-organic frameworks (MOFs). The synergy between the two systems has led to materials (MHP@MOF composites) with new functionalities along with improved properties and phase stability, thus broadening their applications in multiple areas of research such as sensing, light-harvesting solar cells, light-emitting device technology, encryption, and photocatalysis. The state of the art, recent progress, and most promising routes for future research on these photoactive porous composit…
Coordination networks incorporating halogen-bond donor sites and azobenzene groups
2016
Two Zn coordination networks, {[Zn(1)(Py)2]2(2-propanol)}n (3) and {[Zn(1)2(Bipy)2](DMF)2}n (4), incorporating halogen-bond (XB) donor sites and azobenzene groups have been synthesized and fully characterized. Obtaining 3 and 4 confirms that it is possible to use a ligand wherein its coordination bond acceptor sites and XB donor sites are on the same molecular scaffold (i.e., an aromatic ring) without interfering with each other. We demonstrate that XBs play a fundamental role in the architectures and properties of the obtained coordination networks. In 3, XBs promote the formation of 2D supramolecular layers, which, by overlapping each other, allow the incorporation of 2-propanol as a gues…
Enantiospecific Response in Cross-Polarization Solid-State Nuclear Magnetic Resonance of Optically Active Metal Organic Frameworks.
2020
We report herein on a NMR-based enantiospecific response for a family of optically active metal-organic frameworks. Cross-polarization of the 1H-13C couple was performed, and the intensities of the 13C nuclei NMR signals were measured to be different for the two enantiomers. In a direct-pulse experiment, which prevents cross-polarization, the intensity difference of the 13C NMR signals of the two nanostructured enantiomers vanished. This result is due to changes of the nuclear spin relaxation times due to the electron spin spatial asymmetry induced by chemical bond polarization involving a chiral center. These experiments put forward on firm ground that the chiral-induced spin selectivity e…
Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule
2014
[EN] A hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl-LDH ferromagnetic layers intercalated with thermoresponsive 4-(4-anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In…
Relativistic corrections and unitary equivalence in elastic electron deuteron scattering.
1993
The role of unitary equivalence of relativistic corrections in elastic electron deutron scattering is studied, starting from a class of approximately, unitarily equivalent Hamiltonians and using consistent charge density operators. The connection of various formal approaches for deriving the relativistic corrections to wave functions and operators are discussed in detail. For reasons of simplicity, we have chosen a pure one-pion-exchange model and calculated the charge and quadrupole form factors of the deuteron. The numerical results show that the unitary equivalence holds at small momentum transfers, but breaks down rather soon with increasing momentum transfers (\ensuremath{\lesssim}5 ${…
Positive effect of the fluorine moiety on the oxygen storage capacity of UiO-66 metal–organic frameworks
2016
Two series of fluorine-containing UiO-66 have been synthesized, replacing the 1,4-benzodicarboxylic acid linker with increasing amounts of 2-fluoro-1,4-benzodicarboxylic acid or 2-trifluoromethyl-1,4-benzodicarboxylic acid. The capacity to store oxygen and nitrogen within these MOFs has been tested, which revealed a positive correlation between the fluorine content and the oxygen storage performances.