Search results for "Metal-Organic Framework"
showing 10 items of 194 documents
MMX Chains and Molecular Species Containing Rh 2 n+ ( n = 4, 5, and 6) Units: Electrical Conductivity in Crystal Phase of MMX Polymers
2010
The control of the experimental conditions in the reaction of Rh 2 (O 2 CCH 3 ) 4 with halides allows the isolation of the novel dirhodium complexes K x [Rh 2 X(O 2 CCH 3 ) 4 ] x ·4xH 2 O (X = Br, 1·4H 2 O and I, 2·4H 2 O) [Rh 2 (O 2 CCH 3 ) 4 Cl] x H 2 O (3·H 2 O), [Rh 2 (O 2 CCH 3 )Cl] x ·4xH 2 O (3·4H 2 O), and {Rh 2 (O 2 CCH 3 ) 4 I 2 ]· 4H 2 0 (4·4H 2 O) containing Rh 2 n+ (n = 4, 5 and 6) units. The X-ray structure determination of compounds 1-4 reveals the presence of dirhodium units in different oxidation states. The polyanionic complexes 1·4H 2 O and 2·4H 2 O containing Rh 2 4+ units give zig-zag chains. In contrast, the partially oxidized complexes 3·H 2 O and 3·4H 2 O containing …
Metal-organic frameworks conjugated with biomolecules as efficient platforms for development of biosensors
2021
Abstract Recent developments in the field of metal-organic frameworks (MOFs) have renewed the interests of scientists to bring about a major breakthrough in this field soon. These particles consist of ultra-highly porous and tremendous internal surface areas with extraordinary variabilities that make them highly potent compounds in nanomedicine. Moreover, low weight, large free volumes, and multiple functionalities of these particles have made them extremely attractive for various applications. Along with a critical role in the adsorption and separation of different analytes, they also have an immense role in the development of biosensor platforms that are expected to pave the way for accur…
Cooperative High-Temperature Spin Crossover Accompanied by a Highly Anisotropic Structural Distortion
2016
Spin transitions are a spectacular example of molecular switching that can provoke extreme electronic and structural reorganizations in coordination compounds. A new 3D cyanoheterometallic framework, [Fe(pz)(Au(CN)2)2], has been synthesized in which a highly cooperative spin crossover has been observed at 367 and 349 K in heating and cooling modes, respectively. Mössbauer spectroscopy revealed a complete transition between the diamagnetic and paramagnetic states of the iron centres. The low-spin-to-high-spin transition induced a drastic structural distortion involving a large one-directional expansion (ca. 10.6%) and contraction (ca. 9.6%) of the lattice. Negative thermal expansion along th…
Effect of t-BuS vs. n-BuS on the topology, Cu⋯Cu distances and luminescence properties of 2D Cu4I4/RS(CH2)4SR metal–organic frameworks
2011
CuI reacts with RS(CH2)4SR (R = n-Bu (L1); t-Bu (L2)) to afford the 2D coordination polymers [Cu4I4{μ-RS(CH2)4SR}2]n (R = n-Bu (1); t-Bu (2)). Their grid networks exhibit nodal Cu4(μ3-I)4 clusters interconnected by dithioethers with mean Cu⋯Cu distances of 2.7265(10) and 2.911(2) A for 1 and 2, respectively. This difference translates in a blue shift of the solid state emission bands and a decrease in emission lifetimes when trading R = n-Bu to the bulky t-Bu.
Direct Visualization of Pyrrole Reactivity upon Confinement within a Cyclodextrin Metal–Organic Framework
2019
Metal–organic frameworks can be used as porous templates to exert control over polymerization reactions. Shown here are the possibilities offered by these crystalline, porous nanoreactors to capture highly-reactive intermediates for a better understanding of the mechanism of polymerization reactions. By using a cyclodextrin framework the polymerization of pyrrole is restricted, capturing the formation of terpyrrole cationic intermediates. Single-crystal X-ray diffraction is used to provide definite information on the supramolecular interactions that induce the formation and stabilization of a conductive array of cationic complexes.
Peptide metal-organic frameworks under pressure: flexible linkers for cooperative compression
2018
We investigate the structural response of a dense peptide metal-organic framework using in situ powder and single-crystal X-ray diffraction under high-pressures. Crystals of Zn(GlyTyr)2 show a reversible compression by 13% in volume at 4 GPa that is facilitated by the ability of the peptidic linker to act as a flexible string for a cooperative response of the structure to strain. This structural transformation is controlled by changes to the conformation of the peptide, which enables a bond rearrangement in the coordination sphere of the metal and changes to the strength and directionality of the supramolecular interactions specific to the side chain groups in the dipeptide sequence. Compar…
Selective CO 2 Sorption Using Compartmentalized Coordination Polymers with Discrete Voids**
2021
Carbon capture and storage with porous materials is one of the most promising technologies to minimize CO2 release into the atmosphere. Here, we report a family of compartmentalized coordination polymers (CCPs) capable of capturing gas molecules in a selective manner based on two novel tetrazole-based ligands. Crystal structures have been modelled theoretically under the Density Functional Theory (DFT) revealing the presence of discrete voids of 380 A3 . Single gas adsorption isotherms of N2 , CH4 and CO2 have been measured, obtaining a loading capacity of 0.6, 1.7 and 2.2 molecules/void at 10 bar and at 298 K for the best performing material. Moreover, they present excellent selectivity an…
Interpenetrated Luminescent Metal-Organic Frameworks based on 1H-Indazole-5-carboxylic Acid
2020
Herein we report the formation and characterization of two novel Zn-based multifunctional metal-organic frameworks (MOFs) based on 1H-indazole-5-carboxylic acid and bipyridine-like linkers, synthesized by soft solvothermal routes. These materials possess isoreticular 2-fold interpenetrated three-dimensional structures that afford a flexible character and allow porosity modulation of the MOFs as confirmed by CO2 sorption measurements. Apart from this attractive structural feature, the MOFs exhibit fascinating luminescent properties involving both luminescence thermometry and long-lasting phosphorescence.
A series of lanthanide(iii) metal-organic frameworks derived from a pyridyl-dicarboxylate ligand: single-molecule magnet behaviour and luminescence p…
2020
The reactions of LnIII ions with a versatile pyridyl-decorated dicarboxylic acid ligand lead to the formation of a series of novel three-dimensional (3D) Ln-MOFs, [Ln3(pta)4(Hpta)(H2O)]·xH2O (Ln = Dy (1), Eu (2), Gd (3), Tb (4), H2pta = 2-(4-pyridyl)-terephthalic acid, x = 6 for 1, 2.5 for 2, 1.5 for 3 and 2 for 4). The Ln3+ ions act as nine-coordinated muffin spheres, linking to each other to generate trinuclear {Ln3(OOC)6N2} SBUs, which are further extended to be interesting 3D topological architectures. To the best of our knowledge, the Dy-MOF exhibits zero-field single-molecule magnet (SMM) behaviour with the largest effective energy barrier among the previously reported 3D MOF-based Dy…
Bicyclo[2.2.2]octane-1,4-dicarboxylic acid: towards transparent metal–organic frameworks
2017
The preparation of transparent porous materials can offer a different access towards the study of molecules under solid confined space. Metal-organic frameworks represent a unique opportunity due to their tunable pore size, however aromatic linkers present strong absorption and reduce the transparency. Herein, we report the first example of a MOF with bicyclic organic dicarboxylic linkers and its use as a solid solvent.