ABSTRACT
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ABSTRACT
Topological transitions between considerably different phases typically require harsh conditions to collectively break chemical bonds and overcome the stress caused to the original structure by altering its correlated bond environment. In this work we present a case system that can achieve rapid rearrangement of the whole lattice of a metal-organic framework through a domino alteration of the bond connectivity under mild conditions. The system transforms from a disordered metal-organic framework with low porosity to a highly porous and crystalline isomer within 40 s following activation (solvent exchange and desolvation), resulting in a substantial increase in surface area from 725 to 2,749 m2 g-1. Spectroscopic measurements show that this counter-intuitive lattice rearrangement involves a metastable intermediate that results from solvent removal on coordinatively unsaturated metal sites. This disordered-crystalline switch between two topological distinct metal-organic frameworks is shown to be reversible over four cycles through activation and reimmersion in polar solvents.
ABSTRACT
In searching for practical crystalline porous solids, two unique hybrid materials with featured functions, In-bpy and In-dpe, were prepared without deliberately designed organic linker units or complex post-modification procedures. Composed of oxalate-embedded metal phosphite (MPO) sheets and bipyridyl-type ligands of varied molecular lengths, they show a common pillar-layered topology but are the first well-characterized organo-MPOs to possess genuine porosity, substantiated by CO2 adsorption, and structural stability under harsh conditions. In-bpy exhibits a turn-on fluorescence signal when in contact with p-xylene, making it the first MPO-based sensing material with selectivity and recyclability. Furthermore, In-dpe demonstrates a facile and unprecedented route to the superhydrophobicity of porous solids via a [2+2] photocycloaddition reaction between linker and foreign units. Our findings suggest that MPO may serve as a promising platform for hybrid frameworks to create many more functional porous materials.
ABSTRACT
In our novel green approach, the waste polyethylene terephthalate (PET) bottle material has effectively been used as the starting precursor instead of terephthalic acid for the synthesis of five terephthalate based nanoporous trivalent metal-organic frameworks (MOFs) namely MIL-47, MIL-53(Cr), MIL-53(Al), MIL-53(Ga), and MIL-101(Cr). The optimum reaction parameters to achieve the green synthesis were studied. These MOFs were structurally identified by using powder X-ray diffraction (PXRD) measurements. Scanning electron microscopy (SEM) images confirm the particle nature and size of the synthesized MOFs. Nitrogen gas sorption measurements have been done for some of the MOFs to check their porous properties. All the characterization techniques strongly supported that the synthesized MOFs using PET are similar to their literature reports. The gas adsorption studies for the synthesized MIL-53(Cr) and MIL-101(Cr) showed their significant gas uptake capability towards CO2 and H2 gases. Further, the synthesized MIL-47 and MIL-101(Cr) have been tested for their catalytic ability in chemical fixation of CO2 gas through the conversion of CO2 and epoxides to the corresponding cyclic carbonates which shows promising results to use them as catalysts.
ABSTRACT
A simple nanoporous metal organic framework (MOF) bioreactor preparation via a low energy 30 minute vortex as driving force to immobilize trypsin enzyme is presented. No chemical modifications were employed thus organic wastes were eliminated. The digestion efficiency of this trypsin bioreactor is exceptionally high, even when reused. This "green" synthesis procedure produced a "green" bioreactor.
ABSTRACT
The crystal structure of the title complex, [Ni(C(7)H(4)NO(4))(2)(C(10)H(8)N(2))(2)](n), exhibits a two-dimensional network, which is built up from slightly distorted NiN(4)O(2) polyhedra (2 symmetry), bipyridine ligands, and carboxyl-ate anions. The Ni(II) atoms are six-coordinated by two O atoms of two monodentate carboxyl-ate anions and four N atoms from bipyridine ligands and are connected into layers by the 4,4'-bipyridine ligands.
