A series of five thermally and chemically stable functionalized covalent organic frameworks (COFs), namely, TpPa-NO2, TpPa-F4, TpBD-(NO2)2, TpBD-Me2, and TpBD-(OMe)2 were synthesized by employing the solvothermal aldehyde-amine Schiff base condensation reaction. In order to complete the series, previously reported TpPa-1, TpPa-2, and TpBD have also been synthesized, and altogether, eight COFs were fully characterized through powder X-ray diffraction (PXRD), Fourier transform IR (FT-IR) spectroscopy, (13)C solid-state NMR spectroscopy, and thermogravimetric analysis. These COFs are crystalline, permanently porous, and stable in boiling water, acid (9 N HCl), and base (3 N NaOH). The synthesized COFs (all eight) were successfully delaminated using a simple, safe, and environmentally friendly mechanical grinding route to transform into covalent organic nanosheets (CONs) and were well characterized via transmission electron microscopy and atomic force microscopy. Further PXRD and FT-IR analyses confirm that these CONs retain their structural integrity throughout the delamination process and also remain stable in aqueous, acidic, and basic media like the parent COFs. These exfoliated CONs have graphene-like layered morphology (delaminated layers), unlike the COFs from which they were synthesized.
Two new chemically stable functional crystalline covalent organic frameworkds (COFs) (Tp-Azo and Tp-Stb) were synthesized using the Schiff base reaction between triformylphloroglucinol (Tp) and 4,4'-azodianiline (Azo) or 4,4'-diaminostilbene (Stb), respectively. Both COFs show the expected keto-enamine form, and high stability toward boiling water, strong acidic, and basic media. H3PO4 doping in Tp-Azo leads to immobilization of the acid within the porous framework, which facilitates proton conduction in both the hydrous (σ = 9.9 × 10(-4) S cm(-1)) and anhydrous state (σ = 6.7 × 10(-5) S cm(-1)). This report constitutes the first emergence of COFs as proton conducting materials.
A single phase molecular adduct, MgCl2·6CH3OH has been synthesized using MgCl2 and the simplest
alcohol, methanol. Structural, spectroscopic, and morphological studies
have been carried out for a better understanding of the single phase
MgCl2·6CH3OH adduct. 13C CPMAS
solid state NMR studies show all six methanol molecules are magnetically
equivalent and present in a single environment around the Mg2+ center. Raman spectral analysis of the characteristic peak at 708
cm–1 substantiates octahedral coordination of six
CH3OH molecules around Mg2+. Solid state 13C NMR measurements, made after heat treatment at different
temperatures, have been utilized to understand the variations in CH3OH stoichiometry and coordination around Mg2+ with
temperature. A titanated active catalyst, TiCl4 on MgCl2·6CH3OH, has also been synthesized and subjected
to detailed characterizations. The active catalyst shows high surface
area (102 m2/g) and mesoporosity. The titanated catalyst
has been screened for ethylene polymerization reactions using different
cocatalysts (R3Al; R= −CH3, −CH2CH3, and −CH2CH(CH3)2). A total of 7.25 kg of polyethylene per gram of catalyst
has been obtained with Me3Al cocatalyst, which is six times
higher in activity compared with commercial Me3Al/TiCl4/ MgCl2·6EtOH-supported catalyst. Although
porosity influences the catalytic activity, other factors also seem
to contribute to the total catalytic activity.
SummaryMolecular changes elicited by plants in response to fungal attack and how this affects plant–pathogen interaction, including susceptibility or resistance, remain elusive. We studied the dynamics in root metabolism during compatible and incompatible interactions between chickpea and Fusarium oxysporum f. sp. ciceri (Foc), using quantitative label‐free proteomics and NMR‐based metabolomics. Results demonstrated differential expression of proteins and metabolites upon Foc inoculations in the resistant plants compared with the susceptible ones. Additionally, expression analysis of candidate genes supported the proteomic and metabolic variations in the chickpea roots upon Foc inoculation. In particular, we found that the resistant plants revealed significant increase in the carbon and nitrogen metabolism; generation of reactive oxygen species (ROS), lignification and phytoalexins. The levels of some of the pathogenesis‐related proteins were significantly higher upon Foc inoculation in the resistant plant. Interestingly, results also exhibited the crucial role of altered Yang cycle, which contributed in different methylation reactions and unfolded protein response in the chickpea roots against Foc. Overall, the observed modulations in the metabolic flux as outcome of several orchestrated molecular events are determinant of plant's role in chickpea–Foc interactions.
The crystallization kinetics of template free ultra-small FAU-type zeolite (X) in highly alkaline viscous precursor suspensions is investigated. We focus on understanding the crystallization pathway from an ionic liquid into...
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