The novel formation of ordered and varied silica-imidazole complexes from silicic acid

Fixed quantities of silicic acid in isopropyl alcohol were treated with varying amounts of imidazole in the same solvent, left closed till complexation was complete (<SUP>~</SUP>7 days) and the resulting gels on slow evaporation (<SUP>~</SUP>30 days) afforded glassy solids, ranging from nodules to tubules, as seen by scanning electron microscope (SEM). In another strategy where soluble oligomers of silica along with monomers can be present and the reaction conditions remaining the same, rectangular cubes of varying sizes were secured. In the view of the significance and potential utility of this novel finding, only duplicate runs, which essentially afforded similar SEM are included here. Elemental analysis established the presence of imidazole in the complexes and their percentage composition was computed using thermo gravimetric analysis (TGA). FTIR showed organics, presence of hydrogen-bonded imidazole, Si-O-Si bonds, and complete absence of Si-O-C bonds. It is suggested that a pattern where hydrogen-bonded imidazole with itself and the polymer, is entombed in the polymerized silicic acid. Domains having such a profile most likely lead to the observed morphology.The present work vastly widens the scope for silicic acid-guest complexation and holds potential to discover a range of silica harboring materials

Not Available

Not AvailableFixed quantities of silicic acid in isopropyl alcohol were treated with varying amounts of imidazole in the same solvent, left closed till complexation was complete (~7 days) and the resulting gels on slow evaporation (~30 days) afforded glassy solids, ranging from nodules to tubules, as seen by scanning electron microscope (SEM). In another strategy where soluble oligomers of silica along with monomers can be present and the reaction conditions remaining the same, rectangular cubes of varying sizes were secured. In the view of the significance and potential utility of this novel finding, only duplicate runs, which essentially afforded similar SEM are included here. Elemental analysis established the presence of imidazole in the complexes and their percentage composition was computed using thermo gravimetric analysis (TGA). FTIR showed organics, presence of hydrogen-bonded imidazole, Si-O-Si bonds, and complete absence of Si-O-C bonds. It is suggested that a pattern where hydrogen-bonded imidazole with itself and the polymer, is entombed in the polymerized silicic acid. Domains having such a profile most likely lead to the observed morphology.The present work vastly widens the scope for silicic acid—guest complexation and holds potential to discover a range of silica harboring materials.Not Availabl

5-Amino-2-mercapto-1,3,4-thiadiazole: a new matrix for the efficient matrix-assisted laser desorption/ionization of neutral carbohydrates

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Furanoid sugar amino acid based peptidomimetics: well-defined solution conformations to gel-like structures

Furanoid sugar amino acid based peptide and a dimer fold into pseudo &#946;-turn-like structures in DMSO-d6 with intramolecular H-bonds between LeuNH and sugarOH. In CDCl3, they display a repeating &#946;-turn-type secondary structure at lower concentrations and start to form aggregates that gradually turn into excellent organogels as the concentrations are increased, a phenomenon observed for the first time in sugar amino acid containing peptides

Conformational studies of the linear homooligomers of a glucose-derived furanoid sugar amino acid

Conformational analysis of the linear tetramer of the glucose-derived furanoid sugar amino acid 1 by NMR and constrained molecular dynamics studies revealed that the fully protected tetramer 2a has a well-defined structure in CDCl3 with repeating &#946;-turns, each involving a 10-membered ring structure with intramolecular hydrogen bonds between NHi &#8594; C = Oi-2. Its deprotected versions 2b and 2c showed aggregation in organic solvents with structures similar to that of 2a

Development of potassium-selective ion-sensitive field-effect transistor (ISFET) by depositing ionophoric crown ether membrane on the gate dielectric, and its application to the determination of K⁺-ion concentrations in blood serum

112-118This paper reports the fabrication and characterization of potassium ISFET (ion-sensitive field-effect transistor) by deposition of a crown ether layer on the gate. This ISFET is referred to as potassium MEMFET (membrane field-effect transistor) or potassium-selective MEMFET device. Calibration of ISFET in standard KCl solutions has shown that the sensitivity of crown ether-ISFET towards potassium (2.3 mV/mg/L) was approximately double that of the nitride-gate ISFET (1 mV/mg/L) in the 100-400 mg/L range. The mechanism of ISFET potassium sensitivity enhancement by the ionophoric crown ether layer on the gate has been explained. Use of the device for potassium concentration measurements in human blood serum has been demonstrated. The distribution of potassium ion concentrations (151-210 mg/L) in a series of human blood serum samples has been determined from the reference value obtained by atomic absorption spectroscopy and the ISFET sensitivity measured with KCl solutions. These diluted samples showed a constant pH ~ 7.0-7.1, confirming the maintenance of pH within close tolerance by the human body; therefore any errors due to pH variation amongst the samples were eliminated. Sensitivity of the ISFET with/without crown ether coating on the gate towards sodium ions (0.34 mV/mg/L) has been found to be comparatively less than that of the crown ether ISFET for potassium, showing that sodium ions in blood serum do not interfere with the measurements

Synthesis, characterization, ion exchange, and catalytic properties of nanobinary and ternary metal oxy/hydroxides

Nanobinary (Mg-Al) and ternary (Ni-Mg-Al) metal oxy/hydroxides were synthesized by aerogel protocol. The key features of this method are homogenization of metal organic precursors in methanol-toluene mixture, controlled hydrolysis, gelation, hydrothermal treatment, and finally supercritical drying of solvent. The obtained materials, which on further drying at 120 °C, display high surface area, &gt;500 m2 g-1, and smaller particle size, &lt;20 nm. The samples were further characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric and differential thermal analysis (TG-DTA), and solid state 27Al nuclear magnetic resonance (NMR). The ion exchange and catalytic properties of the resulting nanomaterials were compared with hydrotalcite-like layered double hydroxides (LDHs) prepared by a conventional coprecipitation method. The nanoternary system exhibits 2-4-fold increase in activity of pre-reforming of naphtha