Effect of nickel doping on structural, optical and electrical properties of TiO2 nanoparticles by sol-gel method

Nickel-doped anatase TiO₂ nanoparticles have been prepared by sol-gel method. The X-ray powder diffraction study reveals that all the prepared samples have pure anatase phase tetragonal system. The average crystallite size of the prepared sample is 14 nm, when found through transmission electron microscope. A strong frequency dependence of both dielectric constant (?′) and dielectric loss (tan δ) were observed for various dopant levels at room temperature in the frequency range of 42 Hz to 5 MHz. At low frequency, the piling up of mobile charge carriers at the grain boundary produces interfacial polarization giving rise to high dielectric constant. The asymmetric shape of frequency dependence of the dielectric loss for the primary relaxation process is observed for each concentration. From the ac conductivity studies, the reduction in conductivity may arise due to the decreasing particle with the increase in Ni-dopant level.     

Kinetics of oxidative deamination of some amino acids by diperiodatoargentate(III) in alkaline medium

Kinetics of oxidation of some amino acids, viz. glycine, alanine, valine, leucine, phenylglycine and phenylalanine by diperiodatoargentate(III) have been investigated in alkaline medium. The order of the reaction is found to be one with respect to each reactant. The reaction rates are inversely dependent on both [OH^–] and [periodate]. The oxidation products are found to be ammonia and the corresponding keto acids. The presence of electron-withdrawing groups at the -carbon increases the rate of oxidation while the rate decreases with increasing alkyl chain length. A two-electron-transfer mechanism is proposed to explain the results.

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Crystalline inclusion compounds of tetrabenzo-18-crown-6 with uncharged organic molecules. Solid-state structure of the nitroethane complex

Diethylaminoethyl (DEAE) groups were introduced into -cyclodextrin (-CD) and -CD. The products, DEAE-CDs with various numbers of substituents, trappedp-nitrophenoxide and 3,4-dinitrophenoxide preferentially over their respective conjugate acids. This caused a decreased pK _a of the guest nitrophenol. Some signals of the proton-NMR of both guest nitrophenol and host DEAE-CD changed upon host-guest interaction. The relation between the number of DEAE groups and the extent of the pK _a decrease, as well as association constants, is discussed.     

Electronic structure and high pressure phase transition in LaSb and CeSb

The electronic structure and high pressure structural phase transition in lanthanum and cerium antimonides have been investigated using the tight binding LMTO method. Calculation of the total energy reveals that the simple tetragonal structure is stable at high pressure for both the compounds. In LaSb, the calculated values of the equilibrium cell volume and the cell volume at which phase transition occurs agree with the experimental results. However, in CeSb, the agreement is not so good. We have also predicted the most favouredc/a value in the simple tetragonal phase for these compounds. Further, we present the calculated results on the electronic structure of these systems at the equilibrium as well the reduced cell volumes.     

Growth of zinc oxide nanostructures

Zinc oxide (ZnO) nanowhiskers have been prepared using a multilayer ZnO(50 nm)/Zn(20 nm)/ZnO(2μm) structure on a polished stainless steel (SS) substrate by high rate magnetron sputtering. The formation of uniformly distributed ZnO nanowhiskers with about 20 nm dia. and 2 to 5 μm length was observed after a postdeposition annealing of the prepared structure at 300–400° C. An array of highlyc-axis oriented ZnO columns (70–300 nm in dia. and up to 10 μm long) were grown on Si substrates by pulsed laser deposition (PLD) at a high pressure (1 Torr), and Raman studies showed the activation of surface phonon modes. The nanosized powder (15–20 nm) and nanoparticle ZnO films on glass substrate were also prepared by a chemical route. Nanowhiskers showed enhanced UV light detection characteristics, and the chemically prepared ZnO nanoparticle films exhibited good sensing properties for alcohol     

Hydrophobicity induced vapor-phase oxidation of propene over gold supported on titanium incorporated hybrid mesoporous silsesquioxane

Gold nanoparticles supported on highly hydrophobic ethane bridged Ti incorporated mesoporous organosilica are reported for enhanced vapor phase epoxidation of propene using H2 and O2.     

Copper-catalyzed one-pot process to construct triazole-linked urea derivatives

A new one-pot synthetic methodology has been developed to construct the triazole-linked urea derivatives. In the same step, triazole forms from azide and alkyne via click reaction and urea forms from addition reaction of amines and isocyanates. The notable features of this work include wide substrate scope, atom economy, environmental friendliness, and easily accessible starting materials. The preliminary biological screening of synthesized compounds show promising cytotoxic activity in basal cell carcinoma (BCC) cell lines.