Malayanines A and B, two novel limonoids from Chisocheton erythrocarpus Hiern

Two structurally interesting novel limonoids, malayanine A and malayanine B, were isolated from the bark of Chisocheton erythrocarpus Hiern. The structures were fully characterized through spectroscopic methods.     

Mechanochemical reaction of TiO<Subscript>2</Subscript> with β-alanine for the preparation of visible light active nitrogen doped titania: adsorption and kinetic studies

Nitrogen doped TiO₂ (TiO_2−xN_x) with a homogenous anatase phase was synthesized, using β-alanine as a nitrogen precursor and ethanol as a oxygen depriving agent in the concentration range of 0.05, 0.10, 0.15 and 0.2 at% and were characterized by Powder X-ray Diffraction (PXRD), X-ray Photoelectron Spectra (XPS), Scanning Electron Microscope (SEM), Fourier Transform Infrared (FT-IR) and UV–visible Diffused Reflectance Spectroscopic (DRS) techniques. Ethanol deprives the surface oxygen, thereby generating oxygen defects whose concentration was evaluated by FTIR, Photoluminescence (PL) and Electron Spin Resonance (ESR) studies. FTIR analysis reveal that concentration of oxygen vacancies/defects (V_o) decreases as the nitrogen concentration increases leading to the reduction in the Ti–O bond length. This results in a shift of the IR absorption peak towards a low wave number as predicted by simple physical harmonic oscillator model. The Ti 2p_3/2 XPS spectra of TiO_2−xN_x shifts to lower binding energies due to the increase in the electron densities around the Ti atoms indicating the formation of Ti³⁺ in the doped samples. N₂ adsorption–desorption isotherms measurements show a slight increase in the Brunner–Emmet–Teller (BET) surface area, pore diameter, mesopore volume, while the crystallite size and the morphology were also effected by the nitrogen doping. The equilibrium adsorption of Toluene molecules on the photocatalyst surface follows Langmuir theory and the rate controlling step could be the surface reaction of the adsorbed Toluene molecules.     

Solid-state halide ion-selective electrodes: studies of quaternary ammonium halide solutions and determination of surfactants

The feasibility of using homogeneous membrane-type halide ion-selective electrodes in solutions containing cationic surfactant compounds was examined. The results established the applicability of these electrodes for monitoring halide ions in solution without interference by the surfactants. The data also provided a basis for estimation of the surfactant in solution through the halide content. Two typical plating-bath compositions containing CTAB have been successfully analysed for their surfactant content by this procedure.     

Phenanthrene-imidazole-based fluorescent sensor for selective detection of Ag+ and F− ions: real sample application and live cell imaging

Research on Chemical Intermediates - 4-Methyl-2,6-bis(1H-phenanthro[9,10-d]imidazol-2-yl)phenol (probe-MPIP) conjugate has been designed as a selective fluorescent probe for silver (Ag+) ions. The...     

Hexadecyltriethoxysilane-induced Dispersions of Metal Oxide Nanoparticles in Nonpolar Solvents

Nanoparticles of CeO₂, Fe₃O₄, TiO₂ and ZnO get coated by hexadecyltriethoxysilane on refluxing the nanoparticles and the organosilane in a hydrocarbon solvent. The organosilane-coated metal oxide nanoparticles give stable dispersions in hydrocarbon solvents due to their hydrophobic surface. On heating in air, the organosilane-coated metal oxide nanoparticles yield to silica-coated core-shell type nanoparticles. Dedicated to Late Professor F. A. Cotton.     

A simple urea-based route to ternary metal oxynitride nanoparticles

Ternary metal oxynitrides are generally prepared by heating the corresponding metal oxides with ammonia for long durations at high temperatures. In order to find a simple route that avoids use of gaseous ammonia, we have employed urea as the nitriding agent. In this method, ternary metal oxynitrides are obtained by heating the corresponding metal carbonates and transition metal oxides with excess urea. By this route, ternary metal oxynitrides of the formulae MTaO₂N (M=Ca, Sr or Ba), MNbO₂N (M=Sr or Ba), LaTiO₂N and SrMoO_3−xN_x have been prepared successfully. The oxynitrides so obtained were generally in the form of nanoparticles, and were characterized by various physical techniques.     

Structural characterization of Th-doped TiO2 photocatalyst and its extension of response to solar light for photocatalytic oxidation of oryzalin pesticide: a comparative study

The degradation efficiency of Th-doped TiO₂ / TiO₂ photocatalysts were investigated under UV and solar light illumination. The model compound chosen for the study was Oryzalin (OZ). Doping of inner transition metal ion Th was intended to modify the electronic properties of TiO₂. The Th-doped TiO₂ were synthesized by incorporating 0.02, 0.04, 0.06, and 0.1 atom percentage of Th into the TiO₂ lattice by solid-state reaction. The stochiometry of the prepared samples is Ti_1−xTh_xO₂, where ‘x’ is the percentage of Th. The samples were characterized by UV-Visible absorption, UV-Visible -Diffused reflectance spectra, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and X-ray Diffraction (XRD). The pore size and surface area of these samples were studied by Brunauer, Emmett and Teller (BET) adsorption method. It was found that metal ion doping at various percentage compositions enables a large shift in the absorption band of the TiO₂ towards visible light region. This is due to the formation of various mid band gaps at 2.84 eV, 2.804 eV, 2.66 eV, and 2.55 eV. The extent of degradation of the pesticide was followed by UV-Visible spectroscopy and GC-MS methods. Based on the spectral analysis, the probable degradation reaction mechanism for OZ is proposed. These results indicate that Th-doped TiO₂ with the modified electronic properties is a good catalyst under solar light irradiation. But these particles show marginal variation in rates under UV-illumination. All the photodegradation reactions follow the first order kinetics.      

Nanoparticles of superconducting γ-Mo2N and δ-MoN

We have been able to prepare nanoparticles (∼4 nm diameter) of cubic γ-Mo₂N by a simple procedure involving the reaction of MoCl₅ with urea at 873 K. The nanoparticles show a superconducting transition around 6.5 K. The γ-Mo₂N nanoparticles are readily transformed to nanoparticles of δ-MoN with a slightly larger diameter on heating in a NH₃ atmosphere at 573 K. Phase-pure δ-MoN obtained by this means shows a superconducting transition around 5 K.     

Sol-gel based surface modification of electrodes for electro analysis

In chemical analysis and electrochemical catalysis modified electrodes have been used in a wide range. In addition to the several methods of electrode modification reported in literature, the sol-gel route offers a possibility of preparing ceramic like films under rather mild conditions. This enhances the possibility of incorporation of temperature sensitive particles such as enzymes, microorganisms, proteins and several other biomolecules into such composite layers, resulting in very inert and stable matrices useful for analytical applications. The present paper, in addition to providing an overview of the various analytical applications of sol-gel processes, presents the fabrication and evaluation, of a novel sol-gel based potentiometric sensor for pH measurement. The performance characteristics of the sol-gel based pH sensor is evaluated using buffers in the pH range 2-10 prepared using standard buffer compositions reported in literature. The results show a linear correlation between negative logarithm of hydrogen ion concentration and measured millivolt response.     

Synthesis and NMR spectral study of some t(3)-aryl-r(2),c(4)-bisethoxycarbonyl-t(5)-hydroxy-c(5)-methylcyclohexanones

Six t(3)-aryl-r(2),c(4)-bisethoxycarbonyl-t(5)-hydroxy-c(5)-methylcyclohexanones (6-11) were synthesized by condensing ArCHO (Ar = Ph, p-O(2)NC(6)H(4), p-CH(3)OC(6)H(4), p-ClC(6)H(4), m-O(2)NC(6)H(4) and m-C(6)H(5)O(6)H(4)) with ethyl acetoacetate in the presence of methylamine and their (1)H and (13)C NMR spectra were recorded. (1)H-(1)H COSY and NOESY spectra were recorded for 6 and 7 and also HSQC and HMBC spectra for 6 and 8. Elemental analysis was carried out for all compounds. The mass spectrum was recorded for 8. All analytical data are consistent with the proposed molecular formulae. Analysis of NMR spectral data suggests that these compounds largely adopt chair conformations with the hydroxyl group occupying an axial orientation and all the other substituents occupying equatorial orientations. Long-range coupling (2-3 Hz) between the OH proton and the axial methylene proton at C-6 is observed in 6, 7, 8 and 11.