Raman and ESR study of sol–gel materials from ZnO–TiO2–B2O3 system

The paper studies the materials from ZnO–TiO₂–B₂O₃ ternary system, obtained by sol–gel method [1] and [2], starting from organic and inorganic precursors. The obtained samples are investigated by FTIR and Raman spectroscopy, which provide structural information, at molecular level. FTIR absorption maxima are identified and discussed according to literature data. Raman spectra are acquired by a Raman Jasco NRS-3100 spectrometer, at 532 nm wavelength and put in evidence characteristic vibration modes for all three oxide components. ESR spectra were plotted with the aid of a JES-FA 100-JEOL Japan spectrometer and titanium surrounding is investigated.     

Catalytic Synthesis of 5‐Substituted Tetrazoles: Unexpected Reactions and Products

Tetrazoles are incredibly useful organic molecules with a wide range of applications from medicinal chemistry as carboxylic acid isosteres to high energy density materials in space research. In an effort to develop an easy protocol for the synthesis of tetrazoles from nitriles, we used nano‐Ag‐TiO₂ as an efficient heterogeneous catalyst for the reaction of various nitriles and sodium azide to afford 5‐substituted tetrazoles in excellent yields. By this method, a wide variety of aryl nitriles underwent [3 + 2] cycloaddition to afford tetrazoles in excellent yields. Further reaction of tetrazoles with ethylchloroacetate resulted in the formation of expected products, except for a bis‐tetrazole, which underwent ring opening and subsequent reaction to afford an unusual product. The bis‐tetrazole also formed an unusual polymeric sodium complex in aq. NaOH solution. X‐ray crystallography revealed a distorted octahedral geometry for the complex, which forms a three‐dimensional network of chains interlinked by bis‐tetrazole moieties through a network of H‐bonds.     

Synthesis of β‐Arylacyl/β‐Heteroarylacyl‐β‐alkylidene Malonates and Their Application in Substituted Pyridone Synthesis

A novel approach has been developed for the synthesis of β‐arylacyl/β‐heteroarylacyl‐β‐alkylidine malonates in moderate to good yields by the reaction of Stork aryl and heteroaryl enamine with β‐chloroalkylidene malonates. The reaction involves conjugate (Michael) addition of Stork enamine on β‐chloroalkylidene malonates and elimination of chloride ion. These Michael adducts were utilized as intermediates for the synthesis of highly substituted 1,4‐dialkyl‐2‐oxo‐6‐aryl/hetreoaryl‐1,2‐dihydro‐pyridine‐3‐carboxylic acid ethyl esters via 5 + 1 ring annulation protocol.     

Bioleaching of Fly Ash by the Tropical Marine Yeast, Yarrowia lipolytica NCIM 3589

Fly ash collected from an Indian thermal power plant was characterised by scanning electron microscope (SEM)-energy dispersive spectrometer, X-ray diffraction and energy dispersive X-ray fluorescence analysis. The effect of fly ash on the growth and morphology of a metal-tolerant tropical marine yeast, Yarrowia lipolytica NCIM 3589, was studied. The growth of the yeast was unaffected by the presence 0.1, 0.2 or 0.3?% fly ash although the surface-to-volume ratio decreased. The yeast formed biofilms on immobilized fly ash as evidenced by SEM observations. The organism produced citric acid and additional extracellular proteins in the presence of fly ash. Leaching of metals from fly ash by Y. lipolytica was compared with chemical leaching by citric acid. Yeast cells were most effective in leaching Cu (59.41?%) although other metals (Zn, Ni, Cu and Cr) were also extracted. Transmission electron microscope images showed the deposition of metals at the cell wall, cell membrane and in the cytoplasm. This paper thus reports a potential application of Y. lipolytica for removal of different metals from solid waste material (fly ash).     

Inhibition of histamine mediated responses by Mirabilis jalapa: confirming traditional claims made about antiallergic and antiasthmatic activity

The roots of Mirabilis jalapa are used traditionally in allergic skin disorders and asthma. The effect of an ethanol:acetone (1:1) extract of the roots of M. jalapa was studied for antihistaminic activity using a guinea pig tracheal chain preparation and clonidine-induced mast cell granulation in mice. Its antiallergic activity was evaluated using milk-induced eosinophilia and albumin-induced paw oedema in mice. The extract (0.5 mL of 100 mg mL(-1)) inhibited histamine-induced guinea pig tracheal chain contractions non-competitively. The extract (100 or 200 mg kg(-1) i.p.) inhibited milk-induced eosinophilia, albumin-induced paw oedema and protected mast cells against clonidine-induced granulation. The study justified the folkloric use of M. jalapa in the treatment of allergic diseases and asthma.     

Structural,optical, and electrical properties of electron beam evaporated CdSe thin films

CdSe films have been deposited on glass substrates at different substrate temperatures between room temperature and 300 °C. The films exhibited hexagonal structure with preferential orientation in the (002) direction. The crystallinity improved and the grain size increased with temperature. Band gap values are found decreasing from about 1.92 eV to 1.77 eV with increase of the substrate temperature. It is observed that the resistivity decreases continuously with temperature. Laser Raman studies show the presence of 2 LO and 3 LO peaks at 416 cm^‐1 and 625 cm^‐1respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

One-step hydrothermal synthesis of marigold flower-like nanostructured MoS<Subscript>2</Subscript> as a counter electrode for dye-sensitized solar cells

MoS₂ thin films with marigold flower-like nanostructures were grown on conductive fluorine-doped tin oxide (FTO) substrates through a one-step hydrothermal synthesis for their application as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Different MoS₂ thin film samples (A–D) were grown on FTO slides using different concentrations of precursors (sodium molybdate and thioacetamide), while keeping the Mo/S molar ratio constant (1:4.6), in all samples. The effect of varying precursor concentrations (3.2–12.6 mM on MoS₂ basis) on the structure of the nanostructured thin films and their performance as DSSC-CEs was investigated. Scanning electron microscopy revealed a material with an infolded petal-like morphology. With increasing precursor concentration, the petal-like structures tended to form bunched nanostructures (100–300 nm) resembling marigold flowers. X-ray diffraction analysis, X-ray photoelectron, and Raman spectroscopy studies showed that the thin films were composed of hexagonal MoS₂ with good crystallinity. Hall effect measurements revealed MoS₂ to be a p-type semiconductor with a carrier mobility of 219.80 cm² V^?1 s^?1 at room temperature. The electrochemical properties of the thin films were examined using cyclic voltammetry and electrochemical impedance spectroscopy. The marigold flower-like MoS₂ thin films showed excellent electrocatalytic activity towards the I¯/I₃¯ reaction and low charge transfer resistance (R_ct) values of 14.77 Ω cm^?1, which was close to that of Pt electrode (12.30 Ω cm^?1). The maximum power conversion efficiency obtained with MoS₂ CE-based DSSCs was 6.32%, which was comparable to a Pt CE-based DSSC (6.38%) under one sun illumination. Similarly, the maximum incident photon-to-charge carrier efficiency exhibited by MoS₂ CE-based DSSCs was 65.84%, which was also comparable to a Pt CE-based DSSC (68.38%). The study demonstrated that the marigold flower-like nanostructured MoS₂ films are a promising alternative to the conventional Pt-based CEs in DSSCs.

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Heteronuclear (Co-Ca, Co-Ba) 2,3-pyridinedicarboxylate complexes: synthesis, structure and physico-chemical properties

Three pyridine 2,3-dicarboxylate complexes have been synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffractometry. Their magnetic properties have also been studied by EPR and magnetisation measurements. The decomposition of such complexes in air leads to the generation of mixed metal oxides, as confirmed by powder X-ray diffraction.     

Piezoelectric Energy Harvesting from a Ferroelectric Hybrid Salt [Ph3MeP]4[Ni(NCS)6] Embedded in a Polymer Matrix

Organic–inorganic hybrid ferroelectrics are an exciting class of molecular materials with promising applications in the area of energy and electronics. The synthesis, ferroelectric and piezoelectric energy harvesting behavior of a 3d metal ion‐containing A₄BX₆ type organic–inorganic hybrid salt [Ph₃MeP]₄[Ni(NCS)₆] ( 1 ) is now presented. P‐E hysteresis loop studies on 1 show a remnant ferroelectric polarization value of 18.71 μC cm^?2, at room temperature. Composite thermoplastic polyurethane (TPU) devices with 5, 10, 15 and 20 wt % compositions of 1 were prepared and employed for piezoelectric energy harvesting studies. A maximum output voltage of 19.29 V and a calculated power density value of 2.51 mW cm^?3 were observed for the 15 wt % 1 ‐TPU device. The capacitor charging experiments on the 15 wt % 1 ‐TPU composite device shows an excellent energy storage performance with the highest stored energies and measured charges of 198.8 μJ and 600 μC, respectively.     

Surface cationization of cellulose to enhance durable antibacterial finish in phytosynthesized silver nanoparticle treated cotton fabric

Cellulose - Elimination of disease-causing bacteria from cotton fabrics is critically important to control several bacteria-mediated infections in humans. Antibacterial nanoparticles, particularly...