Synthesis and characterization of bis nitrato[4-hydroxyacetophenonesemicarbazone) nickel(II) complex as ionophore for thiocyanate-selective electrode.

The PVC based-ion selective electrode viz., bis nitrato[4-hydroxyacetophenone semicarbazone] nickel(II) as an ionophore was prepared for the determination of thiocyanate ion. The ionophore was characterized by FT-IR, UV-vis, XRD, magnetic moment and elemental analysis (CHN). On the basis of spectral studies an octahedral geometry has been assigned. The best performance was obtained with a membrane composition of 31% PVC, 63% 2-nitrophenyl octylether, 4.0% ionophore and 2.0% trioctylmethyl ammonium chloride. The electrode exhibited an excellent Nernstian response to SCN(-) ion ranging from 1.0 × 10(-7) to 1.0 × 10(-1)M with a detection limit of 8.6 × 10(-8)M and a slope of -59.4 ± 0.2 mV/decade over a wide pH range (1.8-10.7) with a fast response time (6s) at 25 °C. The proposed electrode showed high selectivity for thiocyanate ion over a number of common inorganic and organic anions. It was successfully applied to direct determination of thiocyanate in biological (urine and saliva) samples in order to distinguish between smokers and non-smokers, environmental samples and as an indicator electrode for titration of thiocyanate ions with AgNO3 solution.

Isolation, characterisation and antibacterial activity of new compounds from methanolic extract of seeds of Caesalpinia crista L. (Caesalpinaceae).

Phytochemical study on the methanolic extract of Caesalpinia crista afforded two novel compounds, 2-hydroxytrideca-3,6-dienyl-pentanoate and octacosa-12,15-diene along with known compounds 3-O-methylellagic acid 3'O-α-rhamnopyranoside, ß-sitosterol and sucrose. Compound 3-O-methylellagic acid 3'O-α-rhamnopyranoside is reported for the first time from the plant. Molecular structures, of isolated compounds, were elucidated by using the NMR spectroscopy in combination with IR and mass spectral data. All isolated compounds, extract and fractions were evaluated for in vitro antibacterial activity against various Gram-positive and Gram-negative bacterial strains and found to be significantly active against Staphylococcus aureus and methicillin-resistant S. aureus (minimum inhibitory concentration: 64-512 µg mL(- 1)).

Nickel analysis in real samples by Ni2+ selective PVC membrane electrode based on a new Schiff base.

A newly synthesized Schiff base 3-aminoacetophenonesemicarbazone (AAS) has been used for the preparation of Ni(2+) selective PVC membrane electrode. The proposed electrode exhibits a Nernstian response over the nickel concentration range of 1.0×10(-7) to 1.0×10(-2)mol L(-1) with a slope of 30.0±0.3 mV/decade of concentration. The limit of detection as determined from the intersection linear segment of the calibration plot is 5.1×10(-8) mol L(-1). The electrode shows good selectivity towards nickel with respect to several alkali, alkaline earth, transition and heavy metal ions. The response time of the electrode is very fast (≥10 s) and can be used for 17 weeks in the pH range of 2.0-9.8. The electrode can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working concentration range. To investigate the analytical applicability of the electrode, it was successfully applied as an indicator electrode in Ni(2+) ion potentiometric titration with EDTA, and in direct determination of nickel(II) in real samples.

Synthesis of Al nanoparticles: transmission electron microscopy, thermal and spectral studies.

Nanoparticles of Al(0) were synthesized by solution reduction process successfully. The influence of parameters on the size of Al(0) nanoparticles were studied and the referential process parameters were obtained. The morphology and structure of the synthesized Al(0) nanoparticles were characterized by Transmission Electron Microscopy (TEM), Powder X-ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), QELS Data and Infrared Spectroscopy (IR). The results show that nanoparticles of Al(0) are of high purity. XRD analysis revealed all relevant Bragg's reflection for crystal structure of Al metal. XRD spectrum also indicates there is no oxidation of Al(0) nanoparticles to aluminum oxide. TEM showed nearly uniform distribution of the particles in methanol and it was confirmed by QELS. Al(0) nanoparticles can be synthesized easily by reducing agent and are quite stable too.