Electrocatalytic determination of sumatriptan on the surface of carbon-paste electrode modified with a composite of cobalt/Schiff-base complex and carbon nanotube

The electrochemical oxidation of sumatriptan on the surface of carbon paste electrode modified with multi-walled carbon nanotube and cobalt methyl-salophen complex is studied by using cyclic voltammetry and polarization studies. The results indicate that the drug is irreversibly oxidized in a one electron oxidation mechanism. It was found that the peak potential shifted negatively with increasing pH, confirms that H(+) participate in the oxidation process. The electrode is shown to be very effective for the detection of sumatriptan in the presence of other biological reductant compounds. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of sumatriptan, ascorbic acid and uric acid, which makes it suitable for the simultaneous detection of sumatriptan in the presence of these compounds in clinical and pharmaceutical preparations. It can be concluded that multi-walled carbon nanotube and Shiff base complex have synergic effect on electroacatalytic oxidation of sumatriptan. A linear range of 1-1000μM and detection limit of 0.3μM was obtained for sumatriptan from DPV measurements using this electrode in 0.1M acetate buffered solution of pH 5.0. The electrode has been applied successfully for the determination of sumatriptan in synthetic serum and commercial tablets.     

Simple Hydrothermal Synthesis of Nickel Hydroxide Flower-Like Nanostructures

α-Ni(OH)₂ flower-like nanostructures were successfully synthesized through one-step hydrothermal method with nickel acetate tetrahydrate, ethylene-1,2-diamine (en), hexamethylenetetramine (HMT) and cetyltrimethylammonium bromide (CTAB) as morphology-directing agents. Optimum conditions to obtain high yield and pure phase α-Ni(OH)₂ were identified by varying experimental parameters such as: en, HMT and CTAB concentration and reaction temperature. The products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared and thermogravimetric analysis. These results indicated that the α-nickel hydroxide contains water molecules and anions. The hierarchical NiO nanostructures were obtained by the as-synthesized α-Ni(OH)₂ nanostructures annealed at 300 °C for 4 h.     

An Ab Initio Study of Conformational Energies in Dioxo-, Trioxo-, and Tetroxo-Dithianes

Ab initio Hartree–Fock calculations at the HF/6-31G* level of theory for geometry optimization and the MP2/6-31G*//HF/6-31G* and B3LYP/6-311G(2df,p)//HF/6-31G* levels for a single point total energy calculation are reported for the important energy-minimum conformations of 1,1-dioxo-thiane (2), 1,1-dioxo-1,2-dithiane (3), 1,1-dioxo-1,3-dithiane (4), 1,1-dioxo-1,4-dithiane (5), 1,1,2-trioxo-1,2-dithiane (6), 1,1,3-trioxo-1,3-dithiane (7), 1,1,4-trioxo-1,4-dithiane (8), 1,1,2,2-tetroxo-1,2-dithiane (9), 1,1,3,3-tetroxo-1,3-dithiane (10), and 1,1,4,4-tetroxo-1,4-dithiane (11). According to the MP2/6-31G*//HF/6-31G* calculations, compound 5 is more stable than 3 and 4 by 7.8 and 8.9 kJ mol^?1, respectively. The axial geometries of 6 and 8 are more stable than the equatorial forms by 21.4 and 19.1 kJ mol^?1, respectively, but the equatorial form of 7 is 4.1 kJ mol^?1 more stable than the axial geometry. Compound 11 is more stable than 9 and 10 by 49.3 and 31.0 kJ mol^?1, respectively.     

An Experimental and Theoretical Study on Influence of H‐bonding on the Synthesized Azo Derivatives Structures

We have reported a simple and efficient reaction for the synthesis of some new functionalized azo structures which were prepared by electron deficient acetylenic compounds in the presence of triphenylphosphine. The characterization of the synthesized azo compounds has been determined by FTIR, UV‐Vis, ¹H NMR, ¹³C NMR and Mass spectroscopic techniques. The influence of H‐bonding on the products has been shown by different experimental analysis. Also, the regioselectivity of the reaction, tautomerization equilibrium and the stability of products was investigated using DFT calculations at the B3LYP/6‐31G level of theory.     

In Situ Synthesis and Characterization of Nano ZnO on Wool: Influence of Nano Photo Reactor on Wool Properties

This study has been carried out to synthesize nano ZnO on wool fabric and also to investigate influences of nano photo reactors on wool fabric characteristics. Zinc acetate has been used as a precursor and the synthesis process has been done in water and water/ethanol media. The treated wool fabrics were heated at 80°C for 10 h to dehydrate Zn(OH)₂ obtaining ZnO. The fabric samples were then subjected to daylight for 7 days to examine the influence of nano ZnO photo reactor on the fabric properties. SEM images revealed the embedding of ZnO nanoparticles on the fabrics and X‐ray diffraction verified the nanoparticles composition. The Yellowness Index (YI) of the fabrics was measured with Color Eye XTH that has been reduced with increasing pH, Zn(CH₃COO)₂ concentration, ethanol and heating. The lower water contact angle and time of water absorption confirmed higher hydrophilic properties of the treated fabrics. Interestingly, a higher tensile strength obtained on the wool fabrics proved the interaction of ZnO with protein chains of wool, which was verified through lower alkali solubility of treated fabric with nano ZnO and confirmed more benefits of the in situ synthesis process.     

Syntheses and characterization of mixed-chelate copper(II) complexes containing different counter ions; spectroscopic studies on solvatochromic properties

Solvatochromic mixed-chelate copper(II) complexes, [Cu(Cl-acac)(diamine)]X (where Cl-acac = 3-chloroacetylacetonate ion, diamine = N,N′-dimethyl,N′-benzyl-1,2-diaminoethane and X = B(Ph)₄⁻, PF₆⁻, BF₄⁻ and ClO₄⁻), have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV-Vis and IR spectroscopies. Single crystals of [Cu(Cl-acac)(diamine)(H₂O)]PF₆, complex 2, were also characterized by X-ray diffraction. The influence of the solvent polarity and counter ions on the ν_max values of the d-d bands of the complexes have been investigated by means of visible spectroscopy. All the complexes demonstrated negative solvatochromism. A multi-parametric equation has been utilized to explain the solvent effect on the d-d transition of the complexes using SPSS/PC software. The stepwise multiple linear regression (SMLR) method demonstrated that the donor power of the solvent plays the most important role in the solvatochromism of the compounds. The relative donor power of the anions X was determined by visible spectra in the solvent dichloromethane.     

Molecular dynamics simulation of manipulation of metallic nanoclusters on stepped surfaces

Molecular dynamics simulations are carried out to investigate the manipulation of metallic clusters on stepped surfaces. Five surface forms are considered in the simulations. The system parts are made of pure transition metals and Sutton-Chen many-body potential is used as interatomic potential. The conditions which are subjected to change in the tests include: materials used for particles and substrate, and surface step conditions. In addition to qualitative observations, two criteria which represent the particle deformation and substrate abrasion are utilized as evaluation tools and are computed for each case. Simulation results show the effect of the aforementioned working conditions on the particle behavior as well as changes in the pushing forces. Obtaining this sort of knowledge is highly beneficial for further experiments in order to be able to plan the conditions and routines which guarantee better success in the manipulation process.