Preparation,characterization and antifungal properties of transition metal ion complexes of quadridentate N3S ligands

Summary New metal complexes [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; NNNS^– = anion of the quadridentate ligands formed from S-methyl--N-(2-aminophenyl)-methylenedithiocarbazate and pyridine-2-aldehyde or 6-methylpyridine-2-aldehyde; X = Cl, NCS, NO₃ or I) and [Co(NNNS)Cl₂]·2H₂O have been prepared and characterized by elemental analysis and conductance measurements. Magnetic and spectroscopic evidence support a five-coordinate structure for [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; X = Cl, NCS) and a squareplanar structure for [Ni(NNNS)]X (X = NO₃ or I). The [Co(NNNS)Cl₃]·2H₂O complex is low-spin and octahedral. The Schiff bases and some of their metal complexes were tested against three pathogenic fungi, Alternaria alternata, Curvularia geniculata and Fusarium palidoroseum. The metal complexes are less fungitoxic than the free ligands.     

Synthesis,characterization and biological activities of some nickel(II) complexes of tridentate NNS ligands formed by condensation of 2-acetyl-and 2-benzoylpyridines with S-alkyldithiocarbazates

Summary Nickel(II) complexes of four tridentate NNS Schiff base ligands, derived by condensing 2-acetyl-and 2-benzoylpyridine with S-methyl- and S-benzoyldithiocarbazate, have been prepared and characterized. The monoligated complexes, [Ni(NNS)X] (NNS = anionic ligand; X = Cl, Br, NCS, I) are diamagnetic and square-planar, whereas the bis-ligand complexes, [Ni(NNS)₂] are paramagnetic and tetragonal. The Schiff bases are fungitoxic towards A. solani, F. equisetti and M. phaseolina (approaching the toxicity of the commercial fungicide Nystatin), but the nickel(II) complexes are less fungitoxic than the free ligands.     

A nanostructured ion-imprinted polymer for the selective extraction and preconcentration of ultra-trace quantities of nickel ions

We describe a nanostructured ion-imprinted polymer (IIP) for the selective preconcentration of Ni(II) ions. It was obtained by bulk polymerization from 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), alizarin red S (the nickel-binding ligand), and nickel (the template ion) in acetonitrile solution. The IIP particles were characterized by elemental analysis, X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetric and differential thermal analysis, and by scanning electron microscopy. Imprinted Ni(II) ions were removed from the polymeric structure using 5 % HCl as the eluting solvent. The material is capable of selectively binding Ni(II) from solutions at pH values between (pH 8.0 being best). Both the sorption and desorption process occur within 5 min. The maximum sorbent capacity of the ion imprinted polymer is 73 mg g^?1. Following desorption, Ni(II) was determined by FAAS, with relative standard deviation and limit of detection of 3.4 % and 0.15 ng mL^?1, respectively. The method was applied to the determination of nickel in certified reference materials (soil and polymetallic gold ore), fish, vegetables, river sediments, and river water.

High-order compact solution of the one-dimensional heat and advection–diffusion equations

In this work, we propose a high-order accurate method for solving the one-dimensional heat and advection–diffusion equations. We apply a compact finite difference approximation of fourth-order for discretizing spatial derivatives of these equations and the cubic C¹$C^1$-spline collocation method for the resulting linear system of ordinary differential equations. The cubic C¹$C^1$-spline collocation method is an A-stable method for time integration of parabolic equations. The proposed method has fourth-order accuracy in both space and time variables, i.e. this method is of order O(h⁴,k⁴)$O(h^4\text{,}{k}^4)$. Additional to high-order of accuracy, the proposed method is unconditionally stable which will be proved in this paper. Numerical results show that the compact finite difference approximation of fourth-order and the cubic C¹$C^1$-spline collocation method give an efficient method for solving the one-dimensional heat and advection–diffusion equations.     

Continuous ant colony system and tabu search algorithms hybridized for global minimization of continuous multi-minima functions

A new hybrid optimization method, combining Continuous Ant Colony System (CACS) and Tabu Search (TS) is proposed for minimization of continuous multi-minima functions. The new algorithm incorporates the concepts of promising list, tabu list and tabu balls from TS into the framework of CACS. This enables the resultant algorithm to avoid bad regions and to be guided toward the areas more likely to contain the global minimum. New strategies are proposed to dynamically tune the radius of the tabu balls during the execution and also to handle the variable correlations. The promising list is also used to update the pheromone distribution over the search space. The parameters of the new method are tuned based on the results obtained for a set of standard test functions. The results of the proposed scheme are also compared with those of some recent ant based and non-ant based meta-heuristics, showing improvements in terms of accuracy and efficiency.     

Thiol‐functionalized fructose‐derived nanoporous carbon as a support for gold nanoparticles and its application for aerobic oxidation of alcohols in water

Gold nanoparticles supported on thiol‐functionalized fructose‐derived nanoporous carbon (AuNPs@thiol‐Fru‐d‐NPS) were found to be a simple bench‐top, biocompatible, recyclable and selective catalytic system for the aerobic oxidation of various types of alcohols into their corresponding aldehydes and ketones at room temperature under the environmentally friendly conditions with excellent yields. Copyright © 2014 John Wiley & Sons, Ltd.     

Kinetic investigations into the synthesis of disulphides via tetrathiomolybdate as a sulphur-transfer reagent

Kinetic and mechanistic aspects of the conversion of halides to disulphides using benzyl triethyl ammonium tetrathiomolybdate as sulphur-transfer reagent were investigated. The reaction follows a 1:1 stoichiometry with overall second-order kinetics and involves the formation of monosulphides in addition to disulphides. In the light of our observations, we propose a nucleophilic substitution: carbon–metal–carbon (S_N-CMC) reaction mechanism. The proposed mechanism, besides accounting for all of our experimental observations, also explains many aspects of such reactions that have been reported earlier by various groups.     

Endoscopic effects on the peristaltic flow of an Eyring–Powell fluid

This study investigates the peristaltic flow of Eyring–Powell fluid in an endoscope. The governing equations for Eyring–Powell are modeled in cylindrical coordinates under the assumption of long wavelength and low Reynolds number approximation. The resulting nonlinear differential equations are solved analytically and numerically by employing perturbation method and shooting technique. Numerical integration have been done for pressure rise and frictional forces. Comparative study have been made for both the solutions to see the validity of the results. The effects of various emerging parameters are investigated for five different peristaltic waves. (Basically peristaltic phenomena is a natural phenomena so it is not necessary that peristaltic wave be always a sinusoidal wave it could be multisinusoidal, triangular, trapezoidal and square waves for example heartbeats.) Streamlines have been plotted at the end of the article.     

Peristaltic flow of a Jeffrey‐six constant fluid in a uniform inclined tube

In this work, we studied the peristaltic flow of a Jeffrey‐six constant fluid in a uniform tube. The governing equations of the Jeffrey‐six constant fluid were simplified by using the assumptions of long wave length and low Reynolds number approximation. The simplified form of equations were solved using the perturbation, homotopy analysis and finite difference methods. The comparison of the three solutions are shown graphically. The variation of pressure rise and frictional forces with the different parameters were also examined numerically. Results are presented at the end of the article. Copyright © 2011 John Wiley & Sons, Ltd.     

Novel 2,2′-bipyridine palladium(II) complexes with glycine derivatives: synthesis, characterization, cytotoxic assays and DNA-binding studies

The two water-soluble designed palladium(II) complexes, [Pd(bpy)(pip-Ac)]NO₃ and [Pd(bpy)(mor-Ac)]NO₃, (where bpy is 2,2′-bipyridine, pip-Ac is 1-piperidineacetato and mor-Ac is 4-morpholineacetato) have been synthesized and characterized by elemental analyses, molar conductivity measurements and spectroscopic methods (FT-IR, ¹H NMR, UV–Vis). The complexes have been tested for in vitro cytotoxic activity against human breast cancer cell line, T47D. The binding of these complexes with DNA has been investigated by absorption spectroscopy, fluorescence titration spectra, EB displacement and gel chromatography. The results suggest that the complexes can bind to DNA cooperatively through a static mechanism at low concentrations (~0.57 μM). The thermodynamic parameters indicated that the van der Waals and hydrogen binding might play a major role in the interaction of these complexes with DNA.