A complex of Ni(II) with 2,6-diacetylpyridinedihydrazone (L) towards nickel(II) has been prepared and characterized by means of elemental analyses, IR, electronic spectra and single crystal X-ray analyses. [NiL(2)](NO(3)) was crystallized in the tetragonal space group P-4 21 c. The complex exhibits the expected coordination sphere with six nitrogen atoms coordinated to the central Ni(II) with a deformation from pseudo-octahedral geometry. Antimicrobial activities of the ligand and its complex were investigated.

Surface modification of clay minerals has become increasingly important for improving the practical applications of clays such as fillers and adsorbents. An investigation was carried out on the surface modification of sepiolite with aminopropylsilyl groups in 3-aminopropyltriethoxysilane (3-APT). The zeta potential of the modified sepiolite suspensions was measured as a function of initial electrolyte concentration and equilibrium pH using a Zeta Meter 3.0 for modified sepiolite. The utility of the 3-APT-modified sepiolite was investigated as an adsorbent for removal of various heavy metal ions such as Fe, Mn, Co, Zn, Cu, Cd and Ni from aqueous solutions. The effects of various factors on the adsorption, such as pH, ionic strength and temperature of the solution were studied. The results showed that the amount adsorbed increases with solution pH in the pH range of 1.5 and 7.0; indicated that the modified sepiolite adsorbed Fe and Mn ions more than other metal ions such as Co, Zn, Cu, Cd and Ni. It was found that the temperature had an important effect on metal ion adsorption by the modified sepiolite. The adsorption isotherm has been determined and data have been analyzed according to the Langmuir and Freundlich models. (C) 2007 Elsevier B.V. All rights reserved.

Tautomer proportions of acetylacetone (acac) in six different solvents are investigated with a new method by means of experimental absorptions (A) and theoretical absorption coefficients (e). The specific absorption bands (key bands) for keto and enol tautomers were obtained from recorded FT-IR spectra in related solution at room temperature. The molar absorption coefficients for key bands of both keto and enol tautomers were calculated, which is impossible to obtain with experimental methods for individual isomers in equilibrium. The Lambert-Beer equation is used to detect tautomer proportions. The obtained results are in consistence with literature. The most stable enol tautomer is found to be (86%) in CCI4 and the keto tautomer is found to be most stable in DMSO (48%). (C) 2012 Elsevier B.V. All rights reserved.

In situ complexation reactions between 2,6-bis(3,5-dimethylpyrazoyl)pyridine (bdmpp) and some transition metals (Cu(2+), Co(2+) and Ni(2+)) were studied with a new method in liquid cell using FT-IR. In this method, the spectrum of the solution of ligand was defined as a background, and then the changes in the FT-IR spectra by the addition of the metal salts were investigated. This method allows one to obtain the spectra of the ligand-metal complex before yielding the solid-state product. Complexation ratios (M/L) of these metals with bdmpp were found 1/1, 1/2 and 1/2, for Cu, Co and Ni, respectively. Studying with Mg(2+) and Ca(2+) ions showed that there were no interaction between bdmpp and these metal ions in methanol. (C) 2011 Elsevier B.V. All rights reserved.

The relative rotamer, dimer and tautomer concentrations of diacetamide have been studied by means of infrared spectroscopy, with the recorded spectra being analyzed employing results from density functional theory calculations. It is observed that the cis-trans monomeric form of diacetamide (1) is found to be the most stable isomer in all studied solvents, with trans-trans diacetamide (2) being found to be 20% of total diacetamide in methanol. While the dimer form of diacetamide (3) is present only in carbon-tetrachloride (about 34% of the total), its tautomeric forms (4, 5) are not favorable in any of the studied solvents. (C) 2011 Elsevier B.V. All rights reserved.

Monitoring of a reaction in FrIR liquid cell has complex spectral futures due to the presence of solvent, unreacted reagents; acid catalysis and other additives. The current work was performed to study the kinetics of the reaction between benzaldehyde and aniline by simultaneous time dependent observation in FTIR liquid cell. Since the FTIR liquid cell used in this work was a closed system, background defining method allowed us to observe the changes in the concentration of each component in the liquid cell at different side of absorbance or transmittance axes. The changes in concentration arising from the reaction provide both the spectra and amount of the product and reagent, independently without having to isolate them from the reaction mixture. Therefore, it would be possible to follow the amount of decreases in concentration of the reagent and conversely, increases in concentration of the product. Consequently, using this method the reaction of benzaldehyde and aniline was found to go to equilibrium in chloroform. (c) 2006 Elsevier B.V. All rights reserved.

A single crystal of the copper(II) compound, [Cu(bdmpp)(SeCN)(2)], 2, was obtained and its crystal structure was determined by X-ray diffraction methods. The complex was characterized by elemental, thermal and FTIR analysis. The FTIR analysis of the complex clearly shows the SeCN peaks at 2096 and 2061 cm(-1) which did not exist in the free organic ligand ( bdmpp). X-ray analysis showed that 2 crystallized in the monoclinic space group P2(1)/c. Cu(II) has a distorted trigonal bipyramidal coordination involving three N atoms from the ligand and two N atoms from the selenocyanate group.

The metal ion adsorption and electrokinetic properties of sepiolite modified by 3-(trimetoxysilyl)propyl metaacrylate was studied. The characterization of modified sepiolite was made by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron micrograph (SEM), and differential thermal analysis/thermogravimetry (DTA/TG). The adsorption behavior of Fe(III), Mn(II), Co(II), Zn(II), Cu(II), and Cd(II) metal ions on modified sepiolite from aqueous solutions was investigated as a function of equilibrium pH, temperature, and ionic strength. The adsorption experiments were carried out using a batch method. The initial and final concentrations of heavy metals were determined by means of atomic absorption spectrophotometry. The zeta potential of the modified sepiolite suspensions was measured as a function of metal ion concentration and equilibrium pH using a Zeta Meter 3.0. The results showed that the amount of adsorbed metal ions increased with solution pH, and that the modified sepiolite adsorbed Cu(II) and Mn(II) ions more than other metal ions. It was found that the temperature had an important effect on metal ion adsorption and that the adsorption process was endothermic in nature. Equilibrium isotherms for the adsorption of metal ions were measured experimentally. Results were analyzed by the Freundlich and Langmuir equations and determined the characteristic parameters for each adsorption isotherm. The isotherm data were reasonably well correlated by Langmuir isotherm. Maximum monolayer adsorption capacity of modified sepiolite for Cu(II), Mn(II), Zn(II), Fe(III), Co(II), and Cd(II) metal ions was calculated from 12.3x10(-5), 11.7x10(-5), 9.0x10(-5), 8.2x10(-5), 5.7x10(-5), and 1.8x10(-5)molL(-1), respectively. The affinity order of adsorption was Cu(II)>Mn(II)>Zn(II)-Fe(III)>Co(II)>Cd(II). The results indicate that modified sepiolite is good adsorbent for the removal of metal ions from aqueous solutions.

The mononuclear nickel complex NiL (LH2 = N,N'-bis(salicylidene)-1,3-diaminopropane) can be transformed into the tetranuclear complex [NiL(H2O)Pb(SCN)2(DMF)]2 in the aid of SCN-, DMF (dimethylformamide) and Pb(II) ions. The complex was characterized by elemental analysis and FTIR investigation. The crystal structure reveals it is a nonlinear Ni(II)-Pb(II)-Pb(II)i-Ni(II)i (i: 1-x, 1-y, 1-z) heterotetranuclear complex and crystallizes in the triclinic space group P1. The Ni(II) and Pb(II) ions have a distorted octahedral coordination geometry. There are three kinds of mu-bridge in the molecule between the metal ions. Each pair of Ni and Pb ions in the asymmetric unit is equatorially linked by two phenolic oxygen bridging atoms of N,N'-bis(salicylidene)-1,3-propanediaminato (salpd(2-), C17H16N2O2(2-)) ligand. The dinuclear centres from tetranuclear clusters Ni-Pb(i) and Ni(i)-Pb pairs are bridged by two mu-1,3-SCN groups. Pb(II) and Pb(II)i ions are also bridged by the oxygen atoms of DMF molecules. The tetranuclear units are hydrogen bonded by two O-H...N intermolecular interactions along the c-axis. The complex was screened for antibacterial and antifungal activities by the disc diffusion and microtiter plate techniques using DMF as solvent. The minimum inhibitory concentration values were calculated. It has been found that antimicrobial activities of the complexes are higher than the free ligand.

Surface modification of clays has become increasingly important due to the practical applications of clays such as fillers and adsorbents. The surface modification of sepiolite with [3-(2-aminoethylamino)propyl]trimethoxysilane has been employed. The modified sepiolite surface was investigated by FTIR, XRD and DTA/TG analysis. It was found that the chemical bonding takes place between the hydroxyl groups and/or oxygen atoms within the structure of sepiolite and methoxy groups of [3-(2-aminoethylamino)propyl]trimethoxysilane. The changes on electrokinetic properties of modified sepiolite particles were studied by measuring the zeta potential of particle as a function of metal concentration and equilibrium pH of solution. It was found that the zeta potential of the clay particles was always negative independent of the metal concentration in solution. This study also provides some evidence for the adsorption of metal ions on modified sepiolite. The adsorption of metal ions onto modified sepiolite has varied with the type of metal cations. The available basic nitrogen centers covalently bonded to the sepiolite skeleton were studied for Co(II), Cu(II), Mn(II), Zn(II), Fe(III) and Cd(II) adsorption from aqueous solutions. It was found that the amount of metal ion adsorbed onto modified sepiolite increases with increase in solution equilibrium pH and temperature, whereas it generally decreases with the ionic strength. The experimental data were correlated reasonably well by the Langmuir adsorption isotherm and the isotherm parameters (q(m) and K) were calculated. The ability to adsorb the cations gave a capacity order of Zn(II) > Cu(II) similar to Co(II) > Fe(III) > Mn(II) > Cd(II) with affinities of 2.167x 10(-4), 1.870x10(-4), 1.865x10(-4), 1.193x10(4), 0.979x 10(-4) and 0.445x 10(-4) mol g(-1), respectively.