Mixed-Ligand Nickel(II) Complexes Containing Sulfathiazole and Cephalosporin Antibiotics: Synthesis, Characterization, and Antibacterial Activity

Nickel(II) reacts with cephalosporins plus sulfathiazole (Hstz) to form the following mixed-ligand complexes of general formulae [Ni(L)(stz)(H2O)x]n (L1,4, x = 1; L2,3, x = 0; L = monoanion of cefazolin HL1, cephalothin HL2, cefotaxime HL3, ceftriaxone HL4) and [Ni(L5)(stz)]Cl (cefepime L5), which were characterized by physicochemical and spectroscopic methods. Their spectra indicated that cephalosporins are acting as multidentate chelating agents, via the lactam carbonyl and carboxylate and Nazomoieties. The complexes are insoluble in water and common organic solvents but soluble in DMSO, where the [Ni(L5)(stz)]Cl complex is 1 : 1 electrolyte. They probably have polymeric structures. They have been screened for antibacterial activity, and the results are compared with the activity of commercial cephalosporins.
Автор: J. R. Anacona and Maried Lopez 
Рік видання: 2012. Тип документу: Складова частина документу 
Розмір: 874 Кб     Кількість завантажень: 41

Surfactant-Assisted Sol-Gel Synthesis of TiO2 with UniformParticle Size Distribution

TiO2 materials were prepared froma titanium isopropoxide precursor by sol-gel processing in watermedia with or without various templates (polyethylenimine or Pluronic P-123). The photocatalytic efficiency of the samples was found to depend strongly on the use of and type of template added. Titania/Pluronic sols resulted in homogeneous anatase TiO2—rutile with uniform particle size distribution after calcination (400◦C). Optical properties of the samples were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol-gel process retarded crystallization of the anatase and rutile titania, which resulted in smaller grain sizes and presumably a larger active surface area. The morphology of the surfaces was obtained by AFM techniques. The highest photobleaching rate was found for samples deposited from the sol with the addition of the Pluronic P-123 surfactant, and it was almost twice as high as that for films deposited from sols with polyethylenimine.
Автор: O. L. Galkina, V. V. Vinogradov, A. V. Agafonov, and A. V. Vinogradov 
Рік видання: 2011. Тип документу: Складова частина документу 
Розмір: 2,54 Мб     Кількість завантажень: 41

Novel Nonsymmetrically p-Benzyl-Substituted (Benz)imidazoleN-Heterocyclic Carbene-Silver(I) Acetate Complexes: Synthesis and Biological Evaluation

Автор: Frauke Hackenberg, Anthony Deally, Grainne Lally, SinaMalenke, HelgeM¨uller-Bunz, Francesca Paradisi, Siddappa Patil, Daniela Quaglia, and Matthias Tacke 
Рік видання: 2012. Тип документу: Складова частина документу 
Розмір: 1,37 Мб     Кількість завантажень: 41

Spectral, NLO, Fluorescence, and Biological Activity of Knoevenagel Condensate of β-Diketone Ligands and Their Metal(II) Complexes

Transition metal complexes of various acetylacetone-based ligands of the type ML (where M = Cu(II), Ni(II), Co(II); L = 3- (aryl)-pentane-2,4-dione) have been synthesized. The structural features have been derived fromtheir elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, H1NMR, mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are nonelectrolytic in nature. Spectroscopic and other analytical data of the complexes suggest square planar geometry for copper(II), cobalt(II), and nickel(II) complexes of 3-(3-phenylallylidene)pentane-2,4-dione and octahedral geometry for other metal(II) complexes. The redox behaviors of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against bacteria and fungus. The metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands was found to have considerable effect compared to that of urea and KDP.
Автор: S. Sumathi, C. Anitha, P. Tharmaraj, and C. D. Sheela 
Рік видання: 2011. Тип документу: Складова частина документу 
Розмір: 609 Кб     Кількість завантажень: 41

Crystal Structure of [Bis(L-Alaninato)Diaqua] Nickel(II) Dihydrate

The title complex, [Ni(C3H6O2N)2(H2O)2]·2H2O, has been prepared from nickel(II) chloride in aqueous solution by adding L-alanine and potassium hydroxide. It has been crystallized from aqueous solution, and its structure was determined by X-ray structure analysis. The nickel(II) ion adopts distorted octahedral coordination geometry with two bidentate L-alanine molecules and two watermolecules. The complex is neutral and dihydrated. The crystal structure shows the hydrogen bonding between water and amide hydrogens within the lattice, and each fragment of the complex contains two water molecules as hydrated water. The L-alaninato ligand skeleton of the compound adopts the most stable trans-III configuration in the solid state. The alternating two five-membered chelate rings are in the stable gauche conformation.
Автор: Awni Khatib, Fathi Aqra, David Deamer, and Allen Oliver 
Рік видання: 2009. Тип документу: Складова частина документу 
Розмір: 1,46 Мб     Кількість завантажень: 41

Synthesis, Spectroscopic, Anticancer, and Antimicrobial Properties of SomeMetal(II) Complexes of (Substituted) Nitrophenol Schiff Base

The Schiff base, 2-[(2,3-dihydro-1H-inden-4-ylimino)methyl]-5-nitrophenol coordinates to Mn(II), Cu(II), Zn(II), and Pd(II) ions through the phenolic O and imine N atoms. The complexes are characterized by physicochemical and spectroscopic methods. The metal complexes formed as [ML2]xH2O with exception of the Cu(II) complex which is anhydrous. Spectroscopic data corroborate the adoption of a four-coordinate, tetrahedral geometry for theMn(II), and Zn(II) complexes, and a four-coordinate, square planar geometry for the Cu(II) and Pd(II) complexes. None is an electrolyte in DMSO. The in vitro anticancer activities of the metal free ligand, Cu(II), Zn(II), and Pd(II) complexes against MCF-7 (human breast adenocarcinoma) and HT-29 (colon carcinoma) cells reveal that the Pd(II) complex has the best cytotoxic activity against MCF-7 cells with an IC50 of 5.94 μM, which is within the same order of activity as cisplatin. Furthermore, the ligand and the Zn(II) complex exhibit broad-spectrum activity against two gram-positive bacteria, three gram-negative bacteria, and a fungus with inhibitory zones range of 10.0–20.0 and 10.0– 17.0 mm, respectively.
Автор: AderojuA. Osowole, Ingo Ott, and Oladunni M. Ogunlana 
Рік видання: 2012. Тип документу: Складова частина документу 
Розмір: 565 Кб     Кількість завантажень: 41

Mechanistic Aspects of Osmium(VIII) Catalyzed Oxidation of L-Tryptophan by Diperiodatocuprate(III) in Aqueous Alkaline Medium: A Kinetic Model

In presence of osmium(VIII), the reaction between L-tryptophan and diperiodatocuprate(III) DPC in alkaline medium exhibits 1:4 stochiometry (L-tryptophan:DPC). The reaction shows first-order dependence on [DPC] and [osmium(VIII)], less than unit order in both [L-tryptophan] and [alkali], and negative fractional order in [periodate]. The active species of catalyst and oxidant have been identified. The main products were identified by spectral studies and spot test. The probable mechanism was proposed and discussed.
Автор: Nagaraj P. Shetti, Ragunatharaddi R. Hosamani, and Sharanappa T. Nandibewoor 
Рік видання: 2008. Тип документу: Складова частина документу 
Розмір: 587 Кб     Кількість завантажень: 41

Exchange Interaction in Complex Bis[(1,3-Dithiole-2-Thione- 4,5-Dithiolato)-di-(Carbonyl)-Cyclopentadienyl Iron(II)]

The splitting of the quasidegenerate electronic states in dinuclear bis[(1,3-dithiole-2-thione-4,5-dithiolato)-di-(carbonyl)- cyclopentadienyliron (II)] complex with the bridging, S–S coupled, dimerized sulfur-rich dithiolate ligands, [Fe(C5H5)(CO)2 (C3S5-C3S5)Fe(C5H5)(CO)2] (I) was found by the means of M¨ossbauer spectroscopy and by the measurement of the temperature dependence of magnetic susceptibility in a wide temperature range from 2 K to 300 K. The experimental results were confirmed by the calculations of the singlet and triplet states of the complex, as well as of the distribution of spin density within the bounds of the DFT method in the B3LYP/6-31(dp)G basis. In the more stable triplet state, the spin density is significantly delocalized, which is a characteristic of olefindithiolate complexes.
Автор: S. V. Vitushkina, D. V. Ziolkovskiy, V. A. Starodub, I. A. Presniakov, A. V. Sobolev, M. Kajnakov´ a, A. Radv´akova, and A. Feher 
Рік видання: 2009. Тип документу: Складова частина документу 
Розмір: 819 Кб     Кількість завантажень: 41

Kinetics of Reduction of Colloidal MnO2 by Glyphosate in Aqueous and Micellar Media

The kinetics of the reduction of colloidal MnO2 by glyphosate has been investigated spectrophotometrically in an aqueous and micellar (cetyltrimethylammonium bromide, sodium lauryl sulfate) media. The reaction follows first-order kinetics with respect to colloidal MnO2 in both the aqueous and micellar media. The rate of oxidation increases with increase in [glyphosate] in the lower concentration range but becomes independent at its higher concentrations. The addition of both the anionic (NaLS) and cationic (CTAB) micelles increased the rate of reduction of colloidal MnO2 by glyphosate while the nonionic TX-100 micelles did not influence the rate of reaction. In both aqueous and micellar media, the oxidation of glyphosate occurs through its adsorption over colloidal MnO2 surface. The reaction in micellar media was treated by considering the pseudophase model. The values of reaction rates and binding constants in the presence of micelles were determined.
Автор: Uzma Aisha, Qamruzzaman, and M. Z. A. Rafiquee 
Рік видання: 2011. Тип документу: Складова частина документу 
Розмір: 678 Кб     Кількість завантажень: 41

Syntheses and Crystal Structures of Two Transition Metal Complexes (M=Mn and Co) Containing Malonate and Reduced Imino Nitroxide Radicals

Автор: Jing Chen, You-Juan Zhang, Bing-Chang Qin, Hui-Min Zhu, and Yu Zhu 
Рік видання: 2011. Тип документу: Складова частина документу 
Розмір: 3,45 Мб     Кількість завантажень: 41

Speciation Studies of L-Histidine Complexes of Pb(II), Cd(II), and Hg(II) in DMSO-WaterMixtures

Equilibrium study on complex formation of L-histidine with Pb(II), Cd(II), and Hg(II) has been investigated pH metrically in DMSO-water mixtures (0–60% v/v) at 303 K and 0.16 mol L−1 ionic strength. The predominant species detected for Pb(II) and Cd(II) areML2H4, ML2H3, ML2H2, ML2H, andML2 and those for Hg(II) are ML2H4, ML2H3, ML2, and ML. The appropriateness of experimental conditions is verified by introducing errors intentionally in the concentrations of ingredients. The models containing different numbers of species were refined by using the computer program MINIQUAD75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of stability constants of the complexes with dielectric constant of the medium is attributed to the electrostatic and nonelectrostatic forces. The species distribution and the plausible equilibria for the formation of the species are also presented.
Автор: K. Bharath Kumar Naik, B. Ananda Kumar, S. Raju, and G. Nageswara Rao 
Рік видання: 2012. Тип документу: Складова частина документу 
Розмір: 788 Кб     Кількість завантажень: 41

Synthesis and Characterization of Bis(4-methylbenzylammonium) Tetrachloridocadmate(II)

Автор: R. Kefi, M. Zeller, F. Lefebvre, and C. Ben Nasr 
Рік видання: 2011. Тип документу: Складова частина документу 
Розмір: 1,92 Мб     Кількість завантажень: 41

Synthesis, Structure, and Thermal Stability of Supramolecular Polymers with 1D Chain: [M(BPP)2(TBTA)(H2O)2]n[M = Mn(1), Co(2)]

Two supramolecular polymers [M(BPP)2(TBTA)(H2O)2]n[M = Mn(1), Co(2)] have been constructed from 2,3,5,6-tetrabromoterephthalic acid (H2TBTA) and 1,3-bis(4-pyridyl)propane (BPP) ligands in water-methanol dissolvant. Single-crystal X-ray and powder diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis were employed to characterize all samples. Both of the complex compounds 1 and 2 belong to triclinic crystal system with P-1 space group. The crystal structures analysis indicates that the metal atom coordinated by two carboxylate groups from different TBTA ligands, two BPP, molecules and two H2O molecules formed a slightly distorted octahedral configuration. The compounds of 1 and 2 are 1D chains made with TBTA spacers, BPP molecules, and H2O molecules.
Автор: Yan Liu, Ling-Ling Gao, Xu-Yan Lv, Jian-Feng Liu, and Tuo-Ping Hu 
Рік видання: 2012. Тип документу: Складова частина документу 
Розмір: 2,31 Мб     Кількість завантажень: 41

Synthesis and Crystal Structure Differences between Fully and Partially Fluorinated β-DiketonateMetal (Co2+, Ni2+, andCu2+) Complexes

Coordination complexes, [Co2(1)4(H2O)2] (2), [Ni2(1)4(H2O)2] (3), and [Cu(1)2] (4), by using an asymmetric and partially fluorinated 3-hydroxy-3-pentafluorophenyl-1-phenyl-2-propen-1-one (H1) have been prepared, and the structures were investigated to compare with the corresponding fully fluorinated complexes of [Co2(5)4(H2O)2] (6), [Ni2(5)4(H2O)2] (7), and [Cu(5)2] (8) with bis(pentafluorobenzoyl)methane (H5) and to understand the fluorine-substituted effects. While the coordination mode of the partially fluorinated complexes was quite similar to the fully fluorinated complexes, the intra- and intermolecular π-interactions of the ligand moieties were highly influenced by the fluorination effects; the arene-perfluoroarene interactions were observed in complexes 2 and 3 as a reason of the dinucleation. In this paper, we describe detail structures of the protonated form of the ligand, H1, and complexes 2–4 by X-ray crystallographic studies.
Автор: Akiko Hori and Masaya Mizutani 
Рік видання: 2011. Тип документу: Складова частина документу 
Розмір: 3,17 Мб     Кількість завантажень: 41

Crystal Structure and Thermal Behavior of Two New Supramolecular Complexes Templated with 1,2,4,5-Benzenetetracarboxylic Acid

Templated coordination polymers [Ni(H2O)4(bipy)](BTA)0.5·H2O (1) and [Co(H2O)4(bipy)](BTA)0.5·H2O (2) (bipy = 4,4- Bipyridine, H4BTA = 1,2,4,5-Benzenetetracarboxylic Acid) were synthesized and characterized by single-crystal X-ray diffraction, powder diffraction, elemental analysis, IR, and thermogravimetric analysis. Both of complexes 1 and 2 are monoclinic crystal system, C2/c space group, and isostructural. The unit of the structure, the metal ion is coordinated by four water molecules and two bipy molecules, is a slightly distorted octahedral configuration, and the carboxyl group from BTA4− ion doesn’t coordinate with the metal ion, the H-bonding interactions further connect the mononuclear molecules to generate a 3D supramolecular complex.
Автор: Ling-Ling Gao, Yan Liu, Xu-Yan Lv, Jian-Feng Liu, and Tuo-Ping Hu 
Рік видання: 2012. Тип документу: Складова частина документу 
Розмір: 2,57 Мб     Кількість завантажень: 41

Synthesis and Spectroscopic Studies of Some New Molybdenum, Tungsten, and Ruthenium Carbonyl Derivatives of 2-Hydroxymethylpyridine

Thermal reactions of 2-hydroxymethylpyridine (HMP) with [M(CO)6] in air resulted in formation of the oxo-complexes [M2O6(HMP)2], where M = Mo, 1, or W, 2. The tricarbonyl complex [Ru(CO)3(HMP)], 3, was obtained from the reaction of [Ru3(CO)12] with HMP. In presence of triphenyl phosphine (PPh3), the reaction of HMP with Ru3(CO)12 gave [Ru(CO)2(HMP)(PPh3)], 4. All the complexes were characterized by elemental analysis, mass spectrometry, IR, and NMR spectroscopy. The thermal properties of the complexes were also investigated by thermogravimetry technique.
Автор: M. A. Taher, S. E. Jarelnabbi, B. E. Bayoumy, S. M. El-Medani and R.M. Ramadan 
Рік видання: 2010. Тип документу: Складова частина документу 
Розмір: 563 Кб     Кількість завантажень: 41

Kinetic andMechanistic Study of the Reduction of Chromium(VI) by Lactic Acid

The kinetics and mechanism of the reduction of chromium(VI) by lactic acid (Lac) in aqueous acidic medium was studied with spectrophotometry in a temperature range of 298.15 K∼313.15 K. Under the conditions of the pseudo-first order ([Lac]0
Автор: Jinhuan Shan, Fang Wang, Changying Song, and Heye Wang 
Рік видання: 2008. Тип документу: Складова частина документу 
Розмір: 665 Кб     Кількість завантажень: 41