Complexation Of Cobalt Ions Research Articles

Cobalt separation from water and food samples based on penicillamine ionic liquid and dispersive liquid-liquid microextraction before determination by AT-FAAS

The cobalt compounds have adverse health effect on human and caused damage to the DNA cells, neurological and endocrine systems. Therefore, the separation and determination of cobalt in water and food samples must be considered. In this research, the (2S)-2-amino-3-methyl-3-sulfanylbutanoic acid (penicillamine) as a chelating agent mixed with ionic liquid (OMIM PF6) /acetone and used for extraction of cobalt from 50 mL of water samples by ultra-assisted dispersive liquid-liquid microextraction (USA-DLLME) at pH=6. Based on procedure, the samples were shaked for 5 min (25oC) and after complexation of cobalt ions by thiol and amine group of penicillamine, the ionic liquid phase separated in the bottom of the conical tube by centrifuging for 3.0 min. The upper liquid phase was vacuumed by the auto-sampler and the Co2+ ions back extracted from the ionic liquid/ penicillamine in acidic pH. Finally, the cobalt concentration in remained solution was determined by atom trap flame atomic absorption spectrometry (AT-FAAS). The main parameters such as the sample volume, the penicillamine amount, the ionic liquid amount and the shaking time were optimized. The linear range, the detection limit (LOD) and enrichment factor were obtained 1.5-62 μg L-1, 0.38 μg L-1 and 98.5, respectively (r = 0.9995, RSD%=2.2).

A Study and Optimization of Complexation of Cobalt Ions with Dihydroquercetin in Aqueous Solutions

This work continues a series of studies devoted to complex formation of ions of biogenic metals with the flavonoid dihydroquercetin (DHQ). The interaction of Со2+ ions with DHQ in aqueous solutions has been investigated. It has been found that, at different pH of a solution, complex compounds (CC) with different stoichiometry are formed; a variation of the pH value of a solution from 6.0 to 7.0 results in the formation of compounds (1)–(3) with the metal : flavonoid ligand ratio (Met : L) from 1 : 2 at рН 6.0 (1), through 2 : 3 at pH 6.4–6.7 (2), to 1 : 1 at рН 6.8–7.0 (3). By using the thermogravimetric method and the data of the elemental analysis, the most probable composition of the compounds with the determination of the amount of bound water has been proposed: [CoL2(H2O)4] for (1), [Co2L3(ОН)(H2O)4] for (2), and [CoL(ОН)(H2O)2] for (3). Conditions for the optimization of product yield in the complexation reaction of Со2+ ions with DHQ in an aqueous solution have been determined for compound (2): the рН value of solution 6.7; the reaction time 15 min; the temperature of the reaction solution 90°С; the molar ratio of the initial reagents DHQ : Со2+ 1 : 1.5; the initial concentration of DHQ 0.020 mol/L and that of Со2+ 0.030 mol/L; and the use of CoSO4 ⋅ 7H2O as a source of cobalt ions. The yield of the product is 81.8%.

Influence of Cobalt Ions on Collagen Gel Formation and Their Interaction with Osteoblasts

Metals on metal implants have long been used in arthroplasties because of their robustness and low dislocation rate. Several relatively low-corrosion metals have been used in arthroplasty, including 316L stainless steel, titanium, and cobalt–chromium–molybdenum alloy. Debris from these implants, however, has been found to cause inflammatory responses leading to unexpected failure rates approaching 10% 7 years surgery. Safety assessment of these materials traditionally relies on the use of simple two-dimensional assays, where cells are grown on the surface of the material over a relatively short time frame. It is now well-known that the composition and stiffness of the extracellular matrix (ECM) have a critical effect on cell function. In this work, we have evaluated how cobalt ions influence the assembly of type I collagen, the principle component of the ECM in bone. We found that cobalt had a significant effect on collagen matrix formation, and its presence results in local variations in collagen density. This increase in heterogeneity causes an increase in localized mechanical properties but a decrease in the bulk stiffness of the material. Moreover, when collagen matrices contained cobalt ions, there was a significant change in how the cells interacted with the collagen matrix. Fluorescence images and biological assays showed a decrease in cell proliferation and viability with an increase in cobalt concentration. We present evidence that the cobalt ion complex interacts with the hydroxyl group present in the carboxylic terminal of the collagen fibril, preventing crucial stabilizing bonds within collagen formation. This demonstrates that the currently accepted toxicity assays are poor predictors of the longer-term biological performance of a material.

Synthesis of sulfadimethoxine based surfactants and their evaluation as antitumor agents.

Synthesized CO (II) and Pt (II) of sulfadimethoxine. These compounds were tested for potential antitumor activity against two of human tumor cell lines, colon carcinoma cell line [Hct116], and breast carcinoma cell line MCF7. The structures of the resulting compounds have been investigated by elemental, FT-IR and H 1 NMR analyzes to insure the purity and confirmed the structures of them. The surface properties studies and octanol/water partition coefficients, Po/w were measured. The synthesized compounds exhibit biological activities with the lowest log Po/w and critical micelle concentration (CMC) values. In addition, in this article we provide an insight into this subject in order to increase the drug bioavailability. Inhibitory activity against colon carcinoma cells was detected for Pt and cobalt ion complex with IC50 = 4.5, 2.2 µg and against breast carcinoma cells IC50 = 18.2, 5.7 µg, respectively. The main goal of cancer therapy is to attain the maximum therapeutic damage of tumor cells in combination with a minimum concentration of the drug. This can be achieved in principle via selective antitumor preparations, the cytostatic effects of which would be restricted within tumor tissue. While 100% selectivity may be impractical, the achievement of reasonably high selectivity seems to be a feasible aim. Platinum and cobalt complex surfactants in our research affect tumor tissue at a very low concentration at values lower than their CMC values; this indicate that the sulfadimethoxine complexes merit further investigation as potential antitumor drugs.

Synthesis, spectroscopic characterization and antibacterial activity of new cobalt(II) complexes of unsymmetrical tetradentate (OSN 2) Schiff base ligands

Cobalt ion complexes with the Schiff bases, (4-X-2-{[2-(2-pyridine-2-yl-ethylsulfanyl)ethylimino]methyl}phenol (X = methoxy (OMe), phenylazo (N 2Ph), bromo (Br), nitro (NO 2)),were synthesized and investigated by several techniques using elemental analysis (C, H, N), FTIR, electronic spectra and molar conductivity. The thermal stability of free ligands and related cobalt complexes were studied by using differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). Cyclic voltammetry indicates that the investigated cobalt complexes, under the experimental conditions, have irreversible redox behavior. The synthesized compounds have antibacterial activity against the four Gram-positive bacteria: Streptococcus pyogenes, Streptococcus agalactiae, Staphylococcus aureus and Bacillus anthracis and also against the two Gram-negative bacteria: Klebsiella pneumoniae and Pseudomonas aeruginosa. The activity data show that the parent Schiff bases are more potent antibacterials than the cobalt complexes.

Effect of the Cobalt Ion and Polyethyleneimine Adsorption on the Surface Forces between Tungsten Oxide and Cobalt Oxide in Aqueous Media

We used the colloidal probe technique with atomic force microscopy to study the interactions between a tungsten oxide sphere, WO3, and flat oxidized tungsten and cobalt surfaces in aqueous electrolytes. We investigated the effects of adsorption of cobalt ions to tungsten oxide surfaces and adsorption of polyethyleneimine (PEI). Low concentrations of cobalt ions added to a WO3 system resulted in extended hydration forces and a lowering of the absolute value of the surface potential. PEI was shown to adsorb to the WO3 surfaces and induce an electrosteric repulsion in both the symmetric (WO3–WO3) and asymmetric (WO3–CoOOH) systems. The possible complexation of cobalt ions with PEI does not significantly influence the thickness of the adsorbed layer.

Complexation of cobalt ion with copolypeptide containing tryptophan treated with nitric acid

Tryptophan within copoly(N-hydroxyethyl L-giutamine-co -L-tryptophan) treated with nitric acid (EGT-N) dissociates negatively above pH 10.5 by the electron-attractive effect of nitro groups introduced into the indole ring. The interaction between EGT-N and various metal ions was investigated using UV/VIS, ESCA, and ICP measurement. EGT-N was found to selectively form a complex with cobalt ions above pH 10.5. The formation of the cobalt ion complex of EGT-N was confirmed to be caused by the cooperative coordination of the tryptophan-introduced nitro groups and the OH groups of hydroxyethyl L-glutamine.