• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.667-670
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• 2003

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.189-198
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• 2011

In the present paper two new thiosemicarbazones i.e., 4[N-(4'-ethylbenzalidene)amino]antipyrine thiosemicarbazone (EBAAPTS) and 4[N-(2',4'-dimethylbenzalidene)amino]antipyrine thiosemicarbazone (DMBAAPTS) have been synthesized and characterized. The complexing abilities of these thiosemicarbazones i.e. EBAAPTS and DMBAAPTS towards cobalt(II) and nickel(II) salts have been explored. The reactions of the hot ethanolic solutions of cobalt(II) and nickel(II) salts with EBAAPTS and DMBAAPTS led to the formation of the novel complexes of general composition [$MX_2(L)H_2O$] (M=$Co^{2+}$ or $Ni^{2+}$; X=$Cl^-$, $Br^-$, $NO_3^-$, $NCS^-$ or $CH_3COO^-$; L=EBAAPTS or DMBAAPTS). The newly synthesized complexes have been characterized by elemental analyses, molar mass, molar conductance, magnetic susceptibility, infrared and electronic spectral studies. The molar conductance measurements of the complexes in nitrobenzene correspond to their non-electrolytic nature. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry has been assigned for Co(II) and Ni(II) complexes of the type [$MX_2(L)H_2O$]. These complexes were screened for their antibacterial and antifungal activities on different species of pathogens, fungi and bacteria and their biopotency has been discussed.

• Journal of the Korean Chemical Society
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• v.53 no.1
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• pp.17-26
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• 2009

Hydrazones of isonicotinic acid hydrazide, viz., N-isonicotinamido-furfuralaldimine (INH-FFL), N-isonicotnamido-cinnamalidine (INH-CIN) and N-isonicotnamido-3',4',5'-trimethoxybenzaldimine (INH-TMB) were prepared by reacting isonicotinic acid hydrazide with respective aromatic aldehydes, i.e., furfural, cinnamaldehyde or 3,4,5-trimethoxy-benzaldehyde. A new series of fifteen complexes of cobalt(II) with these new hydrazones, INH-FFL, INH-CIN and INH-TMB, were synthesized by their reaction with cobalt(II) salts. The infrared spectral data reveal that hydrazone ligands behave as a bidentate ligand with N, O donor sequence towards the $Co^{2+}$ ion. The complexes were characterized on the basis of elemental analysis, magnetic susceptibility, conductivity, infrared and electronic spectral measurements. Analytical data reveal that the complexes have general composition [Co($L)_2X_2]\;and\;[Co(L)_3](ClO_4)_2$ where L= INH-FFL, INH-CIN or INH-TMB and X = $Cl^-,{NO_3}-,\;NCS^-\;or\;CH_3COO^-.$ The thermal behaviour of the complexes were studied using thermogravimetrictechnique. Electronic spectral results and magnetic susceptibility measurements are consistent with the adoption of a six-coordinate geometry for the cobalt(II) chelates. The antimicrobial properties of cobalt(II) complexes and few standard drugs have revealed that the complexes have very moderate antibacterial activities.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.341-345
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• 2011

The Schiff base cobalt(II) complex, bis[4-chloro-2-((E)-(isopropylimino) methyl) phenol]cobalt(II), has been prepared and characterized by single-crystal X-ray diffraction analyses. The phenomenological, kinetic and mechanistic aspects of the cobalt (II) complex have been studied by TG/DTG techniques. On the basis of the experimental data, the kinetic parameters such as activation energy, pre-exponential factor and entropy of activation were computed, and then the most probable mechanism function was estimated as $g({\alpha})={\alpha}^2$ 2. Hence the rate controlling process at all stages of decomposition is onedimensional diffusion (Parabolic model).

• Journal of the Korean Chemical Society
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• v.22 no.3
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• pp.133-137
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• 1978

A straight chain flexible tetraamine ligand, 1,l0-dipropyl-5R-methyltriethylenetetraamine(R-$Pr_2$metrien) has been synthesized, and the dichloro and dinitro cobalt(III) complexes of this ligand have been prepared. The ligand has been expected to show a topological preference for the trans isomer. As expected, only trans geometrical isomers have been obtained and their structures have been elucidated via elemental analyses, nmr, electronic absorption and CD data.

• Resources Recycling
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• v.19 no.4
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• pp.29-34
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• 2010

Distribution diagram of $CoCl_2$ and $MnCl_2$ was obtained by analyzing ionic equilibria of the two metals in HCl solution. In the HCl concentration range of 4 and 10 M, most of cobalt exists as $CoCl_2$, whereas Mn exists $MnCl_{3}^-$ and $MnCl_2$. Extraction isotherm of Co(II) and Mn(II) was calculated by using the equilibrium constant for the solvent extraction of the two metals by Alamine336. Although the equilibrium constant for the solvent extraction of Mn was higher than that of Co, extraction isotherm indicated that cobalt could be extracted more efficiently than manganese at the same initial extraction conditions.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.331-338
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• 2007

A rapid, simple and sensitive spectrophotometric method was developed for the determination of cobalt(II) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a analytical reagent. The metal ion in aqueous medium forms a brown coloured complex with HMBATSC at pH 6.0. The complex has two absorption maxima at 375 nm and 390 nm. At 375 nm, the reagent shows considerable absorbance, while at 390 nm the reagent does not shows appreciable absorbance. Hence, analytical studies were carried out at 390 nm. Beer's law is obeyed in the range of 0.059-2.357 μg ml-1 of Co(II). The molar absorptivity and Sandall's sensitivity of the method are 2.74×104 l mol-1 cm-1 and 0.0024 μg cm-2 respectively. The interference of various diverse ions has been studied. The complex has 1:2 [Co(II)- HMBATSC] stoichiometry. A method for the determination of cobalt(II) by second order derivative spectrophotometry has also been proposed. The proposed methods were applied for the determination of cobalt(II) in alloy steels, vitamin B12 and in some biological samples.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.121-128
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• 1980

Isonitrosobenzoylacetone is particularly interesting, as the isonitroso group has two potentially coordinating sites which can compete with the cabonyl groups in forming bonds with the metal ions. In this paper tris(isonitrosobenzoylacetonato)cobalt(III) and bis(isonitrosobenzoylacetonato)palladium(II) have been prepared, and their structures have been investigated. Spectroscopic studies lead to the conclusion that the both complexes do not contain an OH group in the chelated five-membered ring structure in which the ligand coordinates to metal through oxygen of the acetyl group and nitrogen of the isonitroso group. The coordination manner of this ligand is similar to that of isonitrosobenzoylacetone obtained by Patel and Haldar.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.463-467
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• 1975

The polymerization of methyl methacrylate(MMA) initiated by cobalt (II) nitrate in tetrahydrofuran (THF) has been studied. From the results of kinetic studies, the overall polymerization rate (Rp) could be expressed as following; $R_p=k\;[cobalt(Ⅱ)\;nitrate]^{0.5}\;[MMA]^{1.5}$ By considering the effects of chelating agent on the polymerization rate, it could be assumed that the monomer, MMA might form a coordination complex with cobalt(II) nitrate. In the presence of radical inhibitor hydroquinone, the inhibition time was observed. And the apparent overall activation energy was calculated to be 14.0 kcal/mole.

• Analytical Science and Technology
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• v.6 no.1
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• pp.57-63
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• 1993

Spectrophotometric determination of cobalt by flow injection method is described. 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino) aniline rapidly forms a water-soluble complex with cobalt in $NH_3-NH_4Cl$ buffer solution at pH 10.5. The absorption maxima of this complex is at 545 nm with molar absorptivity of $58000L\;mol^{-1}\;cm^{-1}$. The calibration curve of cobalt is linear over the range of 0.1 to 0.6ppm and the detection limit is 25ppb. The relative standard deviation is ${\pm}0.72%$ for 0.5ppm and the sampling rate is $60samples\;hr^{-1}$. The interfering effect of some cations and anions was investigated. Ni(II), Cu(II), Fe(III) and $CN^-$ interfered severely. The interfering effect of these matallic ions could be decreased by adding $1.0{\times}10^{-3}M$ EDTA solution to the carrier stream.