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Metallation of tetradentate N2O2 Schiff base with Mn(II), Co(II), Cu(II) and Zn(II): synthesis, characterization and formation constants measurement

100%

Asadi M., Mohammadikish M., Mohammadi K.

Open Chemistry

2010

vol. 8

issue 2

291-299

Four Schiff base ligands, salabza-H2 = N,N′-bis(salicylidene)-2-aminobenzylamine, were synthesized by condensation of one mole of 2-aminobenzylamine and two moles of salicylaldehyde and/or two moles of substituted salicylaldehyde (5-OMe, 5-Br, 5-NO2). All the four Schiff bases and their Mn(II), Co(II), Cu(II) and Zn(II) complexes are characterized by UV-Vis, FT-IR, 1H NMR spectroscopy, mass spectrometry and elemental analysis. The formation constants and the Gibbs free energies were measured spectrophotometrically for 1:1 complexes in methanol in constant ionic strength (I = 0.1 mol dm−3 NaClO4) and at 25°C. The data refinement was carried out with the SQUAD program. The trend of formation constants of H2L1 with M(II) follows the order: Mn(II) (3.97) Also, the trend of formation constants of ligand toward a given metal (for example Mn) is as follows: H2L1 (p-OMe) (3.97) > H2L2 (p-H) (3.65) > H2L3 (p-Br) (3.37) > H2L4 (p-NO2) (3.04) [...]

Studies on complex formation between curcumin and Hg(II) ion by spectrophotometric method: A new approach to overcome peak overlap

88%

Waranyoupalin R., Wongnawa S., Wongnawa M., Pakawatchai C., Panichayupakaranant P., Sherdshoopongse P.

Open Chemistry

2009

vol. 7

issue 3

388-394

Complex formation between curcumin and Hg(II) ion MeOH/H2O (1: 1 v/v) was investigated and monitored by the spectrophotometric method. The absorption peak of unreacted curcumin which was close and overlapped with that of the complex, was removed by calculation using Microsoft Excel, thereby, allowing determination of the stoichiometry of the complex by the mole-ratio and the Job’s continuous variation methods. Both methods indicated that a 1:1 complex of curcumin and Hg(II) was formed in solution. The formation constant of the 1:1 Hg(II) complex was obtained from two methods, the equilibrium concentration calculation and the linear plot of Benesi-Hildebrand equation, as log K = 4.44 ± 0.16 and 4.83 ± 0.02, respectively. The structure is proposed as a tetrahedral complex of Hg(II) with one curcumin and two chloride ions as ligands. [...]

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2 Open Chemistry

1 2010

1 2009

1 Asadi M.

1 Mohammadi K.

1 Mohammadikish M.

1 Pakawatchai C.

1 Panichayupakaranant P.

1 Sherdshoopongse P.

1 Waranyoupalin R.

1 Wongnawa M.

1 Wongnawa S.

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Metallation of tetradentate N2O2 Schiff base with Mn(II), Co(II), Cu(II) and Zn(II): synthesis, characterization and formation constants measurement

Studies on complex formation between curcumin and Hg(II) ion by spectrophotometric method: A new approach to overcome peak overlap