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devices [ 1 ]. Most of them show antiviral and antibacterial activity [ 2 ] and also used as mimic system for enzyme models [ 3 ]. Acyclic polydentate ligands are important member of chelating ligands which were used in coordination chemistry for their

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– 16 ] and nonlinear optical (NLO) [ 17 ], and materials chemistry by coordination chemists at all times [ 18 – 22 ]. Due to such a wide range of applications, new series of polydentate complexes of Pt(II), Cu(II), and Ni(II) are of particular

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Abstract  

Polydentate neutral organophosphorus compounds attract great interest as efficient extractants of transplutonium elements(TPE) from acid waste nuclear fuel element solution. With the view of a further search, reagents R′R″-PO-CH2-CNO-R 2 ″' were synthetized and investigated. The solubility of R 2 POCH2CNOR 2 ″' vas investigated in organic solvents and in nitric acid solutions. This reagent was found to be the best one.

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Abstract  

Ligand exchange is one of the possible synthetic routes to obtain99mTc coordination compounds. However, the success of this route depends on the availability of good precursors. The objective of this work is the preparation of the complex [99mTc(tu)6]3+ (tu = thiourea), as a potential precursor for99mTc(III) coordination compounds. The preparation was successfully performed in acidic conditions, the excess of tu serving as reducing agent. At pH values higher than 3, the compound becomes unstable and on addition of polydentate ligands new Tc(III) complexes are formed. With edta, the complex99mTc(III)-edta was obtained in high yield.

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Abstract  

Schiff bases obtained by the condensation of 2-amino-5-mercapto-1,3,4-thiadiazole with 2,4-pentandione or 1-phenyl-1,3-butandione were synthesized and characterized in order to obtain polydentate ligands HL1 and HL2, respectively. The complexes with these ligands of the type M(L)Cl·nH2O [(1) M:Ni, L:L1, n = 0.5; (3) M:Ni, L:L2, n = 0.5]; [(2) M:Cu, L:L1, n = 1; (4) M:Cu, L:L2, n = 0] were also synthesized and characterized. The modifications evidenced in IR spectra of complexes were correlated with the presence of monodeprotonate Schiff bases. The electronic spectra display the characteristic pattern of square-planar stereochemistry. The in vitro qualitative and quantitative antimicrobial activity assays showed that the new complexes exhibited variable antimicrobial activity. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. Schiff bases and complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion removal as well as oxidative degradation of the organic ligands were observed.

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Abstract  

A sequential leaching experiment for chemical speciation of particulate uranium in seawater was carried out using solution chemistry techniques. Mass action analysis on the leaching processes reveals that the major species of particulate uranium in seawater is an organic complex of uranium(VI), which is dissociated completely in the leaching solution of pH 1.0. Inert uranium, which is not dissolved in the leaching solution of pH 1.0, exists is suspended matter although it is a minor constituent. The result suggests that this species in an organic complex of uranium(IV). The analysis of the experimenmt deduces that an organic binding site in suspended matter reacts as a polydentate ligand, which has more than two stepwise protonation constants within the pH range of 2.0 to 8.2. The conditiona stability constant of the organic uranium complex in suspended matter under the conditions of seawater is within the following range: 12<log Kc,U<16. These findings suggest stronglt that the organic binding site in suspended matter can form stable chelates with metallic elements.

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A calculation method previously used in the study of simple ion pairs is extended in the present work to the entropies of formation of copper(II) and zinc(II) complexes with polydentate ligands in aqueous solution. Not only a qualitative, but also a quantitative and more significant discussion of the entropy data seems possible by this method. In particular, if the literature entropy data for copper(II) complexes with some carboxylic ligands and for zinc(II) with polyamines are used, the change from 6 to 4 in the coordination number of the cation is demonstrated, in accordance with previous suggestions. In the complex(Zntren)2+, the metal shows a coordination number of 5, in agreement with previous X-ray results.

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Introduction Interesting topics are provided in the field of coordination chemistry of polydentate amines and pyridines towards metal ions as a result of a wide range of applications of their complexes to prepare recognition

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Thermoanalytical studies of imidazole-substituted coordination compounds

Mn(II)-complexes of bis(1-methylimidazol-2-yl)ketone

Journal of Thermal Analysis and Calorimetry
Authors: S. Materazzi, S. Vecchio, L. W. Wo, and Curtis S. De Angelis

economically and ecologically relevant. The use of catalytically active transition metal complexes, which can activate hydrogen peroxide, might be a means of achieving these aims. Several manganese complexes with polydentate N-donor ligands have been

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Journal of Thermal Analysis and Calorimetry
Authors: Li-Fang Song, Chun-Hong Jiang, Cheng-Li Jiao, Jian Zhang, Li-Xian Sun, Fen Xu, Qing-Zhu Jiao, Yong-Heng Xing, Yong Du, Zhong Cao, and Feng-Lei Huang

.1021/la800555x . 5. Contreras , R , Flores-Parra , A , Mijangos , E , Tellez , F , Lopez-Sandoval , H , Barba-Behrens , N 2009 From mono to polydentate azole and benzazole

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