Mohamed F. Eid

Synthesis, characterization and thermal studies of binary and/or mixed ligand complexes of Cd(II), Cu(II), Ni(II) and Co(III) based on 2-(Hydroxybenzylidene) thiosemicarbazone: DNA binding affinity of binary Cu(II) complex

A new series of metal complexes of Cd(II), Cu(II), Ni(II) and Co(III) with Schiff base ligand, H(2)L, 2-(Hydroxybenzylidene) thiosemicarbazone were synthesized. The mixed ligand complexes were prepared by using glycine (Gly), 2-aminopyridine (2-Ampy) and 1,10-phenanthroline (Phen) as secondary ligands. The structure of these complexes was identified and confirmed by elemental analysis, molar conductivity, UV-Vis, FT-IR and (1)H NMR spectroscopy and magnetic moment measurements as well as TG-DSC technique. The discussions of the prepared complexes indicate that the ligand behaves as a monoanionic tridentate ligand through ONS donor sites. Thermal studies suggested a mechanism for the degradation of the metal complexes as a function of temperature supporting the chelation modes and showed the possibility of obtaining new complexes pyrolytically in the solid state which cannot be synthesized from the solution. The absorption studies support that the binary Cu(II) complex exhibits a significant binding affinity to HS-DNA through intercalative mode.

Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex.

A Tetraaza Macrocylic Ligand (H2L) and its complexes, [Cd(H2L)(OH2)2](NO3)(2)·1/2OH2 (I), [Co(H2L)(OH2)](NO3)(2)·1/2OH2 (II), [Cu(H2L)(NO3)2]·3/2OH2 (III) and [Ni(H2L)(NO3)(OH2)]NO3·OH2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH2)2] (V), [CoL(OH2)2] (VI), [CuL(OH2)2] (VII) and [Ni(H2L)(NO3)2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H2L and its copper complex (III) can bind to DNA through an intercalative mode. The H2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.

Thermodynamic parameters of lanthanoid(III) complexation with 3-(α,δ-dicarboxy-n-propylidenehydrazino)-5,6-diphenyl-1,2,4-triazine(DCPT). part 2

Abstract The complex formation equilibria between lanthanoid(III) and DCPT ions have been studied by potentiometry in 75% (v/v) dioxane-water mixture and 0.10M KNO 3 as constant ionic medium, at 10, 20, 30 and 40°C. A series of mononuclear protic [Ln(HL)] 2+ , [Ln(HL) 2 ] + , [Ln(HL) 3 ], [LnL(HL) 2 ] − , [LnL 2 (HL)] 2− and non-protic [LnL 3 ] 3− complex species were found in solutions and their formation constants, ethalpies and entropies were determined. It was established that the stepwise Gibbs energies of the protonated complexes varied in the sequence − ΔG Ln(HL) > − ΔG Ln(HL) 2 > − ΔG Ln(HL) 3 , and the stepwise enthalpies the order was − ΔH Ln(HL) > − ΔH Ln(HL) 2 > − ΔH Ln(HL) 3 , and the entropy markedly increased in the order ΔS Ln(HL) > ΔS Ln(HL) 2 > ΔS Ln(HL) 3 . The results are discussed in relation to changes in the metal-water and metal-ligand bond strength. The variation of the thermodynamic parameters as a function of ionic potential of lanthanide elements is discussed in terms of the different hydration numbers of lighter and heavier lanthanide(III) ions.

Thermodynamic and spectrophotometric studies of acetoacetanilidehydrazone complexes of Cu(II), Ni(II) and Co(II) metal ions

Abstract Complexes of o -carboxyphenylhydrazoneacetoacetanilide ( o -CPHAA) with Cu(II), Ni(II) and Co(II) were studied in dioxane-water using the Irving and Rossotti method over the temperature range 10–40 °C and at constant ionic strength (0.1 M). The acid dissociation constant p K H 1,2 of the ligand and the stepwise stability constants (log K 1 and log K 2 ) of the complexes formed were computed at various temperatures. The values of the stepwise and overall changes in Δ G , Δ H and Δ S accompanying the neutralization of the ligand and complex formation were evaluated. This study reveals that the ionization of the ligand in the mixed solvent is an endothermic process, whereas the complex formation is an exothermic reaction. The optimum conditions for complex formation and the composition and stability constants (log K 1 ) of the complexes formed in solution between the ligand and Cu(II), Ni(II) and Co(II) were also determined (spectrophotometrically).

The complexation of a novel squaric bis(thiosemicarbazone); 3,4-bis{[(aminothioxomethyl)amino]azamethylene}cyclobut-ene-1,2-diol

A novel chelating agent (Sqtsc; H(4)L) bearing both hard and soft donor atoms was synthesized by the condensation of squaric acid with thiosemicarbazide. The ligand has two symmetrical sets of donor atoms (SNO), therefore, it was allowed to react with the metal ions at the mole ratio 2:1 (M:L). Mono- and bi-nuclear chelates were obtained in which the ligand showed a variety of modes of bonding viz. (OO)(2-), (SNNS)(2-) and (SNO)(2-) per each metal ion supporting the ambidentate and flexidentate characters of the ligand. The mode of bonding and basicity of the ligand depend mainly on the type of the metal cation and its counter anion. All the obtained complexes have the preferable O(h)-geometry except the VO(II)-complex (7) which has also the preferable square pyramid geometry. Structural elucidation was achieved via elemental and spectral data.