S. L. Stefan

Bio: S. L. Stefan is an academic researcher from Ain Shams University. The author has contributed to research in topics: Thermal decomposition & Metal ions in aqueous solution. The author has an hindex of 1, co-authored 1 publications receiving 15 citations.

Thermal decomposition of some metal chelates of substituted hydrazopyrazolones

Abstract: The thermal dissociation of 1-phenyl-3-methyl-4-(X-phenylhydrazo)-5-pyrazolone metal chelates [M(XPhHyPy)](X=m-OH (I),m-OCH3(II),m-COOH (III),p-CH3 (IV),p-OCH3 (V) orp-COCH3 (VI) was studied by TG, DTG and differential thermal analysis (DTA). A rough sequence of thermal stability, obtained from the peak maximum temperatures, for the various metal chelates was Hg(II)

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

Abstract: New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method.

Studies on Some Schiff Base Complexes of CoII, NiII and CuII Derived from Salicylaldehyde and O-Nitrobenzaldehyde

Abstract: Schiff bases of the type salicylidene 2-aminobenzothiazole and o-nitrobenzylidene 2-aminobenzothiazole were prepared by condensation of 2-aminobenzothiazole with salicylaldehyde and o-nitrobenzaldehyde. The bases react with cobalt(II), nickel(II) and copper(II) chlorides to give 1:1 and 1:2 complexes. Electronic spectra, magnetic susceptibility measurements and infrared data are used to infer the structures. The thermal decomposition of the complexes and evaluation of the thermodynamic parameters are also reported.

Thermodynamics of substituted pyrazolone. V: Potentiometric and conductometric studies of complexes of some transition metals with 4-(4-acetophenyl)hydrazono-3-methyl-2- pyrazolin-5-one

Abstract: Proton-ligand dissociation constants of 4-(4-acetophenyl)hydrazono-3-methyl-2-pyrazolin-5-one (AHMP) and metal-ligand stability constants of its complexes with some transition metal ions were calcu...

In vitro anti-leishmanial and anti-fungal effects of new SbIII carboxylates

Abstract: Ring opening of phthalic anhydride has been carried out in acetic acid with glycine, β-alanine, L-phenylalanine, and 4-aminobenzoic acid to yield, respectively, 2-{[(carboxymethyl)amino]carbonyl}benzoic acid (I), 2-{[(2-carboxyethyl)amino]carbonyl}benzoic acid (II), 2-{[(1-carboxy-2-phenylethyl)amino]carbonyl}benzoic acid (III), and 2-[(4-carboxyanilino)carbonyl]benzoic acid (IV). Compounds I-IV have been employed as ligands for Sb(III) center (complexes V-VIII) in aqueous medium. FTIR and 1H NMR spectra proved the deprotonation of carboxylic protons and coordination of imine group and thereby tridentate behaviour of the ligands as chelates. Elemental, MS, and TGA analytic data confirmed the structural hypothesis based on spectroscopic results. All the compounds have been assayed in vitro for anti-leishmanial and anti-fungal activities against five leishmanial strains L. major (JISH118), L. major (MHOM/PK/88/DESTO), L. tropica (K27), L. infantum (LEM3437), L. mex mex (LV4), and L. donovani (H43); and Aspergillus Flavus, Aspergillus Fumigants, Aspergillus Niger, and Fusarium Solani. Compound VII exhibited good anti-leishmanial as well as anti-fungal impacts comparable to reference drugs.