Juan Camus

Synthesis, characterization and antibacterial activity of a Schiff base derived from cephalexin and sulphathiazole and its transition metal complexes.

Metal(II) coordination compounds of a cephalexin Schiff base (HL) derived from the condensation of cephalexin antibiotic with sulphathiazole were synthesized. The Schiff base ligand, mononuclear [ML(OAc)(H2O)2] (M(II)=Mn, Co, Ni, Zn) complexes and magnetically diluted trinuclear copper(II) complex [Cu3L(OH)5] were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The analytical and molar conductance values indicated that the acetate ions coordinate to the metal ions. The Schiff base ligand HL behaves as a monoanionic tridentate NNO and tetradentate NNOO chelating agent in the mono and trinuclear complexes respectively.

Manganese(II) and palladium(II) complexes containing a new macrocyclic Schiff base ligand: antibacterial properties

Complexes of tetradentate macrocyclic Schiff base ligand, L, with MnII and PdII ions have been synthesized by the template condensation of 1,10-phenanthroline-2, 9-dicarboxaldehyde, 2,3-diamino-1,4-naphthoquinone and 1,2-dibromoethane in EtOH. The complexes were characterized by physicochemical and spectroscopic methods and an octahedral geometry is suggested for their structure. They have been screened for antibacterial activity against several bacteria, and the results are compared with the activity of penicillin.

Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes

Metal(II) coordination compounds of a cephalothin Schiff base (H2L) derived from the condensation of cephalothin antibiotic with sulfadiazine were synthesized. The Schiff base ligand, mononuclear [ML(H2O)3] (M(II)=Mn,Co,Ni,Zn) complexes and magnetically diluted dinuclear copper(II) complex [CuL(H2O)3]2 were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The cephalothin Schiff base ligand H2L behaves as a dianionic tridentate NOO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method.

Tetradentate metal complexes derived from cephalexin and 2,6-diacetylpyridine bis(hydrazone): Synthesis, characterization and antibacterial activity.

Metal(II) coordination compounds of a hydrazone ligand (HL) derived from the condensation of cephalexin antibiotic with 2,6-diacetylpyridine bis(hydrazone) were synthesized. The hydrazone ligand and mononuclear [ML(H2O)2][PF6] (M(II)=Mn, Co, Ni, Zn) complexes were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The cephalexin 2,6-diacetylpyridine bis(hydrazone) ligand HL behaves as a monoanionic tetradentate NNNO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method.

ZINC(II), CADMIUM(II), MERCURY(II) AND LEAD(II) SEMIQUINONE-TYPE COMPLEXES OF A NEW SCHIFF-BASE LIGAND: ANTIBACTERIAL STUDIES

Abstract A new Schiff-base ligand LH2, has been prepared by reaction of 2,9-diformv 1-1,10-phenan-throline with 2,3-diamino-l,4-naphthoquinone. The formation and characterization of complexes of Zn(II), Cd(II), Hg(II) and Pb(II) with the semi-oxidized ligand LH is described. The M(LH)X2 (X = CI, Br and AcO) radical species are paramagnetic and the observed EPR signals in the solid state at room temperature, with g values close to the electron free g value are proof of the semiquinonic character of the ligand. The antibacterial activity of the ligand and the metal complexes prepared were tested against four bacteria strains and compared with the activity of penicillin.

EPR spectra of copper complexes with quinoxalinic and naphthoquinonic ligands

Abstract The electron paramagnetic resonance EPR spectra of a number of copper complexes with six quinoxalinic and naphthoquinonic ligands were measured in DMF solution and as crystalline powders both of which exhibited spectra with very sharp lines. The following ligands were investigated: 2,3-dihydroxyquinoxaline, 6-nitro-2,3-dihydroxyquinoxaline, 6,7-dinitro-2,3-dihydroxyquinoxaline, 2-hydroxy-3-mercaptomethyl-1,4-naphthoquinone, 2-amino-3-mercaptomethyl-1,4-naphthoquinone and 2,3-diamino-1,4-naphthoquinone. A complete analysis of the spectra was made and the covalence parameter α and the isotropic and anisotropic g values were obtained. The covalence parameters of the copper complexes of quinoxalinic ligands are high indicating an appreciable ionic character of the metal-ligand bond, whilst the amino derivatives of the naphthoquinonic complexes show low values indicating a markedly covalent metal-ligand bond.

Spectroscopic and electrochemical studies of NiII, CuII, PdII and VOII complexes with naphthoquinonic ligands

Abstract The electron transfer complexes of general type [M(L 1 ) 2 ], [M(L 2 ) 2 ] and [M(L 3 ) 2 ] with M = Ni II , Cu II , Pd II and VO II ions have been investigated using 2-hydroxy-3-methylmercaptan-1,4-naphthoquinone (HL 1 ), 2-amino-3-methylmercaptan-1,4-naphthoquinone (HL 2 ) and 2, 3-diamino-1,4-naphthoquinone (HL 3 ) as ligands. Polarographic results confirmed that some the these neutral compounds underwent reversible or quasi-reversible one-electron reduction processes, and the reduction potentials for the [M(L 1 ) 2 ] and [M(L 3 ) 2 ] complexes were lower than those of the corresponding [M(L 2 ) 2 ] complexes. EPR spectra of the prepared compounds, except the [Pd(L 2 ) 2 ] complex, show that they are paramagnetic and some of them behave as free radicals stabilized through the cation. An attempt to correlate spectroscopic and redox parameters has been made.