CHROMOTROPIC CHANGES OF Cu(II) AND Ni(II) COMPLEXES WITH N2O2 AND N3O2 SCHIFF-BASE LIGANDS IN THE SOLID PHASE

Modulation of synthetic parameters of cobalt nanoparticles: TEM, EDS, spectral and thermal studies

The study focuses on the modulation of synthetic parameters in order to influence the size, structure, composition and arrangement of nanoparticles of cobalt. Cobalt nanoparticles were synthesized by ethanolic solution of benzildiethylenetriamine in cobalt nitrate solution at 60 °C with stirring and refluxing leads to nanoparticles of cobalt. The morphology and structure of the synthesized nanoparticles of cobalt were characterized by Transmission Electron Microscopy (TEM), Powder X-ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), QELS Data and Infrared Spectroscopy (IR). Crystalline size was 20 nm determined from the sharp peak at 2θ=25 °C from the powder XRD. TEM images of cobalt nanoparticles without reducing agent having the diameter 20 nm with spherical shape and black color.

Co(II), Ce(III) and UO2VI) bis-salicylatothiosemicarbazide complexes: binary and ternary complexes, thermal studies and antimicrobial activity

A series of new metal complexes of Co(II), Ce(III) and UO(2)(VI), with the Schiff base ligand, H2L, bis-salicylatothiosemicarbazide have been prepared in presence of different molar ratios of LiOH.H2O as a deprotonating agent. Also, the ternary complexes were prepared by using 2-aminopyridine (2-Ampy) or oxalic acid (Ox) as a secondary ligand. All synthesized compounds were identified and confirmed by elemental analyses, molar conductivities, spectral (UV-Vis, IR, 1H NMR, mass) and magnetic moment measurements as well as TG-DSC technique. The changes in the selected vibrational absorption bands in IR and NMR spectra of the Schiff base ligand upon coordination indicate that, the ligand behaves as a neutral, monoanionic and/or dianionic tetradentate manner with ONNO donor sites. Conductance measurements suggest the non-electrolytic and 1:1 electrolytic nature of the metal complexes. Thermal studies suggest a mechanism for degradation of the metal complexes as function of temperature supporting the chelation modes, moreover, show the possibility of obtaining new complexes pyrolytically in the solid state which cannot be synthesized from solution. Antimicrobial screening of the free ligand and its binary complexes showed that, the free ligand and some metal complexes possess antimicrobial activities towards four type of bacteria and five types of fungi and these results were compared with eleven type of known antibiotics.