Browsing by Author "Khoza, Sandile Humphrey"

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    Synthesis of Cobalt (II) Schiff Base Complexes: potential precursors for Cobalt and Cobalt Sulfide Nanoparticles
    (University of Zululand, 2017) Khoza, Sandile Humphrey
    Schiff bases ligands and their cobalt complexes have been widely studied due to their attractive chemical and physical properties, which enables exploitation in a multiplicity of applications in several scientific areas. Metal and metal sulfide nanoparticles are useful in many applications as they exhibit different particle sizes, shapes and surface-to-volume ratios. Several methods for the preparation of metal and metal sulfide nanoparticles have been established. In this project, cobalt and cobalt sulfide nanoparticles were selected and synthesized because of their unique properties and applications. The use of single source precursors for the synthesis of nanoparticles have been used by methods such as hot injection and pyrolysis. The synthesis of three Schiff base ligands namely; N,N'-bis(1-naphthaldehyde)-4-methylorthophenylenediimine [Ligand (1)], N,N'-bis(5-methoxybenzaldehyde)-4-methylorthophenylenediimine [Ligand (2)] and N-(naphthaldehyde)- N'-(3-methylbenzylidene)benzoic acid [Ligand (3)], leads to the formation of three Schiff base cobalt(II) complexes namely; N,N'-bis(1-naphthaldehyde)-4-methylorthophenylenediiminatocobalt(II) [Complex (4)]; N,N'-bis(5-methoxybenzaldehyde)-4-methylorthophenylenediiminatocobalt(II) [Complex (5)] and N-(naphthaldehyde)- N'-(3-methylbenzylidene)benzoic cobalt(II) [Complex (6)]. The complexes (4 and 5) were used as single source precursors (SSPs) for the fabrication of cobalt nanoparticles by the hot injection and the pyrolysis routes. For the fabrication of cobalt sulfide, only the hot injection route was used. The variation of parameters such as reaction time and temperature were used to determine their properties.The morphology, composition, structural and magnetic properties of the as-synthesized nanoparticles were found to depend on the reaction conditions used during the synthesis. The morphology and structural properties of the cobalt and cobalt sulfide nanoparticles were investigated using different techniques. Nanorods and cubic-like shaped Co nanoparticles which are indexed to a mixture of cobalt and cobalt oxide phases, were observed. Furthermore, the as-synthesized Co nanoparticles showed ferromagnetic behaviour. The use of 1-dodecanethiol as sulfur source afforded the formation of cobalt sulfide nanoparticles when complex (6) was used as single source precursor. The X-ray diffraction, high resolution transmission electron microscopy and selected area electron diffraction confirmed the formation of cubic Co9S8 and Co3S4 phase.