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Synthesis, Characterisation and Application of Iron Nanoparticles from Organometallic Precursors

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dc.contributor.advisor Tilley, Richard
dc.contributor.author Herman, David Alan John
dc.date.accessioned 2013-06-03T23:19:49Z
dc.date.accessioned 2022-11-02T20:23:51Z
dc.date.available 2013-06-03T23:19:49Z
dc.date.available 2022-11-02T20:23:51Z
dc.date.copyright 2013
dc.date.issued 2013
dc.identifier.uri https://ir.wgtn.ac.nz/handle/123456789/28988
dc.description.abstract Magnetic nanomaterials are actively researched due to their size and shape dependent magnetisation. Of particular interest are iron-based nanomaterials which are currently widely investigated as potential magnetic resonance imaging contrast agents, drug delivery vehicles, and as theranostic agents. This thesis is concerned with the solution phase synthesis of iron/iron oxide core-shell nanoparticles via the hot-injection of iron containing organometallic precursors at various reaction temperatures. Solution synthesis allows for precise control over nanoparticle synthesis utilising changes in reaction temperature, capping agents and reaction time to favour a discrete nanoparticle size or shape. It was observed that the nanoparticle size could be controlled by careful choice of the iron precursor and reaction temperature. The nanoparticle morphology, crystallinity, and chemical composition were studied by transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The magnetic properties of the nanoparticles where characterised using the superconducting quantum interference device (SQUID) and magnetic resonance imaging (MRI). Chapters 1 and 2 provide an introduction to the background for this thesis, including an extensive literature review on the current state of iron nanoparticle synthesis, and the experimental methods used in this research. The two main synthetic strategies employed were bench-top method and Fischer-Porter bottle method. In Chapter 3, iron/iron oxide core-shell nanoparticles were synthesised from the precursor (η5-cyclopentadienyl)(η5-cyclohexadienyl)iron(II), [Fe(η5-C5H5)(η5-C6H7)], at reaction temperatures ≤ 200°C. [Fe(η5-C5H5)(η5-C6H7)] has successfully been used to synthesise iron nanoparticles in the Fischer-Porter bottle, however remained to be examined via the bench-top method. The lack of size and shape control of the nanoparticles synthesised, regardless of altering the reaction temperature, capping agent or reaction time was proposed to be due to having insufficient thermal energy at reaction temperatures of ≤ 200°C to induce a rapid nucleation burst. In Chapter 4, the reaction temperature was increased to 300°C, and [Fe(η5-C5H5)(η5-C6H7)] along with other organometallic precursors were investigated. It was found that at high reaction temperatures, the asymmetry of [Fe(η5-C5H5)(η5-C6H7)] was resulting in a complex decomposition pathway, and the insufficient separation of nucleation and growth stages as the reaction proceeded. Subsequent decomposition of precursors reported in literature yielded monodisperse nanoparticles, and the decomposition of ferrocene and bis(indenyl)iron(II) resulted in both large and small monodisperse iron/iron oxide core-shell nanoparticles respectively. It was concluded that organometallic iron sandwich compounds that had identical ligands resulted in monodisperse nanoparticles due to a more uniform decomposition, and the final size was linked to the stability of the precursor. In Chapter 5, the synthesis of various pseudoferrocene compounds were investigated as potential iron precursors. The pseudoferrocene compound bis(η5-1,3,5-exo-6-tetramethylcyclohexadienyl) iron(II), [Fe(η5-C6H3Me4)2], was found to be the most suitable precursor for the hot-injection synthesis of 14-16 nm iron nanoparticles due to its relative stability, symmetry and ease of synthesis. The successful synthesis of monodisperse 14 nm iron/iron oxide core-shell nanoparticles in the Fischer-Porter bottle was also achieved. In Chapter 6, the formation of nanoparticles from [Fe(η5-C6H3Me4)2] was investigated. It was found that the growth temperature had to be finely controlled to ensure no secondary burst nucleation events occurred, resulting in nanoparticle polydispersity. The nanoparticle formation over time was monitored, with the formation of the coreshell structure observed, with fast growth the α-Fe core occurring early on in the reaction. The final nanoparticles had a high magnetic saturation of 148 emu.g-1(Fe), and was proven to be an optimal T2 contrast enhancers for MRI imaging with a relaxivity of 332 mM-1.s-1, three times that for iron oxide nanoparticles. Finally, Chapter 7 provides the overall conclusions of this research, and the future plans for this work. In particular the chapter discusses the key variables required for the formation of monodisperse iron/iron oxide core-shell nanoparticles from organometallic sandwich compounds with a focus on the precursor structure and growth temperature. en_NZ
dc.format pdf en_NZ
dc.language en_NZ
dc.language.iso en_NZ
dc.publisher Te Herenga Waka—Victoria University of Wellington en_NZ
dc.rights Access is restricted to staff and students only. For information please contact the library en_NZ
dc.subject Nanoparticles en_NZ
dc.subject Iron en_NZ
dc.subject Synthesis en_NZ
dc.title Synthesis, Characterisation and Application of Iron Nanoparticles from Organometallic Precursors en_NZ
dc.type Text en_NZ
vuwschema.contributor.unit School of Chemical and Physical Sciences en_NZ
vuwschema.subject.marsden 250201 Transition Metal Chemistry en_NZ
vuwschema.subject.marsden 250103 Colloid and Surface Chemistry en_NZ
vuwschema.subject.marsden 259901 Organometallic Chemistry en_NZ
vuwschema.type.vuw Awarded Doctoral Thesis en_NZ
thesis.degree.discipline Chemistry en_NZ
thesis.degree.grantor Te Herenga Waka—Victoria University of Wellington en_NZ
thesis.degree.level Doctoral en_NZ
thesis.degree.name Doctor of Philosophy en_NZ

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