Chemistry - Masters by Research Theses

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    Computational analysis and partialsynthesis of resolvin analogues
    (University College Cork, 2022-06-02) Daly, Kevin; O'Sullivan, Tim; Irish Research Council
    An introduction to the role of resolvins in inflammation is outlined in Chapter 1. In addition, a literature survey of the structure-activity relationships of resolvins, protectins and maresins is also included. Chapter 2 briefly outlines the aims and objectives of this project. Chapter 3 focuses on the computational analysis of the outlined virtual library of Resolvin D2 analogues. The key physicochemical properties of each candidate are calculated and unsuitable candidates are eliminated using standard screening protocols. Chapter 4 describes the attempted synthesis of a key intermediate for the preparation of an aromatic resolvin analogue. This attempted synthesis encompasses a monosilylation of a diol, a selective oxidation of an alcohol to an aldehyde, a Wittig olefination and, finally, a comprehensive trial of acetal deprotection methods for a 1,2 dioxane acetal in the presence of a silyl ether. Chapter 5 summarises the overall findings of this project and outlines possible future avenues for exploration. The full computational data set and experimental procedures, including spectroscopic data, are detailed in Chapter 6.
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    Scalable solid state synthesis of core-chell Pt@Cu2O nanocubes with controlled size and shape
    (University College Cork, 2021-09) Neill, Hazel; Collins, Gillian; Long, Brenda
    This works reports a novel solid state synthesis approach for the formation of shape controlled Pt@Cu2O nanoparticles immobilized onto Cu substrates. High nanoparticle loading was achieved by the use of a self-assembled monolayer consisting of a long chain diamine. The SAM enabled immobilization of citrate stabilized Pt nanoparticles onto the Cu substrate. Annealing under a reducing atmosphere led to the formation of core-shell nanostructures with a cubic morphology. Characterisation showed the nanocubes to consist of a Pt core and crystalline oxide shell. A key question that is addressed in this work was determining the composition of the shell material. A combination of detailed materials characterisation including XPS, XRD and high resolution TEM analysis confirmed the composition to be Cu2O. Preliminary measurements have demonstrated the use of the substrates in glucose sensing applications.
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    Doping of group IV semiconductor nanowires
    (University College Cork, 2020-03) Game, Alexander; Holmes, Justin; Science Foundation Ireland
    As Moore’s Law predicted in the 1960s, advancements in technology have led to an exponential increase in the numbers of transistors required per square inch of integrated circuits, leading to an ever pressing need for smaller transistors. In turn, there is a need for novel transistor architectures and materials, with the conventional Si FETs soon approaching the limits of modern technology. With the need for channel lengths and widths below 7 nm fast approaching, much research has turned to new materials and devices to fulfil these requirements when they are needed. With NWs being prominently used in studies of alternative device architectures, and a resurgence in research of Ge as a semiconductor for FET channels, Ge NWs show great promise as components for novel FET designs. GeSn also shows great potential over Si and Ge due to its direct bandgap allowing for lower energy devices. While most reported syntheses of Ge NWs use gas-based vapour-liquid-solid growths, some research has been reported on solution-based VLS growth of both Ge and Ge Sn NWs, although no literature to date has reported solution-based doping of VLS grown Ge or GeSn NWs. This thesis reports liquid-phase VLS growth and in-situ doping of Ge and GeSn NWs using a variety of dopant precursors. SEM and TEM were used to analyse the morphology of NWs grown. TEM, XRD and Raman Spectroscopy were used to analyse the crystal structures of the wires, including the presence of defects. Raman spectroscopy and EDX analysis were used to determine the atomic composition of the NWs. Electrical testing was also carried out on the NWs. Chapter 1 of this thesis outlines the advantages of the Ge and GeSn NWs over conventional FET materials and architectures, as well as introducing the mechanisms of the growth and doping of semiconductor NWs and summarising the existing literature of doping of NWs, particularly focusing on in situ doping. Chapter 2 outlines the experimental methodology for the synthesis of the Au NPs used for NW synthesis, as well as the syntheses of Ge and GeSn NWs, as well as detailing the equipment and chemicals used. Chapter 3 details how the dopant molecules impact the morphology of the NWs, with decreases in the diameters and lengths of NWs in most samples. The dopants are also shown to decease the NW yield, with most samples yielding cubic crystalline NWs grown in the (111) direction. Dopant precursors are also shown to have prominent effects on the Sn concentration of GeSn NWs, as well as having more pronounced effects on the crystallinity of the NWs. These results are followed by conclusions and an outline of potential future work in this field.
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    Ultrasoft magnetic materials processing and characterisation
    (University College Cork, 2020-08-31) Dixon, Ehren; Rohan, James; Science Foundation Ireland
    The objective of this research was to develop, characterise and test post-processed magnetic materials used for in-package or on-chip devices such as micro-inductors. The electrochemical post-processing has been shown to improve the magnetic properties of the NiFe alloy. The aim of this research was further to test this process on alloys such as CoNiFe as well as integrating these ‘ultrasoft’ magnetic materials into on-chip micro-inductors for device functionality testing. A material with a hysteresis of Hc = <10 A/m is referred to as an “ultrasoft” material. Magnetic devices such as inductors and transformers are essential devices in power supplies. Power supplies have been decreased in size and increased in speed and efficiency over the past few decades with the creation of on-chip power supply circuitries. One key barrier in the miniaturisation of these circuitries in their power storage and transfer devices, inductors, and transformers, which currently occupy ~30% of the circuit’s volume. Decreasing the volume of these devices requires the improvement of their efficiency and functionality, which relates to the magnetic materials used in these devices. Ferrites have been used extensively over the past decades due to their low cost and low loss performance. Unfortunately, ferrite’s low magnetic flux density and resistivity make them less suitable for miniature devices or devices which work at high frequencies. Current alternative high flux materials are limited by high cost or high-power loss and work at very low frequencies. Therefore, there is a need for more efficient magnetic material for improved power supplies. The newly created post-processed magnetic materials and devices were tested for magnetic and electrical properties such as inductance, inductance density, DC resistance, quality factor, and high-frequency response of the devices. They were compared with devices supporting cores made of the as-deposited version of the materials. Oxi-NiFe, the post-processed version of NiFe, saw a noticeable increase in both its electrical and magnetic properties as a material, as well as showing improved properties as a core in the inductor devices, in comparison to NiFe and the NiFe devices. CoNiFe also showed improvement in both electrical and magnetic properties, as well as device improvements when used as a core, in comparison to the standard NiFe. Oxi-CoNiFe saw diminished properties when compared to CoNiFe.
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    The crystal landscape and cocrystallization of primary aromatic sulfonamides
    (University College Cork, 2020-07) Downey, John D.; Lawrence, Simon; Science Foundation Ireland
    This thesis is focused on primary benzenesulfonamides. They have been structurally characterised and analysed for common structural motifs present in the solid state. A systematic investigation of their cocrystallization with a range of neutral, zwitterionic and ionic coformers has been carried, with a strong focus on coformers that have the potential for sulfonamide drug development. Chapter One discusses and illustrates the literature for the solid-state and supramolecular chemistry of benzenesulfonamides; topics covered include non-covalent interactions, synthons, crystal engineering, cocrystallization, eutectic compositions, solvates, biochemistry of sulfa drugs and crystal polymorphism. Chapter Two delves into the crystal landscape of the sulfonamide functional group. In this chapter we critically assess several simple primary aromatic sulfonamides identifying the different motifs present in their crystalline structures. Chapter Three focuses on the design and cocrystallization of sulfonamides with a range of neutral, zwitterion and ionic coformers. Initial screening was complemented by the solid-state characterization of the products obtained. Chapter Four outlines the future work that could be implemented to advance the library of supramolecular synthons for the sulfonamide functional group, in addition to furthering the improvement of sulfonamide drug development whether by using cocrystallization, solvate formation or by eutectic compositions.