Investigation of the synthesis and characterisation of spiro orthocarbonates and heterocyclic orthocarbonates
- Authors: Cuthbertson, Jarryd Pierre
- Date: 2024-04
- Subjects: Chemistry, Analytic , Analytical chemistry , Chemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63678 , vital:73578
- Description: A series of mostly asymmetrical spiro orthocarbonates and heterospirocyclic derivatives of orthocarbonic acid was synthesized from 2,2-dichlorobenzodioxole and a number of difunctional reagents. A systematic study of the size of the chelate rings formed around the spirocentric carbon atom was conducted by selecting representative samples of aliphatic and aromatic diols. The feasibility and scope of potential starting materials used was expanded by reacting DCBD successfully with thiols. Molecular structures of these compounds were confirmed using diffraction studies on single crystals. All compounds were analyzed using multinuclear NMR. DFT calculations performed on the compounds allowed for the development of equations that can accurately predict 13C chemical shifts of SOCs. Furthermore, the experimental NMR spectroscopy gave rise to an increment shift system for the 13C NMR shifts allowing for further assignment of carbon atom positions in compounds with multiple possible bonding patterns. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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- Date Issued: 2024-04
Preparation and Investigation of coumarin-based chemosensors towards sensing of ions using UV studies in aqueous systems
- Authors: Kotze, Tyla
- Date: 2024-04
- Subjects: Chemistry, Analytic , Water chemistry , Ionic solutions , Aquatic ecology , Geochemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64116 , vital:73654
- Description: Humanity's unrelenting expansion has shown little regard for the environment, and this has resulted in tons of toxic heavy metal cations and anions being released into the environment through industrial, agricultural, electronic, and mining dumping. The release of these toxic heavy metals can cause diseases and sometimes lead to death, especially in third-world countries with low-income that reside in informal settlements, who suffer the most. Furthermore, the release of these toxins eventually finds their way back into the environment through bioaccumulation in fish, plants and animals. Although there is an ever need for the growth of these industries; low-cost, sensitive, selective, and organic-based sensors is a positive step forward in highlighting the need for environmental restoration and remediation, whilst striving to avoid unnecessary disease and death through this development. In this project, coumarin-based chemosensors for the detection of cationic and anionic species in aqueous and organic media are described. This project involves the synthesis of six different coumarin-based ether derivatives (E2-E5) and coumarin-based ester derivatives (H1-H2). FT-IR, 1H NMR and 13C NMR were used to confirm the structures of all sensors. The abilities of these novel compounds as chemosensors for detection of cations and anions were investigated using UV-vis analysis. These compounds displayed a favourable interaction with Fe2+ and Fe3+ ions with an increase in absorbance. Ether derivatives E2-E5 did not display any degree of selectivity or sensitivity towards the chosen anions. It was found that in the presence of FeCl2, sensors H1 and H2 displayed a degree of selectivities and further investigations were therefore carried out. From the titration experiments, the limit of detection, limit of quantification and association constants were determined. Job’s plot analyses were performed to determine the binding ratios, which was supported by Benesi-Hildebrand studies. The binding ratio between the sensors and metal cations during complexation was found to be 1:1. Reversibility studies were carried out using EDTA to determine whether the sensors could be reused. Molecular Modelling studies were used to determine the most preferred binding sites. Lastly, real-life application screenings were also run to determine if the sensors will be able to be used in real-life scenarios. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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- Date Issued: 2024-04