Synthesis and applications of novel fluorescent and colorimetric coumarin-based sensors towards analyte sensing in aqueous systems
- Authors: Battison, Aidan Leigh
- Date: 2022-04
- Subjects: Water-supply engineering--Technological innovations , Polymers--Optical properties , Fluorescent polymers
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55954 , vital:54558
- Description: The continuous growth of mankind has not been considerate to the environment. The release of millions of tonnes of toxic heavy metal cations and anionic species through industrial, mining, agricultural, and electronic dumping has led to disease and, in many instances, death. This is usually suffered by low-income informal populations residing in third world countries. Moreover, many unnecessary deaths of children are becoming more prevalent because of consumption and contact with contaminated water, agricultural, and animal sources. Bioaccumulation of these toxic species in fish, plants, and animals, inevitably make their way back to the unaware general population. As growth by mining, agriculture, and electronics are indeed vital aspects of human development, the negative side effects of these activities usually continue unregulated. Therefore, as these processes are set to continue until more stringent regulatory processes are put into legislature; low-cost, sensitive, selective organic based sensors are a step in the right direction towards highlighting the need for environmental restoration and remediation; whilst also aiming to preventing unnecessary disease and death in the process. Herein, coumarin derived small-molecule fluorescent and colorimetric sensors for the quantitative and qualitative assessment of cationic and anionic species in aqueous and organic media are described. Ten fluorescent sensors supporting 1,4-disubstituted triazolyl moieties were synthesized according to Cu(I)-catalyzed azide-alkyne cycloaddition “click” reactions. These sensors were screened for their cationic and anionic affinities in a variety of solvent systems. Majority of the sensors responded well towards Fe3+, characterized by a strong fluorescent quenching response with a good degree of sensitivity and selectivity. Selected sensors were further investigated for their affinities towards anionic species; however, they did not display the same degree of selectivity or sensitivity towards these chosen anions. Titration studies of selected sensors with Fe3+ were able to be used towards determining the modes of fluorescent quenching; the photophysical mechanisms by which quenching occurs; stoichiometric binding ratios, association constants, and the number of coordination sites present between the sensors and Fe3+. Reversibility studies of the sensor-metal complex was investigated with EDTA. Partial reversibility was achieved for the chosen sensors with Fe3+. Hydrogen potential studies further described the application of these sensors over a good pH range. The binding site between the sensors and Fe3+ was investigated by NMR studies. , Thesis (PhD) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Battison, Aidan Leigh
- Date: 2022-04
- Subjects: Water-supply engineering--Technological innovations , Polymers--Optical properties , Fluorescent polymers
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55954 , vital:54558
- Description: The continuous growth of mankind has not been considerate to the environment. The release of millions of tonnes of toxic heavy metal cations and anionic species through industrial, mining, agricultural, and electronic dumping has led to disease and, in many instances, death. This is usually suffered by low-income informal populations residing in third world countries. Moreover, many unnecessary deaths of children are becoming more prevalent because of consumption and contact with contaminated water, agricultural, and animal sources. Bioaccumulation of these toxic species in fish, plants, and animals, inevitably make their way back to the unaware general population. As growth by mining, agriculture, and electronics are indeed vital aspects of human development, the negative side effects of these activities usually continue unregulated. Therefore, as these processes are set to continue until more stringent regulatory processes are put into legislature; low-cost, sensitive, selective organic based sensors are a step in the right direction towards highlighting the need for environmental restoration and remediation; whilst also aiming to preventing unnecessary disease and death in the process. Herein, coumarin derived small-molecule fluorescent and colorimetric sensors for the quantitative and qualitative assessment of cationic and anionic species in aqueous and organic media are described. Ten fluorescent sensors supporting 1,4-disubstituted triazolyl moieties were synthesized according to Cu(I)-catalyzed azide-alkyne cycloaddition “click” reactions. These sensors were screened for their cationic and anionic affinities in a variety of solvent systems. Majority of the sensors responded well towards Fe3+, characterized by a strong fluorescent quenching response with a good degree of sensitivity and selectivity. Selected sensors were further investigated for their affinities towards anionic species; however, they did not display the same degree of selectivity or sensitivity towards these chosen anions. Titration studies of selected sensors with Fe3+ were able to be used towards determining the modes of fluorescent quenching; the photophysical mechanisms by which quenching occurs; stoichiometric binding ratios, association constants, and the number of coordination sites present between the sensors and Fe3+. Reversibility studies of the sensor-metal complex was investigated with EDTA. Partial reversibility was achieved for the chosen sensors with Fe3+. Hydrogen potential studies further described the application of these sensors over a good pH range. The binding site between the sensors and Fe3+ was investigated by NMR studies. , Thesis (PhD) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Synthesis and application of novel coumarin-triazole-based polymeric sensors towards metal ion sensing
- Authors: Battison, Aidan Leigh
- Date: 2018
- Subjects: Polymers -- Optical properties , Polymers -- Electric properties Biosensors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23636 , vital:30591
- Description: One of the greatest challenges in the South African society is the pollutants which we are exposed to within our environment. The mismanagement and release of toxic analytes via different chemical, agricultural and industrial processes has led to a critical need for advanced monitoring systems for environmental protection, remediation and restoration. Industrial processes release a plethora of different pollutants into the earth, atmosphere, and aquatic ecosystems. Most pollutant causing activities are due to mining, agriculture, industry and chemical storage. Most contaminants released by these processes are not biodegradable and may be able to exude into water systems where they present an immense threat to environmental and human health. The number of different analytes released into the environment is greater than the number of sensors able to detect these species. Clearly, there is a need for a rapid and low-cost means of detection, recognition, and monitoring of these analytes. Fluorescent coumarin-triazole-based polymeric materials were designed and investigated as potential sensors for these metal ionic species. The Cu(I)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes was the focus method of polymerization to form the fluorescence enhancing triazole moiety. The coumarin-triazole units formed the backbone of these polymeric material. The photophysical properties of the starting monomers and polymers were investigated in THF solvent. The polymers showed to have higher absorption and emission intensities than their respective starting monomers. The chemosensing capabilities of the polymers for metal ions were investigated through their emission properties. The polymers showed to have the greatest response towards Hg2+ and Ag+. Furthermore, the polymers displayed a reversible response towards Hg2+ in the presence of EDTA. The most responsive and reversible polymer system was applied for metal sensing capabilities towards Hg2+ from a known water source. This polymer proved to be a sensitive and reversible chemosensor for Hg2+ ions. The site of metal complexation on the polymer systems was verified by 1H NMR and FT-IR spectroscopy and was found to be mainly the triazole moieties from the polymer backbone. Finally, the possible mechanism for the fluorescent response of Hg2+ and Ag+ was also investigated.
- Full Text:
- Date Issued: 2018
- Authors: Battison, Aidan Leigh
- Date: 2018
- Subjects: Polymers -- Optical properties , Polymers -- Electric properties Biosensors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23636 , vital:30591
- Description: One of the greatest challenges in the South African society is the pollutants which we are exposed to within our environment. The mismanagement and release of toxic analytes via different chemical, agricultural and industrial processes has led to a critical need for advanced monitoring systems for environmental protection, remediation and restoration. Industrial processes release a plethora of different pollutants into the earth, atmosphere, and aquatic ecosystems. Most pollutant causing activities are due to mining, agriculture, industry and chemical storage. Most contaminants released by these processes are not biodegradable and may be able to exude into water systems where they present an immense threat to environmental and human health. The number of different analytes released into the environment is greater than the number of sensors able to detect these species. Clearly, there is a need for a rapid and low-cost means of detection, recognition, and monitoring of these analytes. Fluorescent coumarin-triazole-based polymeric materials were designed and investigated as potential sensors for these metal ionic species. The Cu(I)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes was the focus method of polymerization to form the fluorescence enhancing triazole moiety. The coumarin-triazole units formed the backbone of these polymeric material. The photophysical properties of the starting monomers and polymers were investigated in THF solvent. The polymers showed to have higher absorption and emission intensities than their respective starting monomers. The chemosensing capabilities of the polymers for metal ions were investigated through their emission properties. The polymers showed to have the greatest response towards Hg2+ and Ag+. Furthermore, the polymers displayed a reversible response towards Hg2+ in the presence of EDTA. The most responsive and reversible polymer system was applied for metal sensing capabilities towards Hg2+ from a known water source. This polymer proved to be a sensitive and reversible chemosensor for Hg2+ ions. The site of metal complexation on the polymer systems was verified by 1H NMR and FT-IR spectroscopy and was found to be mainly the triazole moieties from the polymer backbone. Finally, the possible mechanism for the fluorescent response of Hg2+ and Ag+ was also investigated.
- Full Text:
- Date Issued: 2018
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