From more sustainable isocyanide-based multicomponent reactions to spiro-heterocyclic compound syntheses
- Authors: Salami, Sodeeq Aderotimi
- Date: 2023-10-13
- Subjects: Passerini reaction , Isocyanides , Isothiocyanate , Mechanical chemistry , Organic reaction
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432229 , vital:72853 , DOI 10.21504/10962/432229
- Description: The global pharmaceutical industry has undergone profound transformations in the past two decades in the search for new drugs. For this reason, most pharmaceutical companies made significant investments not only in the development of new drugs but new methodologies. Modern drug development is confronted with the challenge of developing chemical reactions that are highly capable of providing most of the elements of structural complexity and diversity with the fewest possible synthetic steps for the specific target with the most intriguing properties. The discovery of more sustainable, environmentally friendly reactions capable of forming multiple bonds in a single step has been a challenge in organic synthesis over the years. Many organic chemists have recently started focusing on creative ways of reducing environmental pollution. The use of hazardous solvents has been reduced or eliminated in research to limit harm to both people and the environment. The pursuit of this goal has drawn many organic chemists to the study of various sustainable synthetic techniques including catalysis, aqueous organic reactions and mechanochemistry. The scope of this thesis was to apply sustainable techniques to design multicomponent synthetic protocols for the Passerini reaction and further apply these new protocols to construct spiro-heterocyclic compounds, all based on green chemistry principles. There is a need to develop rapid, efficient, and versatile strategies for the synthesis of bioactive molecules via multicomponent reactions. This project tried to avoid some of the pitfalls of traditional approaches, such as toxicity, low yield, long reaction times, harsh conditions, experimental complexity, and limited functionalization scope. This was achieved by focussing on the use of isonitriles and isothiocyanates as key reactive intermediates, and making extensive use of aqueous reaction conditions, mechanochemistry and microwave activation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Authors: Salami, Sodeeq Aderotimi
- Date: 2023-10-13
- Subjects: Passerini reaction , Isocyanides , Isothiocyanate , Mechanical chemistry , Organic reaction
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432229 , vital:72853 , DOI 10.21504/10962/432229
- Description: The global pharmaceutical industry has undergone profound transformations in the past two decades in the search for new drugs. For this reason, most pharmaceutical companies made significant investments not only in the development of new drugs but new methodologies. Modern drug development is confronted with the challenge of developing chemical reactions that are highly capable of providing most of the elements of structural complexity and diversity with the fewest possible synthetic steps for the specific target with the most intriguing properties. The discovery of more sustainable, environmentally friendly reactions capable of forming multiple bonds in a single step has been a challenge in organic synthesis over the years. Many organic chemists have recently started focusing on creative ways of reducing environmental pollution. The use of hazardous solvents has been reduced or eliminated in research to limit harm to both people and the environment. The pursuit of this goal has drawn many organic chemists to the study of various sustainable synthetic techniques including catalysis, aqueous organic reactions and mechanochemistry. The scope of this thesis was to apply sustainable techniques to design multicomponent synthetic protocols for the Passerini reaction and further apply these new protocols to construct spiro-heterocyclic compounds, all based on green chemistry principles. There is a need to develop rapid, efficient, and versatile strategies for the synthesis of bioactive molecules via multicomponent reactions. This project tried to avoid some of the pitfalls of traditional approaches, such as toxicity, low yield, long reaction times, harsh conditions, experimental complexity, and limited functionalization scope. This was achieved by focussing on the use of isonitriles and isothiocyanates as key reactive intermediates, and making extensive use of aqueous reaction conditions, mechanochemistry and microwave activation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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Influence of seasonal dynamics on water quality, microbiome, and plant nutritional markers of an aquaponics system
- Authors: Ibrahim, Labaran
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/455373 , vital:75425
- Description: Restricted access. Expected release date 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
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- Authors: Ibrahim, Labaran
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/455373 , vital:75425
- Description: Restricted access. Expected release date 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
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Synthesis, characterization and host-guest complexes of supramolecular assemblies based on calixarenes and cucurbiturils
- Authors: Baa, Ebenezer
- Date: 2022-10-14
- Subjects: Supramolecular chemistry , Calixarenes , Cucurbiturils , Metal-organic frameworks , Macrocyclic compounds , Drug delivery systems
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365621 , vital:65765 , DOI https://doi.org/10.21504/10962/365621
- Description: The field of supramolecular chemistry has grown large and wide in both deepness of understanding, range of topics covered and scope and applications. Supramolecular self-assemblies are facilitated by a wide range of non-covalent intra and inter molecular interactions that range from hydrogen bonding to π-interaction and van der Waals. Macrocyclic compounds such as cucurbiturils and calixarenes have emerged as important classes of compounds with excellent potential of forming supramolecular assemblies. The porous nature of these compounds enables them to form host-guest supramolecular complexes stabilized by diverse range of non-covalent interactions. Furthermore, these compounds contain donor atoms capable of forming bonds with metal ions to yield metal complexes with interesting porous characteristics that deviate from their traditional hydrophobic cavity. The versatile nature of the resulting pores imply that they can accommodate diverse types of guests. This work explores the synthesis and characterization of a host of calixarenes and cucurbiturils. Self-assembly of these macrocycles with various metal ions results to the formation of porous metal organic framework (MOF) complexes. Four new calixarene typed compounds obtained from aromatic aldehydes and twenty-six cucurbituril metal complexes are reported. These macrocylces and their metal complexes also form supramolecular complexes with DMSO, methanol, isoniazid hydrochloride and ciprofloxacin hydrochlorides through either self-assembly, mechanochemistry and exposure to solvent vapors. The bulk materials have been characterized using nuclear magnetic resonance spectroscopy (NMR), Fourier transformed infrared spectroscopy (FTIR), powder and single crystal diffraction techniques and thermal studies thermogravimetric analysis (TGA) and differential thermal calorimetry (DSC). Data obtained from this study reveals that calixarenes can form supramolecular complexes with a frequently used laboratory solvents with BN22 showing appreciable selectivity for DMSO sorption from a solvent mixture. These compounds also form supramolecular complexes with drug molecules such as isoniazid and ciprofloxacin. Furthermore, the data reveals that choice of synthetic route of supramolecular ensembles dictates if the guest drug molecule will occupy the intrinsic or extrinsic pores of cucurbituril complexes. Biological studies on the obtained complexes reveal that the cucurbituril complexes are non-cytotoxic while the calixarenes show antibacterial activity against Escherichia coli and Staphylococcus aureus. Additionally, the study showed that ciprofloxacin can be successfully released from a calixarene host in a simulated body fluid although the host was also found to cross the dialysis membrane. The results of this study are important in that; - they can be exploited and developed in the selective sorption of certain guests and - that they can be used in the development of drug delivery systems that play a dual role of delivery and therapeutic activity. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Authors: Baa, Ebenezer
- Date: 2022-10-14
- Subjects: Supramolecular chemistry , Calixarenes , Cucurbiturils , Metal-organic frameworks , Macrocyclic compounds , Drug delivery systems
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365621 , vital:65765 , DOI https://doi.org/10.21504/10962/365621
- Description: The field of supramolecular chemistry has grown large and wide in both deepness of understanding, range of topics covered and scope and applications. Supramolecular self-assemblies are facilitated by a wide range of non-covalent intra and inter molecular interactions that range from hydrogen bonding to π-interaction and van der Waals. Macrocyclic compounds such as cucurbiturils and calixarenes have emerged as important classes of compounds with excellent potential of forming supramolecular assemblies. The porous nature of these compounds enables them to form host-guest supramolecular complexes stabilized by diverse range of non-covalent interactions. Furthermore, these compounds contain donor atoms capable of forming bonds with metal ions to yield metal complexes with interesting porous characteristics that deviate from their traditional hydrophobic cavity. The versatile nature of the resulting pores imply that they can accommodate diverse types of guests. This work explores the synthesis and characterization of a host of calixarenes and cucurbiturils. Self-assembly of these macrocycles with various metal ions results to the formation of porous metal organic framework (MOF) complexes. Four new calixarene typed compounds obtained from aromatic aldehydes and twenty-six cucurbituril metal complexes are reported. These macrocylces and their metal complexes also form supramolecular complexes with DMSO, methanol, isoniazid hydrochloride and ciprofloxacin hydrochlorides through either self-assembly, mechanochemistry and exposure to solvent vapors. The bulk materials have been characterized using nuclear magnetic resonance spectroscopy (NMR), Fourier transformed infrared spectroscopy (FTIR), powder and single crystal diffraction techniques and thermal studies thermogravimetric analysis (TGA) and differential thermal calorimetry (DSC). Data obtained from this study reveals that calixarenes can form supramolecular complexes with a frequently used laboratory solvents with BN22 showing appreciable selectivity for DMSO sorption from a solvent mixture. These compounds also form supramolecular complexes with drug molecules such as isoniazid and ciprofloxacin. Furthermore, the data reveals that choice of synthetic route of supramolecular ensembles dictates if the guest drug molecule will occupy the intrinsic or extrinsic pores of cucurbituril complexes. Biological studies on the obtained complexes reveal that the cucurbituril complexes are non-cytotoxic while the calixarenes show antibacterial activity against Escherichia coli and Staphylococcus aureus. Additionally, the study showed that ciprofloxacin can be successfully released from a calixarene host in a simulated body fluid although the host was also found to cross the dialysis membrane. The results of this study are important in that; - they can be exploited and developed in the selective sorption of certain guests and - that they can be used in the development of drug delivery systems that play a dual role of delivery and therapeutic activity. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
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The fiction of scarcity: conceptualising scarcity in terms of global justice
- Authors: Brotherton, Michelle
- Date: 2022-04-07
- Subjects: Scarcity Philosophy , Distributive justice , Political science Philosophy , Philosophy , Justification (Ethics) , Fallacies (Logic)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294526 , vital:57229 , DOI https://dx.doi.org/10.21504/10962/294526
- Description: This thesis intends to contribute to the discourse on global justice as it pertains to resources, the distribution of resources, and the allocation of resources. The focus is on the concept of scarcity. I examine scarcity for how it is understood, interpreted, and applied in the literature on global justice. This thesis argues that scarcity lacks conceptual clarity in the discourse on global justice and argues that if scarcity is misconstrued, the consequences can be severe. Conceptual clarity is thus necessary to ensure that scarcity is properly referred to in the discourse on global justice so that scarcity is not erroneously used when justifications are sought for material deprivation and consequent human suffering. In the process, I will also examine how scarcity is used as a justification in instances of material deprivation and why this is problematic. Given the lack of conceptual clarity regarding scarcity, I argue that reliance on scarcity as justification may be erroneous. The conflation of absolute scarcity and relative scarcity may amount to a category mistake. This thesis purports to clarify scarcity conceptually in the context of global justice. In doing so, I recommend that a resource-centric approach to resource scarcity is adopted to accurately account for the scarcity status of resources. A resource-centric approach to resource scarcity based on a more nuanced understanding of scarcity avoids the potential category mistake. Such an approach ensures that material deprivation and consequent human suffering are not wrongfully attributed to scarcity. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2022
- Full Text:
- Authors: Brotherton, Michelle
- Date: 2022-04-07
- Subjects: Scarcity Philosophy , Distributive justice , Political science Philosophy , Philosophy , Justification (Ethics) , Fallacies (Logic)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294526 , vital:57229 , DOI https://dx.doi.org/10.21504/10962/294526
- Description: This thesis intends to contribute to the discourse on global justice as it pertains to resources, the distribution of resources, and the allocation of resources. The focus is on the concept of scarcity. I examine scarcity for how it is understood, interpreted, and applied in the literature on global justice. This thesis argues that scarcity lacks conceptual clarity in the discourse on global justice and argues that if scarcity is misconstrued, the consequences can be severe. Conceptual clarity is thus necessary to ensure that scarcity is properly referred to in the discourse on global justice so that scarcity is not erroneously used when justifications are sought for material deprivation and consequent human suffering. In the process, I will also examine how scarcity is used as a justification in instances of material deprivation and why this is problematic. Given the lack of conceptual clarity regarding scarcity, I argue that reliance on scarcity as justification may be erroneous. The conflation of absolute scarcity and relative scarcity may amount to a category mistake. This thesis purports to clarify scarcity conceptually in the context of global justice. In doing so, I recommend that a resource-centric approach to resource scarcity is adopted to accurately account for the scarcity status of resources. A resource-centric approach to resource scarcity based on a more nuanced understanding of scarcity avoids the potential category mistake. Such an approach ensures that material deprivation and consequent human suffering are not wrongfully attributed to scarcity. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2022
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