Sewanee Senior Theses 2024

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    Synthesis, characterization, and transfer hydrogenation catalysis of mid-row transition metals and the investigations of regulatory mechanisms of the OAS-RNase Land PKR pathways for RNA sensing
    (University of the South, 2024-05) Keuk, Channita
    A. The synthesis of a series of chlorine-substituted acetylacetonate cobalt(III) complexes was attempted by varying the stoichiometric ratios of the starting materials in solution. Following the synthesis, the complexes were purified using column chromatography and subsequently characterized using ultraviolet-visible, infrared, and nuclear magnetic spectroscopy and x-ray crystallography to analyze the effects of these chlorine substitutions on the Co(III) metal center. Based on the spectroscopic analysis of the complexes, these substitutions yielded discernible differences in the electronic properties of the Co(III) center. Characterization of these complexes can lead to its potential applications in catalysis and photochemical studies. B. Alcohols play an extremely important role in the synthesis of larger organic compounds such as perfumes, sweeteners, and pharmaceuticals. The reduction of ketones to alcohols via traditional metal-catalyzed hydrogenation has multiple drawbacks such as the use of pressurized hydrogen gas and requiring high temperatures. Organometallic catalysts can eliminate some of these by utilizing alternative reaction conditions that are more environmentally friendly and can occur at much lower temperatures. Ruthenium(II) metal complexes with 4-aminopyridine (ampy) and diphenylphosphinobutane (dppb) were synthesized with the replacement of the para-hydrogen on the pyridine ring with a chlorine (Cl) group and a methoxy (OMe) group to study the effects of electron withdrawing groups (EWG) and electron donating groups (EDG) on the electronic profiles of the ruthenium center. NMR spectroscopy, UV-Vis spectroscopy, cyclic voltammetry, and X-ray crystallography were used to characterize each compound. Studies have shown that the ampy based ruthenium(II) metal complexes are capable of isomerization; thus, the rates of trans-to-cis isomerization were. The transfer hydrogenation catalysis data shows that these ampy-ruthenium(II) systems are highly capable of transfer hydrogenation, with selectivity for ketone functional groups. C. N-Heterocyclic carbenes (NHC) are excellent ligands for the coordination and reactivity of cobalt complexes in the transfer hydrogenation catalysis of ketone substrates. The traditional synthesis of such ligands is a time-consuming process that hinders efficient synthesis of metal complexes. Thus, an alternative synthetic method via a microwave reactor for several N-substituted imidazole-based NHC pincer ligands was developed to reduce reaction time from three days to under two hours. Seven different compounds were synthesized and characterized using 1H and 13C nuclear magnetic resonance spectroscopy. Several compounds resulted in mixtures of unreacted starting material and the desired products, which were then cleanly isolated using column chromatography purification. D. Transfer hydrogenation offers an alternative to selectively target specific functional groups on a molecule while keeping the others intact. An abundance of previously published research focuses on expensive transition metal catalysts of ruthenium, platinum, and more. Given the reactivity of ruthenium(II) systems in transfer hydrogenation, the shift to utilizing cobalt(II)-based catalysts systems allows for a more cost-efficient method due to the natural abundance of these first-row transition metals. The synthesis of a series of imidazole-based N-heterocyclic carbene (NHC) cobalt(II) complexes are being explored in order to generate a diverse range of metal complexes with varying electron-donating and withdrawing substitutions, as well as sterically bulky R-groups, on the imidazole ligand. Catalytic studies are also being done to determine if these changes in electron density around the metal center can have an effect on the rates of catalysis. E. In the field of transition metal catalysis, specific analytical techniques must be employed in order to quantitatively assess the rates and percent yield of catalytic conversion of the substrates. For studies involving paramagnetic metal complex species, the common method of NMR spectroscopy proves to be challenging as it requires various additional steps for sample preparation. Thus, an alternatively strategy using the gas chromatography mass spectrometer (GC-MS) allows for quantitative assessment of the amount of product converted by the catalyst through the use of a calibration curve. A series of calibration curves using benzophenone and benzhydrol were generated in an attempt to accurately assess the percent yields of the products in Co(II) imidazole-NHC catalyzed transfer hydrogenation. Studies are currently still ongoing to find the optimal sample preparation techniques to generate an accurate calibration curve. F. The vaccinia virus (VACV) utilizes the hypophosphorylation of serine/arginine-rich (SR) proteins, which are essential to the host alternative RNA splicing machinery, to induce host shut-off. In response to viral infections, the Protein Kinase R (PKR) pathway is activated in order to prevent viral RNA translation. To explore whether defects in RNA splicing generates ligands for PKR activation, western blots were used to probe for PKR activation in A549 cells during SR inhibition. Upon treatment with SR inhibitors and infection with the vaccinia virus for 24 hours, A549 cells were collected and probed for PKR activity via western blot. Contrary to published literature, it was found that VACV infection did not suppress SR phosphorylation based on the western blot analysis, and chemical inhibition of SR proteins do not induce PKR activation. G. As dsRNAs are the hallmark of viral infections, RNA sensing becomes an important component of host innate immunity. The oligoadenylate synthetase (OAS)-RNase L system, a dsRNA-sensing pathway of interest, provides a mechanism of action against dsRNAs within the body. Given the potency of its activation, this pathway is not only highly regulated through cellular mechanisms but also heavily antagonized by viruses. To test whether regulation of the OAS/RNase L pathway occurs at the post translational level, RNase L wildtype and K684R mutant plasmids were generated to test the effect of acetylation of the enzyme and its overexpression on its activation using bioanalyzer assays. Based on the assays conducted, there appears to be no activation of RNase L due to overexpression of the mutant plasmids. However, due to experimental errors, the assays comparing the transfection of PCDEF3 empty vector, wildtype RNase L, and RNase L K684R mutant followed by polyIC and 2-5A treatments failed to show any discernable differences in RNA degradation. Further studies are needed in order to accurately assess the RNA integrity in the bioanalyzer assays studying the effects of hyperacetylation of RNase L on its activation.
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    Synthesis and Characterization of Potential Anti-Cancer Platinum Complexes with Indazole and its Derivative
    (University of the South, 2024-05) Humeniuk, Yullia
    In 1978, the FDA marked a milestone with the clinical approval of Cisplatin, the pioneering metal-based anticancer chemotherapeutic. Its effectiveness sparked great interest in understanding its behavior and developing new platinum pharmaceuticals. Platinum(II) complexes dominate a majority of drug discovery research to date; however, platinum(IV) complexes have also begun to be explored in the belief that they will allow new therapy avenues with fewer side effects, acting as potential prodrugs. This exploration extends beyond platinum, delving into various metal systems, such as ruthenium. Inspired by the ruthenium anticancer complex (KP1019) and the scarcity of metal complexes featuring indazole, we explore the chemistry of platinum-indazole complexes. In recent years, our group yielded a library of new bisindazole Pt(IV) and Pt(II) complexes, enriching the landscape of potential anti-cancer agents. These complexes have been characterized via spectroscopy and crystallography, and the initial experiments suggest at least one new compound interacts with a DNA model.
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    "Sybaritic Privacy" Or, How Mr. Compson Lost His Body in Absalom, Absalom!
    (University of the South, 2024-05) Frazee, Meridith
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    'The Best Days Are the First To Flee': Willa Cather, Marilynne Robinson, and the Pastoral Ideal of America's Midwest
    (University of the South, 2024-05) Schupack, Carrie
    The pastoral as a literary subgenre offers unique insight into the subjects it depicts. While characterized by their focus on the rhythms of rural life and agrarianism, pastoral works are most frequently written by those who have limited experience with actual forms of agrarian labor. The pastoral as it has been presented in American literature has a rich lineage, with writers like Thomas Jefferson, Henry David Thoreau, and Robert Frost typifying the literary ideal of nature, landscape, and all that those things entail. In this essay, I will examine how two works of modern American literature, My Antonia, published in 1918 by Willa Cather, and Gilead, published in 2004 by Marilynne Robinson, expand on the tradition of the pastoral and make it relevant to a modern audience. My Antonia, which takes on themes such as the consequences of gendered labor and the rise of industrialization in the rural Midwest, paves the way for Gilead, written nearly a hundred years later. Gilead also dwells on a rapidly changing rural America, although its focus is less overtly agricultural. Both novels explore what it means to live in America's heartland, and what the moral implications of globalization and mechanization are. Gilead especially examines the influences and consequences of Christianity on rural America, while My Antonia takes into account the immigrant perspective, and what that discloses about society at the end of the nineteenth century.
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    From Paternalism to Paternity: The Modern Southern Gentleman in the American South
    (University of the South, 2024-05) Richard Alan Waters Il
    As William Faulkner often does, his bildungsroman, The Unvanquished, spotlights a dilemma in the old social hierarchy of the American South. The Southern Gentleman, an aristocratic figure whose principal role was to prevent chaos from engulfing his community, finds himself in a present that rejects him. However, Faulkner, through his main character, Bayard Sartoris, introduces the potential for a revised version of the Southern Gentleman who can exist in the contemporary world. Found in a place where he no longer belongs, the Southern Gentleman, a man who mirrors the qualities of the Chivalric tradition who historically was considered the patriarchal figure of his community, transforms into a man with modified masculinity, prompting him to become a paragon of fatherhood. This project investigates the Southern Gentleman's shift from paternalism to paternity by analyzing Harriett Beecher Stowe's Uncle Tom 's Cabin, Harper Lee's To Kill A Mockingbird, Walker Percy's The Last Gentleman, and Will Alexander Percy's autobiography Lanterns on the Levee as means to begin uncovering the complicated nature of gender and its strange relationship with authority in the American South.