Degree
Bachelor of Science (B.S.)
Major(s)
Chemistry
Document Type
Immediate Campus-Only Restricted Access
Abstract
Metalloenzymes have garnered significant interest in bioinorganic research due to their ability to use earth-abundant metals (i.e., iron, copper, manganese) to conduct reactions in an environmentally friendly manner. Manganese-catalyzed reactions have been extensively studied for O2 activations, superoxide disproportionation, and water oxidation. Additionally, manganese catalysts have been investigated in alkene oxidative cleavage, an essential process in the pharmaceutical and synthetic industries. The primary industrial method employed for this reaction is ozonolysis, a stoichiometric approach that utilizes harsh and toxic conditions. For example, (+)-artemisinin and 24(S)-hydroxyvitamin D2 are two pharmaceutical drugs that utilize ozonolysis in the synthetic procedure to cleave the alkene to the final product or to produce the intermediate for the final product. In addition to ozonolysis, KMnO4, photocatalysis, and several stoichiometric or catalytic methods have also been developed to circumvent the high waste of ozonolysis. While these methods are effective, some still depend on harsh and toxic conditions. In addition, there is a lack of selectivity between the thermodynamically favored cleaved product and the kinetically favored product, epoxide. The biological system TM1459 is a metalloprotein that has been shown to oxidatively catalyze alkenes in vitro in the presence of manganese, utilizing a four-histidine metal binding site. Previously, our group developed a tetradentate ligand to model this enzyme with two pendant imidazoles. However, when applied to water oxidation catalysis, the complex proved unstable under catalytic conditions, and the ligand was weakly bound to manganese. Subsequently, we aim to incorporate pyridinol donors into the ligand to enhance stability under catalytic conditions, as they can deprotonate to the pyridonate, thus making the ligand a more substantial donor.
This thesis details the synthetic efforts to produce this ligand. The first step involves a lithium halogen exchange with 6-bromo-2,2-bipyridine to facilitate a nucleophilic attack on the ketone. This step is analyzed under various temperatures, metal-halogen exchange sources, and reaction time conditions. 1H NMR and gas chromatography-mass spectroscopy (GC-MS) were utilized to analyze each attempt to determine whether the product was formed and identify any side products generated during the reaction.
DOI
https://doi.org/10.54718/HFJU2567
Date Defended
4-25-2025
Funding Source
NIH R15
Thesis Director
Sid E. Creutz
Second Committee Member
Joseph P. Emerson
Third Committee Member
Holli H. Seitz
Recommended Citation
Greer, Jennifer R., "Bipyridine-containing, bio-inspired ligand to support manganese for oxidative catalysis" (2025). Honors Theses. 152.
https://scholarsjunction.msstate.edu/honorstheses/152
