Doctor of Philosophy (PhD)
The design of synthetic receptors for the recognition and sensing of saccharides and amino acids is currently a major challenge. This is due to inherent structural similarity and a lack of chromophoric or fluorophoric properties of these compounds. The synthesis and study of novel detection agents for bioactive molecules as well as mechanistic studies are presented herein. The elucidation of the mechanism by which tetraarylboronic acid resorcinarene interact with sugar molecules and promote a solution color change is explored. This vast collaborative study, reveals that DMSO solutions of boronic acid functionalized resorcinarene macrocycles afford visual color changes upon heating or standing and in the presence of saccharides. We found that the solution color is due to macrocycle ring opening and oxidation. Condensation reactions catalyzed by acid formed in situ from DMSO are responsible for xanthene dye formation. As a result of our mechanistic knowledge we were able to design and synthesize a variety of novel receptors. To date two selective receptors for the purpose of saccharide sensing have been synthesized. The first is a rhodamine-derived boronic acid receptor, for use in a novel post-column chromatographic procedure for the detection of saccharides. The second involves the designed and synthesis of a fluorescein-derived phosphonic acid receptor, which interacts with saccharides amino acids and anions via metal complexation. As an extension of our work with saccharides we are exploring the detection of amino acids. We have discovered a highly selective new method for the facile determination of cysteine and homocysteine via a fluorescein dialdehyde derivative. In addition, we have made progress towards the selective, direct colorimetric and fluorometric differentiation between cysteine and homocysteine in the presence of each other despite their great similarity in structure.
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St. Luce, Nadia Nadette, "Synthesis, characterization and study of novel reagents for the detection of saccharides and amino acids" (2004). LSU Doctoral Dissertations. 2445.
Robert M. Strongin