The Optimization of Halogen-Bonding Aryl-Ethynyl Receptors
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Date
2022-10-26
Authors
de Faria, Thaís
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Publisher
University of Oregon
Abstract
Supramolecular chemistry is an ever-growing area in science that studies noncovalent interactions between small molecules and/or ionic species through molecular recognition or self-assembly. Host-guest chemistry is a branch of this field that pulls a lot of inspiration from nature in hopes to harness synthetic control for a broad range of applications, including encapsulation for pollution remediation, cellular ion transport channels in therapeutics, and anion sensing for in vivo cell imaging. Hydrogen bonds are the most popularly studied noncovalent interaction because of their rich presence in naturally occurring processes, their strength, and directionality. In the past 20 years, halogen bonds have emerged as another prominent form of intermolecular interaction that have similar directionality as hydrogen bonds but have shown to bind guests more competitively in water¬–a medium that makes up most of the applications of these systems.
In this dissertation, we aim to modify mono- and bi-dentate arylethynyl halogen bond (XB) scaffolds with the purpose of optimizing their selectivity of binding target analytes in polar solvents. In Chapter II, we attempt to synthesize a zwitterionic bi-dentate XB host receptor that features propyl sulfonate, a water-solubilizing functional group, in hopes to measure its binding affinity with phosphate in aqueous media.
In Chapter III, we assess the influence of substituent effects, by modifying tunable groups with various EWGs and EDGs, in neutral versus charged receptors in a family of novel meta “one-armed” receptors. In Chapter IV, we continue the investigation of mono-dentate arylethynyl receptors by studying the binding geometry of the ortho isomer. Through the comparison of the two isomers (ortho and meta), we can elucidate chloride’s affinity to each binding pocket size. In Chapter IV, we also serendipitously discover a novel vinylic XB donor that is shown to participate in halogen bonding with chloride in a crystal structure. The following results of the binding geometries, experimental binding trends, and theoretical calculations can heavily influence future designs of small-molecule, halogen bonding receptors from this scaffold family to bind to smaller anions more successfully.
This dissertation contains previously published, soon to be published, and unpublished co-authored materials.
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Keywords
Anion Binding, Physical Organic Chemistry, Supramolecular Chemistry