Degree
Doctor of Philosophy (PhD)
Department
Chemistry
Document Type
Dissertation
Abstract
The dissertation is about the design, synthesis, and characterization of synthetic receptors for anion binding or metal-ion binding. Chapters 1 and 3 introduce anion supramolecular chemistry and the development of lithium-ion receptors. Chapters 2, 4, and 5 are focused on the projects for my Ph.D. studies.
In Chapter 2, we recognized that nitrone CH groups are polarized due to the positive formal charge of the adjacent nitrogen atom. Therefore, we hypothesized that the electropositive CH proton would be suitable for binding anions. As a proof-of-concept study, we synthesized acyclic anion receptors with two nitrone moieties using condensation reactions between aryl-aldehydes and m-phenylenedihydroxylamines. The solid-state structure of dinitrones revealed CH•••O hydrogen bonds. Anion-binding properties were investigated using 1H NMR titration.
In Chapter 4, we designed a bis-diimide-based scaffold to investigate the optimal geometries for binding Li+ in acyclic systems. Specifically, the bis-diimide with a thiazole central core exhibited moderate binding affinity for Li+, while the one with a pyridine central core did not bind Li+. The single crystal structures of bis-diimides with pyridine or thiazole as central cores explained the observed differences in binding affinity, which we attribute to variations in the distance between two carbonyl groups and dihedral angles between the bis-diimide groups and the central cores. The binding property of thiazole-bis-diimide was investigated using 1H NMR titration with Na+ and Li+. The solid-state structure showed a 2:2 complex with LiClO4 in the solid state.
In Chapter 5, we designed preorganized lithium-ion receptors based on dinaphthofuran. Dinaphthofuran was first synthesized in a single-step oxidative coupling reaction with a major focus on natural product synthesis. We were able to obtain its solid-state structure and recognized that the three oxygen groups were locked close in proximity. Our preliminary calculations showed that converting two methoxy groups into furans would provide a preorganized binding pocket for Li+. Our first target receptor is a helical receptor with five oxygen atoms for metal binding. We envision that this compound could bind Li+ with high binding affinity and selectivity.
Date
11-11-2023
Recommended Citation
He, Xuxian, "Synthetic Receptors for Anion Binding or Metal-Ion Binding" (2023). LSU Doctoral Dissertations. 6298.
https://repository.lsu.edu/gradschool_dissertations/6298
Committee Chair
Lee, Semin