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Chaudhry, Mohammad Talha

University of British Columbia

Supramolecular chemistry is a vast field covering aspects of organic, inorganic, analytical, and physical chemistry. This thesis presents several projects based on Schiff base macrocycles that show the diversity of functionality obtained using such a simple building block. This thesis has two main themes: the study of metal-free macrocycles and the self-assembly of metallomacrocycles. Diamines and dialdehydes were used in the first set of projects to construct either [2+2] or [3+3] Schiff base macrocycles through a one-pot self-assembly method. These compounds were investigated for their ability to bind to small cationic guests. Specifically, a [3+3] macrocycle was used to show the binding of C2v-symmetric ammonium guests and study the equilibria between internal and external host-guest complexes (Chapter 3). Also, partial tautomerization of the molecular host occurred following guest binding. A [2+2] macrocycle with a crown-ether-like cavity was investigated for binding of simple spherical guests (Chapter 5). Detailed spectroscopic studies showed that this class of [2+2] macrocycles showed a strong preference for 2:1 binding stoichiometry. Lastly, the complex energy landscape and multiple conformational equilibria that arise from using sterically congested aldehydes to construct [3+3] macrocycles were explored (Chapter 4). Two macrocycle conformers were obtained that had a substantial energy barrier for rotation. In addition, mild oxidation of the macrocycle using singlet oxygen was shown to facilitate free rotation in the system, yielding a single endoperoxide macrocycle. The second theme involves using hemi-salphen ligands with vacant binding sites to prepare metallomacrocycles through a one-pot self-assembly approach (Chapter 2). Attempts to prepare a C₅ symmetric imine macrocycle proved unsuccessful. However, two new multimetallic complexes were obtained using an unconventional uranyl(VI) template. As a result, a tetranuclear cluster housed within an octameric macrocycle and a dimetallic cluster within a cyclic hexamer macrocycle were obtained.

Text

2025-04-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/81131

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/