Date of Award
Chemistry and Biochemistry
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This thesis presents the design, synthesis and characterization of rotaxane, pseudorotaxane and rotaxane ligands and their resulting coordination to metal centers. Chapter 1 introduces the concepts of interpenetrated and interlocked molecules, molecular motion, metal-ligand interactions and metal organic rotaxane frameworks (MORFs). Chapter 2 explores the preliminary studies of the coordination ability of a model compound containing a xylene backbone with two sulphur donor atoms to a range of metal ions with various geometries. This was followed by the synthesis of a new thioether crown ether ligand and the resulting coordination of this ligand with the same metal centers studied with the model ligand. Where possible, the single crystal X-ray data for these coordination complexes was collected and has been presented. In chapter 3, this new thioether crown ether was used in the formation of rotaxane ligands. Upon the addition of silver(I), the sulphur atoms of the crown ether coordinated to the metal center forming a 1D polymer strand with a zig-zag pattern. A rotaxane with sulphur atoms on both the wheel and axle resulting in six donors, was synthesized and coordinated to silver(I). The result is a unique interwoven MOF architecture containing a 1D polymer strand connected to a 2D polymer sheet by the interlocked nature of the rotaxane. Chapter 4 takes a look at a pseudorotaxane with two sulphur atoms on the crown ether and one sulphur atom on the axle. This system has the potential to switch to a rotaxane upon the addition of a metal center as both the axle and wheel coordinate to a metal center. The metal center acts as a stopper preventing the individual components from separating. Coordination of the pseudorotaxane to silver(I) was observed through 1H NMR spectroscopy, but a shift in equilibrium occurs as pseudorotaxane formation becomes less favourable. Chapter 5 describes the synthesis of a rotaxane and the resulting coordination of the neutral rotaxane ligand to a range of metals. Coordination to the metal center does occur but in the process the rotaxane becomes protonated. The final chapter summarizes the lessons learned and possible future endeavors.
Frank, Nissa Christina, "New Rotaxane Ligands with Donors on Both the Axle and Wheel" (2016). Electronic Theses and Dissertations. 5635.