Date of Award

1-27-2016

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry and Biochemistry

First Advisor

Loeb, Stephen

Rights

CC BY-NC-ND 4.0

Abstract

This thesis presents the design, synthesis and characterization of [2]rotaxane, [2]pseudorotaxane and [3]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 [2]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 [2]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 [2]rotaxane. Chapter 4 takes a look at a [2]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 [1]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 [2]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 [3]rotaxane and the resulting coordination of the neutral [3]rotaxane ligand to a range of metals. Coordination to the metal center does occur but in the process the [3]rotaxane becomes protonated. The final chapter summarizes the lessons learned and possible future endeavors.

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