| Diffusion ordered 2D NMR spectroscopy (2D DOSY) is a powerful non-invasive method to determine self-diffusion coefficients. Polyrotaxanes are macromolecules threaded with macrocycles. These supramolecular assemblies exhibit novel properties due to their unique architecture. In this dissertation, DOSY and polyrotaxanes are brought together. The research is divided into two closely related parts: (1) Determine the influence of rotaxane architecture on its properties using NMR techniques. A series of poly(ethylene glycol)-rotaxa-alphaCD's (PEG-rotaxa-alphaCD) were synthesized. The dilute-solution properties of PEG-rotaxa-alphaCD were explored using 2D DOSY and its properties are found to be similar to the corresponding PEG. (2) Explore and develop new DOSY techniques for rotaxane characterization. By exploring the distinct diffusion behavior of the threaded and free macrocycles, DOSY is demonstrated to be a valuable tool for the general purpose of (a) definitive proof of threading, and (b) quantification of threaded and unthreaded fractions. New pulse sequences were successfully developed for (a) improved convection compensation in diffusion measurements, (b) improved filtering of carbon resonances according to the number of attached protons, and (c) diffusion measurements in complex mixtures that contain overlapping resonances from separate components. While these new sequences were developed for use in polyrotaxane characterization, they should indeed enjoy widespread application. |
