| While traditional polymer structure is determined by the creation of covalent bonds, the structure of supramolecular polymers (SPs) depends on reversible intermolecular associations such as hydrogen bonding, metal-ligand coordination, and host-guest interactions. The structure and properties of SPs, therefore, depend on the strength and dynamic nature of the associating groups, as well as factors such as monomer concentration and chemical and physical environment. In applications of SPs, it is often the case that these reversible associations bear stress as the SPs interact mechanically with their environment. A complete picture of molecule-to-material relationships in SPs, therefore, should include an understanding of the response of the defining supramolecular interactions to an applied mechanical force.;Single-molecule force spectroscopy (SMFS) provides a useful mechanism through which to probe the mechanics of supramolecular interactions. This thesis describes the application of SMFS to two systems: (1) self-repairing intersurface bridges formed through self-complementary oligonucleotide monomers, and (2) bimolecular ligand substitution reactions. Both the oligonucleotide and the ligand coordination systems are modular and useful for studying structure-property relationships in SPs. We show that SP bridge formation and self-repair in spatially-constrained environments is modulated by a combination of structure and dynamics, and the results agree well with data simulations. Additionally, we report system homology in a series of mechanically-activated bimolecular reactions involving substitution of DMSO for substituted pyridines at a square-planar Pd(II) center. Both sterics at the metal center and nucleophilicity of the leaving group affect the force-induced dissociation, and these effects can be reconciled through comparisons to the stress-free reactions. Finally, a simple and model-independent method for force-induced rate analysis is presented, and its utility and limitations are demonstrated and discussed in the context of both systems. |
