Computational, synthetic, and spectroscopic investigations of molecular switches, their effects on pendant groups, and their abilities to form and affect measurable changes in supramolecular assemblies

The use of switchable molecules to modulate properties of pedant groups to affect a measurable change was investigated. A survey of the literature identified many switchable systems, induced by stimuli such as light, heat, electrical current, and/or mechanical stress. Light is easily tuned and readily available, so photoswitchable systems were chosen to study. Switchable systems that could be synthesized in relatively few steps and could be incorporated into groups that showed precedence for interacting with other species were proposed. These groups include amidines and aminopyridines, which can be used as ligands in metal complexes when deprotonated, and squaramides, which are well known to participate in hydrogen-bonding and ion-binding. Substituents known to participate in halogen- and pnictogen-binding were also studied. The ability of switchable moieties to modulate changes in the redox properties and electrostatic potentials as they relate to halogen bond and pnictogen bond donor ability was investigated computationally. For compounds that were successfully synthesized, experimental and computational results correlate well. This modulation of pendant groups has potential applications in light harvesting and stimulus responsive supramolecular assemblies.