New machines open up new opportunities for both creating new devices and investigating new problems. Unlike the engineered machines of the industrial age, recent emphasis in chemistry has focused on making molecular machines that operate on the nanometer length scale. Machines at these scales do not operate like their more familiar macroscopic counterparts, but rather like chemical systems. Most of the prior studies have focused on ensuring that the desired motions between two specific locations occur. Relatively little is known about the mechanism of motion between the two locations. In this Thesis, electroanalytical techniques are used to study the rates and mechanism, i.e., pathways, of motion in redox-controlled molecular machines and their prototypes.

The first example of a supramolecular switch that is driven by the reduction of the ligand was discovered. The reduction of bis-bidentate N-heterocyclic ligands provides the driving force for movement of a copper-bound macrocycle between two [2]pseudorotaxanes. Mechanistic studies on this molecular switch revealed that the pathway of motion could be changed when the ligand is reduced. Switching between pathways of motion, e.g., bilability, is expected to play a critical role in the development of unidirectional machines.

While the supramolecular pseudorotaxane switches serve as good models for rotaxanes, they do not capture all of the features of molecular machines. Mechanistic studies on a rotaxane that moves a tetracationic ring (cyclobis(paraquat- p-phenylene) between a redox-active tetrathiafulvalene (TTF) and phenylene station were performed. Kinetic studies on the effects of the linker lengths revealed that longer linkers accelerate the ring's movement away from TTF, but slow its return.

The mechanistic studies on this rotaxane paved the way for creating an autonomous feedback system to regulate the movements of the rotaxane. Automated, robust and environmentally responsive control schemes are required if molecular machines are to fulfill the role of mechanical actuators in robotics system. A closed-loop feedback protocol was established that adjusts pulse durations to maximize the number of rotaxanes that switch forwards and backwards while ensuring stable performance over many cycles and when changing temperatures.

All together, these studies expand the knowledge of how molecular machines move and can be controlled, which opens up the opportunities for more complex and interesting machines in the future.