The chemistry of rotaxanes will be pursued. Rotaxanes are supramolecules in which a bead is threaded by a linear subunit. Bead dissociation is sterically prevented by two bulky groups (stoppers) attached to both ends of the linear subunit. A substantial portion of this work will be done with rotaxanes in which cyclodextrins are used as the beads. This project will investigate the nature of the fundamental interactions leading to self-assembly of cyclodextrin-based ?3!rotaxanes and ?4!rotaxanes, structures with either two or three cyclodextrin beads, respectively. In a second aspect of the work, rotaxanes will be synthesized where the cyclodextrin bead completely encapsulates a redox-active group. These systems will allow an evaluation of the importance of solvent reorganization in electron transfer reactions. The third aspect of the work will investigate the possibility of electrochemically controlling the position of an electron acceptor bead encapsulated on a thread with two different donor stations. %%% This grant from the Organic Dynamics Program supports the work of Professor Angel K. Kaifer at the University of Miami. Large molecular systems will be prepared that are composed of a bead molecule which encapsulates a linear string molecule. Bulky groups will be placed at the ends of the string to prevent dissociation of the bead. The assembly process to form these large molecular systems will be studied. A particular portion of the string will be oxidized to generate a positive charge and the effect of the bead on this process will be evaluated in the context of solvation. Control of the movement of the bead along the string by oxidizing or reducing different stations on the string, and thereby changing charge at these stations, will be studied.
