Switched “On” Transient Fluorescence Output from a Pulsed-Fuel Molecular Ratchet
Andrei S. Baluna, Marcel Dommaschk, Burkhard Groh, Salma Kassem, David A. Leigh, Daniel J. Tetlow, Dean Thomas, Loli Varela López
Abstract
High Resolution Image Download MS PowerPoint Slide We report the synthesis and operation of a molecular energy ratchet that transports a crown ether from solution onto a thread, along the axle, over a fluorophore, and off the other end of the thread back into bulk solution, all in response to a single pulse of a chemical fuel (CCl 3 CO 2 H). The fluorophore is a pyrene residue whose fluorescence is normally prevented by photoinduced electron transfer (PET) to a nearby N -methyltriazolium group. However, crown ether binding to the N -methyltriazolium site inhibits the PET, switching on pyrene fluorescence under UV irradiation. Each pulse of fuel results in a single ratchet cycle of transient fluorescence (encompassing threading, transport to the N -methyltriazolium site, and then dethreading), with the onset of the fluorescent time period determined by the amount of fuel in each pulse and the end-point determined by the concentration of the reagents for the disulfide exchange reaction. The system provides a potential alternative signaling approach for artificial molecular machines that read symbols from sequence-encoded molecular tapes.