Molecular Motors in Aqueous Environment

Molecular motors are Nature’s solution for (supra)­molecular transport and muscle functioning and are involved in most forms of directional motion at the cellular level. Their synthetic counterparts have also found a myriad of applications, ranging from molecular machines and smart materials to catalysis and anion transport. Although light-driven rotary molecular motors are likely to be suitable for use in an artificial cell, as well as in bionanotechnology, thus far they are not readily applied under physiological conditions. This results mainly from their inherently aromatic core structure, which makes them insoluble in aqueous solution. Here, the study of the dynamic behavior of these motors in biologically relevant media is described. Two molecular motors were equipped with solubilizing substituents and studied in aqueous solutions. Additionally, the behavior of a previously reported molecular motor was studied in micelles, as a model system for the biologically relevant confined environment. Design principles were established for molecular motors in these media, and insights are given into pH-dependent behavior. The work presented herein may provide a basis for the application of the remarkable properties of molecular motors in more advanced biohybrid systems.