From molecular shuttles to directed procession of nanorings

Synthetic molecular shuttles prove that controllable nanoscale translation is possible in the curious shape of molecular rings encircling a linear track. However, a shuttle ring's movement is limited between a pair of binding sites. Ring-locking may provide a molecular mechanism for implementing a major requirement for inchworm nanowalkers. Here we propose a nanowalker in the form of track-encircling molecular rings that is capable of directed procession along an unlimited track beyond molecular shuttles. A detailed molecular design for the walker is obtained by properly exploiting molecular mechanisms already realized in shuttle systems. A computer simulation using realistic parameters predicts major walker-track parameters for optimal performance of the walker. Several unique features of the proposed walker are discussed in comparison with previously suggested or realized motor systems.