Coupled linear and rotary motion in supramolecular helix handedness inversion

We report on a remarkable pathway for the inversion of handedness in a model supramolecular helix that exhibits repeated extension and contraction coupled with correlated rotation. The pathway involves a boundary between two segments of opposite handedness, which propagates along the helix through a hopping mechanism, causing periodic opening and closing of a gap between the two segments, while they rotate cooperatively in opposite directions. While the hopping mechanism is likely to have wider implications for reversal of helix handedness in general, the existence of such a pathway suggests the possibility of designing a novel class of nanoscale machines exploiting helix handedness inversion.