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2 Movement

Figure 2.11: Controlled movement of a ring of a rotaxane in a specific direction (adapted from [28]).

Figure 2.12: A rotaxane containing two rings (adapted from [29]).

Another group used a pseudo-rotaxane dimer to achieve linear movement in one

molecule [30] (Figure 2.14). Rotaxane dimers including transition metals work by the

same principle ([31] and references therein). Other molecules use light energy to move

the ring.

Another approach is using self-assembling structures to create movement on the

microscale. One example for that is to use interlocking DNA molecules to create tubes in

the range of 0.3–3 µm (Figure 2.15) [32]. The piston that is moving within the tube can be

monitored using fluorescence. Speeds up to 0.3 µm²/s and up to 3 µm total displacements

have been achieved, which is similar to molecular motors.