Motional modes 2 catenanes

Fig. 8. Building blocks and motional modes in a [2]catenane. (a) Rigid and flexible building blocks of a spin-labeled macrocycle, (b) Schematic structure of the singly labeled [2]catenane and types of motions, (c) Schematic structure of the spin-labeled macrocycle, (d) Schematic structure of the spin-labeled rigid part of the macrocycle.

Another area of NEMS that is receiving tremendous attention is the mimicry of biological systems, aptly referred to as biomimetics. For instance, in the development of linear molecular muscles that undergo contraction and extension movements. Initial work in this field utilized transition metal complexes containing rotaxanes and catenanes, due to the nondestructive redox processes occurring on the metal centers.Though these complexes were actuated by a chemical reaction, the movement was in a noncoherent manner. In order to better mimic skeletal muscle movement, one has to look at the mode of motion within the most efficient molecular machines - in our human bodies. 

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