Figure 17.

Illustration of a molecular demon that selectively shepherds a ring in an intermediate state to assemble rather than disassemble even though the assembled state is higher in energy. The demon can operate either as a blind energy ratchet (Smoluchowski demon), raising and lowering the energies of states and barriers irrespective of the state of the molecule, or as a sighted information ratchet (Maxwell demon), raising and lowering barriers depending on the state of the molecule. The design principles necessary for synthetic implementation of the two types of “demons” are very different.[10,49]