Thus, the mechanical motion in 11 is not formally coupled to the conversion of 12H to 13H. Unlike in the case of information ratchet 6, the maximum work that motor 11 can perform per cycle is not a function of the overall free energy change associated with this process (Box 2); the maximum work that can be performed at each stage of the cycle is simply determined by the energetic difference between the two co-conformations, as it is if 11 is operated by simple addition of acid followed by base (see ESI). Indeed, the operation of switches and energy ratchet motors such as 11 using reagents that change the properties of the system (e.g., pH) in a time dependent manner but whose reaction is not coupled to the network, is conceptually identical to the simple addition of one reagent (e.g., HCl) followed by a counteracting other (e.g., NEt3). 27 Summary. Although coupling a spontaneous process to a reaction network to generate a non-equilibrium steady state has a very different objective in the case of synthesis (distort concentrations of key species) than in the operation of molecular motors (escape detailed balance), the principles are identical. Information motors have been shown to generate continuous net directional motion if the coupled reaction is spontaneous. As well as being elegant examples of prototypical molecular machines, albeit they have yet to be harnessed to do work, 8 synthetic molecular motors can provide a tractable platform to explore concepts related to biological molecular motors, such as ATP-synthase, which operate according to the same principles. However, even in relatively simple systems, ambiguity can arise; the detail of the reaction network and associated mechanism and kinetics are important. Finally, although a cyclic reaction network coupled to the spontaneous reaction is required to drive continuous repetitive motion, the motion itself need not be cyclic. For example, Leigh and co-workers have demonstrated a prototypical system that could operate as a linear motor but whose behavior also relies on a cyclic reaction network, as do the operation of linear biological motors such as kinesin. The assembly of small molecules to generate supramolecular polymers takes place reversibly to give a thermodynamically favorable assembly. This general principle has been used to create a wide range of structures based on various non-covalent interactions, including H-bonding, - interactions, metal-ligand interactions, and host-guest chemistry, for a range of proposed applications. 31 In all cases, an equilibrium steady state is achieved in which there is no net flux between the molecules in solution and the aggregate. As with simple molecular switches, it is possible to switch supramolecular polymers between different states by varying the conditions or applying other stimuli. Once again, although at the point of switching the system is away from equilibrium, over time a new equilibrium state is reached.