All chemists are familiar with the idea that, at equilibrium
steady
state, the relative concentrations of species present in a system
are predicted by the corresponding equilibrium constants, which are
related to the free energy differences between the system components.
There is also no net flux between species, no matter how complicated
the reaction network. Achieving and harnessing non-equilibrium steady
states, by coupling a reaction network to a second spontaneous chemical
process, has been the subject of work in several disciplines, including
the operation of molecular motors, the assembly of supramolecular
materials, and strategies in enantioselective catalysis. We juxtapose
these linked fields to highlight their common features and challenges
as well as some common misconceptions that may be serving to stymie
progress.