Incorporating a steric barrier between the two stations in a bistable [2]rotaxane based on monopyrrolotetrathiafulvalene and cyclobis(paraquat-p-phenylene) allows the high-energy metastable-state co-conformation to be physically isolated following a single redox cycle, thus making it possible to store energy (4.4 J L-1) and to follow its interconversion back to the ground-state co-conformation.