Structural control at the organic–solid interface

The structure–function relationships of a series of bistable [2]rotaxane and [2]pseudorotaxanebased devices have been evaluated across different length scales. The switching characteristics of bistable [2]rotaxanes and self-assembled [2]pseudorotaxanes, which can be controlled chemically, electrochemically, or photochemically, enable them to function as prototypes of molecular machines. The switching processes are operative, not only in solution, but also in a wide variety of condensed phases. The universality of the switching mechanism demonstrates that these functional organic materials can be incorporated onto solid metallic and inorganic supports for device applications, despite the fact that interactions at the organic substrate interface can influence molecular structure and function. Through iterative design–analysis feedback loops that focus upon fine-tuning device performance, based on molecular structures and molecule-substrate interactions, the fabrication of functioning micro-actuators, nanovalves and light-harvesting devices has been achieved.