Light-driven molecular machines based on ruthenium(II) polypyridine complexes: Strategies and recent advances

Multicomponent molecular systems that exhibit large amplitude movements controlled by external inputs – namely, molecular machines – are extensively investigated both for their basic science interest and for their potential applications in technology and medicine. Light is a convenient stimulus to operate molecular machines because it can provide both an energy supply to feed their motion and an analytical signal to monitor their state. Research in the past two decades has shown that the unique and highly tunable structural, photophysical, photochemical and redox properties of Ru(II) polypyridine complexes are advantageous tools for implementing a light-induced response in molecular devices and machines. Here we describe the latest progresses in the realization of artificial nanoscale machines that use such metal complexes to process light signals. We will show the level of creativity and sophistication reached in this research area by describing a few selected examples.