Circularly Polarized Luminescence in Rotaxanes and Catenanes

Rotaxanes and catenanes have proven to be key structures in the development of artificial molecular machines with a variety of applications. Among them, the study and modulation of optical properties, mainly light emission, have been widely explored. The growing interest in chiral mechanically interlocked molecules has enabled this research interest to be extended to chiroptical properties, in particular to the study of circularly polarized luminescence. In this review, we discuss the progress on this topic, from seminal examples to the growing number of examples reported in very recent years. Both rotaxanes and catenanes with a fixed or static CPL response are reviewed, but also designs that exploit the switching mechanisms enabled by these interlocked architectures to modulate and switch their CPL response both in solution and/or in the aggregate or solid state.