Helicenes as Chiroptical Photoswitches

In this Concept Article, we analyze known helicene systems that function as chiroptical photoswitches from a stereochemical perspective and classify them based on the type of transformation of the helicene core that takes place during the switching process. In every case, we inspect the stereodynamics of each of the two forms of the switch and the stereospecificity of their interconversion, and we discuss the chemical working principles and chiroptical responses of the switches. We hope that our analysis will motivate the design of new types of helicene photoswitches to expand the structural diversity of this, at present rare but beautiful, class of compounds.