Designing P-type bi-stable overcrowded alkene-based chiroptical photoswitches

Overcrowded alkene based molecular motors and switches constitute a unique class of photo-responsive systems due to their intrinsic chirality near the core C(sic )C bond, making them highly suitable candidates for the construction of light-switchable dynamic systems, i.e., for controlling molecular motion, modulation of material chiroptical properties and supramolecular assembly. However, the lack of general design principles, along with the challenging synthesis of these molecules, precludes full exploitation of their dynamic structures. Therefore, systematic investigations of the key parameters are crucial for the further development of these systems. Here we provide a facile alternative synthetic route, elucidate the influence of substituents on the photochemistry of overcrowded alkene-derived bistable chiroptical photoswitches, and show nearly quantitative bidirectional photoswitching. The established structure-property relationship constitutes a practical guideline for the design of these photochromes tailored to a specific application.

Automated summary

Overcrowded alkene based molecular motors and switches, due to their intrinsic chirality near the core CC bond, are highly suitable for constructing light-switchable dynamic systems. However, the lack of design principles and challenging synthesis hinders their full exploitation. Therefore, systematic investigations of key parameters are crucial for further development. This study provides an alternative synthetic route, elucidates the influence of substituents on the photochemistry, and establishes a structure-property relationship for tailored design of photochromes.