Twelve-membered ring photoswitches with excellent → conversion under ambient light.

Incorporation of azobenzenes into macrocycles is an intriguing approach for fine tuning the photophysical properties of these photoswitches and tailoring them to specific applications. A versatile synthesis of macrocyclic azobenzenes has been developed that allows for facile modification of these photoswitches. One example shows high chemical stability, long half-life of its -isomers, quantitative → conversion under white light, and excellent separation of excitation bands to address either the or -state selectively. The near quantitative → conversion under white light is a unique feature with an important impact on applications, in which the configuration under ambient light needs to be close to 100%.