Twelve-membered ring photoswitches with excellent Z → E 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 Z -isomers, quantitative Z → E conversion under white light, and excellent separation of excitation bands to address either the E or Z -state selectively. The near quantitative Z → E 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%.