Synthesis of a Series of 12-Membered Azobenzene Macrocycles and Tuning of the Half-Life of the Thermal Z - E Isomerization.

Azobenzene macrocycles (AzMs) represent a class of azobenzene that are typically photoswitchable with good switching yields of E and Z isomers at certain photostationary states. Here, the synthesis and versatile functionalization of 12-membered AzMs is presented to obtain various meta - and para -aryl-substituted AzMs in high yields of 71-98%. At different positions in the periphery, these substituents significantly impact on the thermal half-lives of the less-stable Z isomers. Para -substitution leads to faster thermal relaxation than meta -substitution, and electron-donating groups lead to a faster relaxation than electron-withdrawing groups.