Selective switching of multiple azobenzenes

Chem Sci. 2019 Jun 21;10(31):7418-7425. doi: 10.1039/c9sc02347j. eCollection 2019 Aug 21.

Abstract

Multi-state photoswitchable compounds are highly attractive for application in data storage or multi-responsive materials. In this work, a trisazobenzene macrocycle capable of three-state isomerization is presented. The compound can be switched into each of the states with more than 70% of the isomer solely by light and heat as stimuli representing the first example for an oligo-azobenzene containing identical photochromic units which can be selectively adressed. Detailed spectroscopic, crystallographic, HPLC as well as computational investigations and the comparison to a less and a higher strained derivative revealed macrocyclic ring strain to be responsible for the compounds unique isomerization behavior.