A recognition-gated azobenzene photoswitch

Abstract

We describe a push–pull azobenzene derivative whose photoswitching can be regulated by molecular recognition. Complexation of the tetra-amide receptor with a Hg²⁺ ion blocks an intramolecular charge transfer (ICT) excited state, thereby gating the population of a π–π* excited state, which is responsible for the photoswitching.