This paper introduces a novel class of photoswitches, diaryl-hemiindigos (HIs), synthesized through a versatile and easily modifiable method. These chromophores exhibit red-light responsiveness, high thermal bistability, strong isomer accumulations in both switching directions, strong photochromism, tunable acid responsiveness, and acid gating. Their applications are showcased through four-state switching, chemical fueling, and reversible inscription into transparent polymers using light and acid/base stimuli. The study provides a comprehensive photochemical analysis of these compounds, highlighting their potential in various fields, including molecular machines, photoisomerization mechanism studies, and smart materials.

Maximilian Sacherer, Frank Hampel, Henry Dube