Stimuli-ControlledKeto–Enol Tautomerism ofExtended Unsaturated Carbonyls for Gating Photoswitching of Diarylethenes

Gated photoswitching systems, which enable control over photochromic properties, play an important role in chemistry. Here, we present a novel gated system based on extended unsaturated 1,3-dicarbonyl derivatives of diarylethenes by manipulating keto–enol tautomerism. While the intramolecular charge transfer process blocked the photochromism, the creation of an ester enabled efficient bidirectional photoswitching. The use of acid/base further induced a shift of the keto–enol equilibrium. Finally, switchable multistep gating control of the photochrome was achieved, enhancing the complexity.