Design and Synthesis of Donor–Acceptor Stenhouse Adducts: A Visible Light Photoswitch Derived from Furfural

The development of an easily synthesized, modular, and tunable organic photoswitch that responds to visible light has been a long-standing pursuit. Herein we provide a detailed account of the design and synthesis of a new class of photochromes based on furfural, termed donor–acceptor Stenhouse adducts (DASAs). A wide variety of these derivatives are easily prepared from commercially available starting materials, and their photophysical properties are shown to be dependent on the substituents of the push–pull system. Analysis of the switching behavior provides conditions to access the two structural isomers of the DASAs, reversibly switch between them, and use their unique solubility behavior to provide dynamic phase-transfer materials. Overall, these negative photochromes respond to visible light and heat and display an unprecedented level of structural modularity and tunabilty.