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.