Self-Tuning of Photoswitching Performance for Non-Cyclic Diarylethenes

Non-cyclic diarylethenes are a very accessible but underappreciated class of photoswitches in terms of their functional applications. The main reason for this is the preconception that successful performance of these molecules as 6π-photoswitches would be hampered by the side Z/E-isomerization. In our work, on a series of novel 2,3-dioxazolylbut-2-enes, we demonstrate that E-isomers of non-cyclic diarylethenes are rapidly eliminated from the system by a “self-tuning” process and do not interfere with efficient two-state photoswitching. In particular, irradiation of E/Z-isomeric mixtures by UV light with subsequent exposure to visible light provides pure Z-isomers of 2,3-dioxazolylbut-2-enes, which further undergo thermally irreversible switching to the closed-ring isomers. This observation perfectly corroborates with some underestimated results from the literature and should bring non-cyclic diarylethenes back into focus as accessible and efficient photoswitches for functional applications in materials chemistry, catalysis and photopharmacology.