Anomalous photochromism and mechanochromism of a linear naphthopyran enabled by a polarizing dialkylamine substituent

• DOI: 10.1039/d3sc03790h
• Publication Date: 2023-09-04T16:41:52Z
• Authors: Yan Sun; Molly E. McFadden; Skylar K. Osler; Ross W. Barber; Maxwell J. Robb
• Keywords: Merocyanine

In contrast to common angular naphthopyrans that exhibit strong photochromic and mechanochromic behavior, constitutionally isomeric linear are typically not photochromic, due the putative instability of completely dearomatized merocyanine product. The photochemistry is thus relatively understudied compared naphthopyrans, while mechanochromism remains unexplored. Here we demonstrate incorporation a polarizing dialkylamine substituent enables behavior from polymers containing novel naphthopyran motif. solution phase experiments, Lewis acid trap was necessary observe accumulation product upon photochemical ultrasound-induced mechanochemical activation. However, same molecule incorporated as crosslinker in polydimethylsiloxane elastomers renders materials without addition any trapping agent. This study provides insights into reactivity have conventionally been considered functionally inert, adding new class molecular switches repertoire stimuli-responsive polymers.