Interactions-stabilized metastable trans-isomers and force-induced ESIPT release

Cis/trans isomerization is a candidate for immense fields, especially metastable states offering distinctive properties that arouse wide interests, but their stabilization remains challenging. We report a novel strategy to stabilize the thermodynamically metastable trans-isomers of 2-(2′-hydroxyphenyl)-4,5-diphenylimidazole (HDPI) derivatives, by introducing multiple intermolecular interactions. The TPE-HDPI compound with tetraphenylethylene (TPE) moiety promoted abundant intermolecular interactions to form trans-isomers in crystals, as confirmed by crystal and Hirschfeld surface analysis. The grinding-induced ESIPT release phenomenon observed by TRES spectra provides evidence for the transformation from the trans- to the cis- configuration.