Multi-stimuli-responsive tetraphenylethene-based thiazole compound: Time-dependently enhanced blue-shift emission, reversible acidichromism and mechanochromism

Abstract A new tetraphenylethene-based thiazole compound (TPEB-B) was designed and synthesized, which exhibits multi-stimuli-responsive properties and AIE behavior. TPEB-B exhibits dynamic water-stimuli-responsive properties. When large amount of water is injected into the THF solution of TPEB-B (≥70%), the mixture exhibits gradually enhanced blue-shift emission accompanied by emission color changes from weak aquamarine blue to intense blue emission with increasing standing time. Moreover, TPEB-B exhibits reversible acidichromism behavior. When TPEB-B is exposed to trifluoroacetic acid (TFA), the initial blue emission immediately changes into yellowish green emission that will convert back into initial blue emission as it exposed to triethylamine (TEA). In addition, TPEB-B also exhibits reversible mechanochromism. Upon grinding with a pestle, the intense blue emission of TPEB-B transforms into yellowish green emission that will turn into the original blue emission when the ground TPEB-B is fumed with DCM vapor. Such interesting and multi-stimuli-responsive behaviors make TPEB-B a potential material in anti-counterfeiting and other fields.