A new V-shaped 2H-imidazole-based spirocyclic fluorophore: Aggregation-induced emission, twisted intramolecular charge transfer, and high responsiveness to trace water and acid

Design and synthesis of organic solid-state emissive materials have attracted wide attentions due to their potential applications in organic light-emitting diodes (OLEDs), chemo-/bio-sensing, organic lasers, electronic ink, etc. Herein, a V-shaped 2H-imidazole-based spirocyclic fluorophore, DPS-DPA, was efficiently prepared. DPS-DPA shows solvatochromism behaviors. With the continuous addition of anti-solvent water to acetonitrile solution of DPS-DPA, the emission of DPS-DPA first became faint, and then profoundly enhanced, demonstrating the characteristics of twisted intramolecular charge transfer and aggregation-induced emission. To our surprise, the fluorescence of DSP-DPA in solution would be greatly decreased even in the presence of trace amount of water, indicating that DPS-DPA has a high responsiveness to water. Moreover, the emission of DPS-DPA can be quenched by trifluoroacetic acid and recovered after triethylamine addition, realizing reversible fluorescent writing and erasing. Such attributes make the material find wide applications in many areas such as solvent quality control, smart design, and optoelectronic devices.