Water-stimuli-responsive dynamic fluorescent switch from Kasha ' s rule to anti-Kasha ' s rule based on a tetraphenylethene substituted Schiff base

Stimuli-responsive fluorescence switches have aroused enormous interest due to their wide prospects in dealing with safety, health, energy, etc. However, most stimuli-responsive fluorescent switches usually follow the Kasha's rule and are static responsive, which cannot utilize high-energy excited states and provide relatively unitary luminescent signal limiting their wider applications. Herein, a tetraphenylethene-substituted Schiff base (TPENOCN) was synthesized, which exhibited expectedly water-induced fluorescent switch from Kasha's rule emission to anti-Kasha's rule emission accompanied by dynamic emission color changes from yellow to blue with an enhanced fluorescent quantum yield. Theoretical and experimental investigations revealed that the dynamic fluorescent switch is induced by the gradually formation of intermolecular hydrogen bond between TPENOCN and water. Furthermore, an eco-friendly rewritable paper for security writing/printing, multilevel anti counterfeiting and data storage were developed by employing TPENOCN as imaging layer and water as ink. The unique water-stimuli-responsive characteristics of TPENOCN with dynamic emission changes may have promising application in data security, data protection, fluorescence detection and so on.

Automated summary

The synthesized TPENOCN can achieve dynamic fluorescence switching induced by water, with potential applications in data security and anti-counterfeiting.