A novel simple red emitter characterized with AIE plus intramolecular charge transfer effects and its application for thiol-containing amino acids detection

Abstract

Developing red fluorescence emitters with simple structures via convenient synthetic routes is highly desirable yet challenging. A novel simple AIE-active red emitter featured with intramolecular charge transfer (ICT) effect was designed by simply integrating common electron donor (D) and acceptors (A) through π bridges, and facilely synthesized via stepwise asymmetric Knoevenagel condensations. Its AIE property comes out from the non-planar 3D configuration and multiple rotors, and the ICT effect is originated from its D–A electronic structure. This aldehyde group-functionalized AIEgen holds the capability to specifically detect thiol-containing amino acids in a light-up fashion with notable blue-shift in fluorescence in 2 min. Dramatic difference in the kinetics enabled this probe to differentiate cysteine (Cys) and homocysteine (Hcy) from glutathione (GSH). More interestingly, it generally shows a higher sensitivity to Hcy over Cys. Moreover, the remarkable fluorescence enhancement when the Cys concentration is above 250 μM and the obvious blue-shift in the UV-Vis absorption spectrum at 15 μM for Hcy reveal the potential of this AIEgen to be applied as an indicator of Cys/Hcy-related diseases.