Excited State Intramolecular Proton Transfer Plus Aggregation-Induced Emission-Based Diketopyrrolopyrrole Luminogen: Photophysical Properties and Simultaneously Discriminative Detection of Trace Water in Three Organic Solvents.

Developing solid state near-IR (NIR) emitters and simultaneously discriminative detection of trace water in organic solvents has long been a significant challenge. In this work, a novel diketopyrrolopyrrole-based luminogen (DPP1) with excited state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) characteristics has been designed and synthesized. Its amorphous and crystal solids show red and NIR-emissive fluorescence at 625 and 675 nm, respectively. When DPP1 reacts with fluoride anion, the resulting system (DPP1·F) can discriminatively detect the water content in aprotic solvents with colorimetric and fluorescent dual modes. Distinct fluorescent responses of "turn-on", "ratiometric turn-off", and "ratiometric turn-on" and low limits of detection of 0.0064, 0.042, and 0. The water-induced sensitive and fast change in THF was applied to the determination of water in foodstuffs in practical solid state indicator paper strips.