Star-Shaped ESIPT-Active Mechanoresponsive LuminescentAIEgen and Its On–Off–On Emissive Response to Cu 2+ /S 2–

Design and development of multifunctional materials have drawn incredible attraction in recent years. Herein, we report the design and construction of versatile star-shaped intramolecular charge transfer (ICT)-coupled excited-state intramolecular proton transfer (ESIPT)-active mechanoresponsive and aggregation-induced emissive (AIE) luminogen triaminoguanidine-diethylaminophenol (LH3) conjugate from simple precursors triaminoguanidine hydrochloride and 4-(N,N-diethylamino)salicylaldehyde. Solvent-dependent dual emission in nonpolar to polar protic solvents implies the presence of ICT-coupled ESIPT features in the excited state. Aggregation-enhanced emissive feature of LH3 was established in the CH3CN/water mixture. Furthermore, this compound exhibits mechanochromic fluorescence behavior upon external grinding. Fluorescence microscopy images of pristine, crystal, and crushed crystals confirm the naked-eye mechanoresponsive characteristics of LH3. In addition, LH3 selectively sensed a Cu2+ ion through a col...