Star-Shaped ESIPT-Active Mechanoresponsive Luminescent AIEgen and Its On-Off-On Emissive Response to Cu/S.

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 ( ) conjugate from simple precursors triaminoguanidine hydrochloride and 4-(,-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 was established in the CHCN/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 . In addition, selectively sensed a Cu ion through a colorimetric and fluorescence "turn-off" route, and subsequently, the -Cu ensemble could act as a selective and sensitive sensor for S in a "turn-on" fluorescence manner via a metal displacement approach. Reversible "turn-off-turn-on" features of with Cu/S ions were efficiently demonstrated to construct the IMPLICATION logic gate function. The Cu/S-responsive sensing behavior of was established in the paper strip experiment also, which can easily be characterized by the naked eye under daylight as well as a UV lamp (λ = 365 nm).