Multi-stimuli-responsive cyanostilbene derivatives: Their fluorescent and mechanochromic properties, and potential application in water sensing and anti-counterfeiting.

In recent years, aggregation-induced emission luminogens (AIEgens) have witnessed numerous groundbreaking advances in fundamental theoretical research and functional applications. Notably, stimuli-responsive AIEgens have achieved remarkable results, demonstrating immense potential for application in various fields such as chemistry, materials science, biology, and medicine. Herein, two multi-stimuli-responsive cyanostilbene derivatives TPE-CNTPA and PH-CNTPA were synthesized by introducing tetraphenylethylene (TPE) and trifluoromethyl groups, respectively. Primarily, under the combined mechanism of aggregation-induced emission (AIE) and twisted intramolecular charge transfer (TICT), TPE-CNTPA and PH-CNTPA exhibit "on-off-on" fluorescent emission characteristics in solution. Secondly, under 365 nm ultraviolet light irradiation, the photo-induced isomerization of PH-CNTPA causes changes in photophysical property, demonstrating its responsiveness to ultraviolet light. In addition, TPE-CNTPA and PH-CNTPA exhibit high-contrast mechanochromic properties, providing broader possibilities for their potential applications in various fields. Moreover, owing to the unique fluorescence emission characteristics, TPE-CNTPA and PH-CNTP have enormous potential for application in the field of encryption anti-counterfeiting. Besides, PH-CNTPA can be utilized for the detection of trace water in single or mixed solvents, demonstrating outstanding sensitivity and anti-interference properties in different solvents. This research work reveals the potential in the fields of water sensing and anti-counterfeiting for these two multi-stimuli-responsive compounds.