An Intelligent AIEgen with Nonmonotonic Multiresponses to Multistimuli

• Published in: Advanced science Vol. 7; no. 20; pp. 2001845 - n/a
• Main Authors: Tu, Yujie, Yu, Yeqing, Xiao, Diwen, Liu, Junkai, Zhao, Zheng, Liu, Zhiyang, Lam, Jacky W. Y., Tang, Ben Zhong
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01-10-2020; John Wiley and Sons Inc; Wiley
• Subjects: aggregation‐induced emission; albumin sensing; amine gas sensing; nonmonotonic multistimuli responses; Solvents; Trends; white‐light emission; aggregation‐induced emission; albumin sensing; nonmonotonic multistimuli responses; amine gas sensing; white‐light emission
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202001845

Intelligent stimulus–response (S/R) systems are the basis of natural process and machine control, which are intensively explored in biomimetic design and analytical/biological applications. However, nonmonotonic multi‐S/R systems are still rarely studied so far. In this work, a rational design strategy is proposed to achieve such a unique S/R system by integrating opposite luminescence behaviors in one molecule. When solvent polarity increases, many heterocyclic or carbonyl‐containing compounds often become more emissive due to the suppression of the proximity effect, whereas molecules with donor–acceptor (D–A) structures tend to be less emissive because of the twisted intramolecular charge transfer. Meanwhile, protonation on D/A moieties will weaken/strengthen the D–A interaction to result in blue/redshifted emissions. By combining a protonatable heterocyclic acceptor and a protonatable donor together in one molecule, nonmonotonic brightness responses to polarity stimuli and nonmonotonic color responses to pH stimuli can be achieved. The design strategy is successfully verified by a simple molecule named 4‐(dimethylamino)styryl)quinoxalin‐2(1H)‐one (ASQ). ASQ exhibits nonmonotonic responses to polarity and pH stimuli, and aggregation‐induced emission (AIE) with a nonmonotonic AIE curve. Meanwhile, ASQ can be adjusted to emit white light in an acidic environment, and it shows multivalent functionalities including albumin protein sensing, ratiometric pH sensing, and amine gas sensing.
Nonmonotonic multistimuli responsive systems are rarely reported. Now, an intelligent AIEgen is developed to show a nonmonotonic brightness response to solvent polarity, and a nonmonotonic color response to solution acidity. Meanwhile, it can serve as a white‐light emitter and a sensor for the detection of albumin, amine gas, and pH.