Aggregation-induced emission luminogens (AIEgens) have attracted extensive interest for their outstanding luminescence properties in the aggregated state and even in the solid state. In this work, we developed a series of novel AIEgens based on 2,5-bis(4-alkoxycarbonylphenyl)-1,4-diaryl-1,4-dihydropyrrolo[3,2-b]pyrrole (AAPP). The AIEgens can be facilely synthesized through a single-step reaction under mild conditions with satisfactory yields. Interestingly, AAPP was found to have multiple luminous mechanisms that result in variable fluorescence properties. The propeller-like structure of AAPP enables a restricted intramolecular rotation (RIR) process which significantly enhances its fluorescence in the aggregated state (i.e. AIE fluorescence). In addition, there is a donor–acceptor interaction between the heterocycle center and the alkoxycarbonyl units in AAPP which allows a typical twisted intramolecular charge transfer (TICT) process in the dispersed state, resulting in strong fluorescence emissions in non-polar or low-polarity solvents but fluorescence quenching in high-polarity solvents. Due to the tunable RIR and TICT processes and the multiple fluorescence, AAPP compounds exhibit multifunctional applications: (1) as a reversible fluorescent thermometer, AAPP exhibited excellent fatigue resistance. There was a good linear relationship between its fluorescence intensity and temperature from 10 °C to 60 °C. (2) The desethyl AAPP derivative (CAPP) was successfully applied in the detection of Cd(II) in aqueous solution at neutral pH, and showed a 500-fold fluorescence “turn-on” response to Cd(II) with good selectivity.

中文翻译：

---

2,5-双（4-烷氧基羰基苯基）-1,4-二芳基-1,4-二氢吡咯并[3,2- b ]吡咯（AAPP）AIEgens：可调RIR和TICT特性及其多功能应用

聚集诱导的发光致发光剂（AIEgens）因其在聚集状态甚至固态下的出色发光性能而引起了广泛的关注。在这项工作中，我们开发了一系列基于2,5-双（4-烷氧基羰基苯基）-1,4-二芳基-1,4-二氢吡咯并[3,2- b ]吡咯（AAPP）的新型AIEgens 。AIEgens可以在温和的条件下通过一步反应轻松合成，并具有令人满意的收率。有趣的是，发现AAPP具有多种发光机制，从而导致可变的荧光特性。AAPP的螺旋桨状结构可实现受限的分子内旋转（RIR）过程，从而在聚集状态下显着增强其荧光（即AIE荧光）。此外，AAPP中的杂环中心与烷氧羰基单元之间存在供体-受体相互作用，这使分散状态下的典型扭曲分子内电荷转移（TICT）过程成为可能，从而在非极性或低极性下产生强荧光发射溶剂，但在高极性溶剂中进行荧光猝灭。由于RIR和TICT的可调过程和多种荧光，AAPP化合物具有多种用途：（1）作为可逆荧光温度计，AAPP具有出色的抗疲劳性。其荧光强度与10°C至60°C的温度之间存在良好的线性关系。（2）脱乙基AAPP衍生物（CAPP）在检测镉（的成功地应用于II中，在中性pH的水溶液），并表现出500倍荧光“接通”响应于镉（II具有良好的选择性）。