Design and Synthesis of AIE-Based Small-Molecule and Nanofibrous Film for Fluorescent Sensing Application

Abstract

Fluorescent sensors that respond to environmental conditions (temperature, pressure, and pH) have attracted widespread attention in recent years. Generally, traditional solid-state fluorescent materials tend to suffer from aggregation-induced quenching (ACQ) and difficulty of film forming, limiting their extensive applications. Therefore, researchers are focusing more and more attention on fluorescent sensors with aggregation-induced emission (AIE) effects. Herein, the article reports an AIE molecule (TPEBZMZ) containing tetraphenylethylene (TPE) and benzimidazole fragments. The fluorescence properties of TPEBZMZ in solution and aggregation states have been investigated, and the luminescence performance and aggregation structures of solid-state TPEBZMZ after force and acid treatments have been explored. The results show obvious AIE and fluorescent sensing properties of TPEBZMZ, presenting force- and acid-induced discolorations. Moreover, the TPEBZMZ-based fluorescent nanofibrous film is fabricated by electrospinning the solution of TPEBZMZ blended with polylactic acid (PLA), which shows a good nanofiber film structure and exhibits reversible acid-induced discoloration property, even with only 0.5 wt% TPEBZMZ. This work provides a simple strategy to achieve stimulus-responsive fluorescent film.

Multistimuli‐responsive fluorescence behaviours of aggregation‐induced emission small‐molecule and electrospun nanofibre films for acid–base vapour sensing

“…Eventually, the fluorescence intensity increased 18‐fold at an f w of 90% compared with that in pure THF (Figure 1b). These results indicated that compound TPECNPy‐2 formed nanoparticle aggregates in a poor solvent system, as proven by the level‐off tail phenomenon in the UV–vis absorption spectra of TPECNPy‐2 (Figure S6a) when f w exceeded 70% [26], and exhibited excellent AIE abilities. Similarly, compound TPECNPy‐3 also showed a good AIE effect (Figure 1c and Figure S6b).…”

“…4‐(1,2,2‐Triphenylethenyl)benzaldehyde (TPECHO) was synthesized in the laboratory according to published literature [26]. 2‐Pyridylacetonitrile (98%), 3‐pyridineacetonitrile (98%) and tetrabutylammonium hydroxide (TBAOH, 0.8 M in methanol) were acquired from Shanghai Aladdin Biochemical Technology Co., Ltd. Cellulose acetate (39.8 wt% acetyl and 3.5 wt% hydroxy) was supplied by Aladdin.…”

“…Therefore, introducing some unique functional groups into AIE-based molecules can endow them with increased stimuli responsiveness, except responsiveness to aggregation and mechanical force, therefore serving as an efficient way to develop more multistimuli-responsive fluorescent materials [23][24][25][26][27][28]. For example, introducing alkaline or acidic groups, such as benzimidazole [26], benzothiazole [24], and hydroxy [23], groups, into AIE-based molecules results in additional pH stimulus-responsive characteristics. As another example, the borate ester group was introduced into mechanochromic AIE-based molecules, resulting in a fluorescent sensing ability for ClO À recognition [28].…”

“…An alternative solution is to fabricate fluorescent nanofibre films mixed with AIE-based small organic molecules using electrospinning [26,29], because this is a widely used scalable technique for the preparation of nanofibre films with high specific surface area and porosity [26,32,33]. Electrospun nanofibre films for fluorescent sensing have been shown to improve the sensitivity and response rate and have therefore received considerable attention [34].…”

Fibrous aggregates: Amplifying aggregation-induced emission to boost health protection

“…However, most of the existing molecular probes have been dispersed in biological fluids for working, which are not suitable for visual and portable detection. Fibers (especially electrospun nanofibers), characterized by high surface-area-to-volume ratios, are attractive candidates to combine with AIEgens for constructing sensors with high sensitivities, rapid responses, and great simplicity [ 38 , 39 ]. AIE probes are integrated with fibers for sensing in two forms, one is directly doping into fibers, another is grafting onto the surface of fibers.…”