Facile fabrication of a fluorene-containing polyimide film-based fluorescent sensor for rapid and selective detection of fluoride ion

作者：Wu, Yancheng^*; Liu, Shumei; Zhao, Jianqing

来源：Journal of Photochemistry and Photobiology A: Chemistry , 2022, 425: 113728.

DOI：10.1016/j.jphotochem.2021.113728

• Fluorescent polyimide
• Post-polymerization modification
• Film-based fluorescent sensor
• Fluoride ion
• High selectivity
• Fast response

A fluorene-containing polyimide (PI) with tert-butyldimethylsiloxy (TBS) side groups (PI-TBS) was designed and readily prepared by a post-polymerization modification on hydroxyl-containing PI. When the electron-donating hydroxyl groups in PI chain are replaced with bulky non-polar TBS side groups, inter-chain charge transfer effect of the modified PI-TBS is effectively weakened, finally resulting in the fluorescent characteristic of PI-TBS. The as-obtained fluorescent PI-TBS film-based sensor for detection of fluoride ion (F-) displays the remarkable fluorescence quenching with a short response time and high selectivity over other coexistent anions, when PITBS film was immersed in the fluoride-containing solution. Moreover, after immersing in the fluoride-containing solution, the PI-TBS film shows a naked-eye visible color change to yellow-green from light yellow under daylight and an obvious fluorescence quenching under 365 nm UV light. The energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopic (XPS) analyses and density functional theory (DFT) calculation studies indicate that the selective fluoride-induced cleavage of the Si-O bond enhances the intramolecular charge transfer (ICT) in PI chains, leading to fluorescence quenching. This work provides a direct polymer filmbased fluorescent sensor device for the fast, selective and naked-eye visible detection of F- .