A novel hydroxyl-containing polyimide as a colorimetric and ratiometric chemosensor for the reversible detection of fluoride ions

A novel hydroxyl-containing polyimide ( PI-OH ) has been successfully synthesized and subsequently used as a new colorimetric and ratiometric chemosensor for the detection of F − with high selectivity and a fast response time. The ratiometric absorbance changes of the chemosensor PI-OH in DMSO solution show a linear response to F − in the concentration range of 0-0.50 mM with a detection limit of 1.79 μM, which provides a quantitative method for F − detection. 1 H NMR titration and DFT calculation studies confirm the F − sensing mechanism involves H-bond interactions and subsequent deprotonation in the chemosensor. Moreover, the chemosensor PI-OH in DMSO solution can be reversed many times and applied to the visual detection of F − . Finally, PI-OH film has been fabricated for real-time visualization of F − with high selectivity and sensitivity. The F − bonded to the PI-OH film can be easily removed by immersing it in acidic solution to recover the sensing ability to F − . X-ray photoelectron spectroscopy and energy dispersive spectroscopy analysis indicate that hydroxyl groups in the PI-OH film can bond to F − and the bonded F − can be removed quantitatively. This work provides not only a novel PI film-based sensor device for the visual and reversible detection of F − with high-efficiency, but also a promising F − extractor. A novel hydroxyl-containing polyimide film has been designed and fabricated as a chemosensor for the real-time visualization of F − with high selectivity and sensitivity.