A <i>tert</i>-Butyldiphenylsilyl-Containing Polyimide-Based Chemosensor for Sequential Detection of Fluoride Ions and Trace Water in Organic Solvents

• Published in: Molecules
• Main Authors: Yancheng Wu, Manyu Lian, Guotao Huang, Yangfan Zhang, Ningbo Yi, Liyong Tian, Feng Gan, Chunping Ma
• Format: Article
• Language: English
• Published: MDPI AG 2023-12-01
• Subjects: <i>tert</i>-butyldiphenylsilyl-containing polyimide; colorimetric and ratiometric chemosensor; fluoride ions; trace water
• Online Access: https://www.mdpi.com/1420-3049/28/24/7987
• ISSN: 1420-3049

A <i>tert</i>-butyldiphenylsilyl-containing polyimide (<b>PI-OSi</b>) has been established as a colorimetric and ratiometric chemosensor for rapid detecting fluoride ions (F⁻). The UV-vis absorbance ratio value (A₃₂₂/A₂₈₈) of <b>PI-OSi</b> in a DMF solution displays a wide linear range change to F⁻ concentrations with a detection limit (DL) value of 2.13 μM. Additionally, adding incremental amounts of F⁻ to a DMF solution of <b>PI-OSi</b> shows an immediate color change to yellow and finally to green from colorless. More interestingly, the resulting <b>PI-OSi</b> plus F⁻ system (<b>PI-OSi</b>·F) could detect trace water in DMF. The A₂₉₂/A₃₂₂ value of <b>PI-OSi</b>·F almost linearly increases with low water content, which suggests convenient quantitative sensing of trace water content in DMF. The DL value of <b>PI-OSi</b>·F for sensing water in DMF is determined to be 0.00149% (<i>v</i>/<i>v</i>). The solution color of <b>PI-OSi</b>·F returns to colorless when the water content increases, indicating that <b>PI-OSi</b>·F can conveniently estimate water content in DMF by naked-eye detection. The detection mechanisms confirmed by an ¹H NMR study and a DFT calculation involve a F⁻-induced desilylation reaction of <b>PI-OSi</b> to form phenolate anion followed by protonation with trace water. Finally, <b>PI-OSi</b> film was fabricated for the colorimetric detection of F⁻ and water in CH₃CN.