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

Atert-butyldiphenylsilyl-containing polyimide (PI-OSi) has been established as a colorimetric and ratiometric chemosensor for rapid detecting fluoride ions (F−). The UV-vis absorbance ratio value (A322/A288) ofPI-OSiin 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 ofPI-OSishows an immediate color change to yellow and finally to green from colorless. More interestingly, the resultingPI-OSiplus F−system (PI-OSi·F) could detect trace water in DMF. The A292/A322value ofPI-OSi·F almost linearly increases with low water content, which suggests convenient quantitative sensing of trace water content in DMF. The DL value ofPI-OSi·F for sensing water in DMF is determined to be 0.00149% (v/v). The solution color ofPI-OSi·F returns to colorless when the water content increases, indicating thatPI-OSi·F can conveniently estimate water content in DMF by naked-eye detection. The detection mechanisms confirmed by an1H NMR study and a DFT calculation involve a F−-induced desilylation reaction ofPI-OSito form phenolate anion followed by protonation with trace water. Finally,PI-OSifilm was fabricated for the colorimetric detection of F−and water in CH3CN.Keywords:tert-butyldiphenylsilyl-containing polyimide;colorimetric and ratiometric chemosensor;fluoride ions;trace water