Selective fluoride ion sensing using novel quinoline chemosensor insights into kinetics and molecular logic gate...

CQHC, a novel colorimetric fluorescent sensor, developed for the selective sensing of ions and well characterised, including SC-XRD. It demonstrated selective sensing for Co²⁺, Zn²⁺, Hg²⁺ and F^- using absorbance titration at 420 nm, 446 nm and the binding constants estimated follows the order F^- > Co²⁺ > Hg²⁺ > Zn²⁺. On light of this, molecular logic gate was built for CQHC's selective multi-ion detection. However, fluorescence titration analysis revealed that CQHC is solely selective for F^- ions. This conclusion was validated by ¹H-NMR titration, clearly showed deprotonation occurs from N₃-H. Fluorescent decay titration, kinetic investigations and computational studies all contributed to the selective sensing of F^-. According to TD-DFT calculations, added fluoride ion interacts with N₃-H proton and deprotonates to generate F-H in the excited state.