Bis-pyrene carbocations for chromogenic and fluorogenic dual-detection of fluoride anion in situ

We have designed and synthesized a new carbocation precursor (carbinol) based on bis-pyrene derivative. The carbinol can be transformed to stable carbocations with quenched fluorescence and long wavelength absorption. The stable carbocations can be further used as fluoride anion detection in acidic environment, which show both chromogenic and fluorogenic responses in the presence of fluoride anion. UV–vis and fluorescence spectroscopy were utilized to monitor the changes during detection process. The responsive mechanism was studied by quantum chemical calculations and the results indicate that the carbocation mediated formation of C–F covalent bond leads to this dual responsive phenomenon. The bis-pyrene carbocations and corresponding F adduct was confirmed MALDI-TOF mass spectrum. The successful elucidation of this new mechanism opens a new avenue for carbocation-based sensor or biological labeling in the future.