A pyrene-incorporated BODIPY-based colorimetric and fluorometric chemodosimeter for cyanide recognition and its bio-imaging application.

A pyrene-incorporated BODIPY-based sensor (L1) was prepared as an efficient colorimetric and fluorometric chemodosimeter for detecting the cyanide anion in acetonitrile/HEPES buffer (5 mM, pH 7.2, 1 : 9 v/v) at room temperature. The probe L1 exhibited a distinct visual color change and selectively showed a fluorogenic "turn-off" response to cyanide ions in acetonitrile/HEPES buffer. Mechanistic investigations indicated that nucleophilic addition of cyanide at the α-position of the dicyanovinyl moiety inhibited the intramolecular charge transfer of L1 and induced significant shifts in absorption and emission. Various techniques, including optical spectroscopy, NMR titration, HRMS analysis, and theoretical simulations, were used to investigate L1's sensing mechanism. The presence of competing anions had minimal or no impact on this cyanide identification process. The probe achieved an outstanding detection limit of 4.33 × 10-8 M. Furthermore, L1-impregnated filter paper strips enabled a visual, colorimetric, strip-based test that shifted from dark yellow to colorless upon exposure to cyanide. In addition, a smartphone-based technique was developed to capture the color shift, showing immense promise for cyanide detection without the need for sophisticated equipment. The formulation of L1 into an INHIBIT logic gate for facilitating cyanide identification using electronic devices is one of the significant applications. More significantly, L1 has been effectively used for fluorescence bioimaging in HeLa cells and for detecting cyanide anions in food samples, serving as an affordable and selective fluorescent sensor.