A novel barbituric-based fluorescent probe with aggregation induced emission for the highly sensitive ratiometric detection of cyanide anions

A new tetraphenylethylene-based barbituric acid derivative (TPEB) with an aggregation induced emission effect is synthesized as a fluorescent probe for CN − . The fluorescence spectra of TPEB in a DMSO–H 2 O mixture changed with different water fractions ( f w ). Nano-aggregates of TPEB are formed with the strongest fluorescence emission when f w beyond 60%. TPEB displays high selectivity and anti-interference toward CN − in DMSO–H 2 O ( f w 70%) system at pH around 6, even in the presence of other competitive anions (AcO − , F − , Cl − , Br − , I − , NO 3 − , SO 4 2− , ClO 4 − , PO 4 3− , SCN − , HS − , S 2− and H 2 O 2 ). The linear curve is excellently matched between the fluorescence intensity and CN − concentration at 500 nm. By the equation 3σ/S, the limit of detection of TPEB for CN − reaches 0.767 × 10 –6 mol L −1 . The probe TPEB operates via intramolecular charge transfer mechanism, attributed to the unique nucleophilic addition reactions between TPEB and CN − , which is further confirmed by LC–MS spectra, Job's plot and DFT calculations. By colorimetry and fluorescence approach, CN − ions can be easily detected by the TPEB testing strip. The probe can be used to distinguish the acidity and basicity of the solution qualitatively. Graphic abstract