An indanedione-based chemodosimeter for selective naked-eye and fluorogenic detection of cyanide

Abstract

A 1,3-indanedione-based chemodosimeter 1 with both intramolecular charge transfer (ICT) and aggregation-induced emission enhancement (AIEE) characteristics has been developed for the highly selective and sensitive detection of cyanide (CN−) in a 90% aqueous solution. The colorimetric and ratiometric fluorescent response of the chemodosimeter to CN− is attributable to the addition of CN− in the β-conjugated position of the 1,3-indanedione moiety of chemodosimeter 1, which blocks ICT. The hypothesized sensing mechanism is supported by time-dependent density functional theory (DFT) calculations. Chemodosimeter 1 achieves rapid detection of CN− in anhydrous THF (a response time less than 1min), and only 2 equivalents of CN− is required to reach the spectral saturation. The effect of water on the reaction of the chemodosimeter to CN− is also examined. The results show that increasing water content results in a longer reaction time due to the solvation of CN− by neighboring water molecules. Chemodosimeter 1 also exhibits excellent fluorescence responses in the solid state, and 1-based test strips can be used to conveniently detect CN− by the naked eye. The detection limit of chemodosimeter 1 (9.4×10−7M) for CN− is two times lower than the maximum permissible level of CN− (1.9×10−6M) in drinking water.