Detection of cyanide by a novel probe with a V-shaped structure based on aggregation of the probe adduct

Abstract

2-[2-[4-(Dimethylamino)phenyl]phenylethenyl]-1,3,3-trimethyl-3H-indolium iodide, a turn-on fluorescent probe for detection of the cyanide anion in aqueous solution with a novel V-shaped structure, is synthesized and characterized. Due to the considerably localized HOMO and LUMO on different “arms” of the probe, its fluorescence is completely quenched in aqueous solution caused by a strong ICT effect and intramolecular rotation of dimethylaminophenyl. However, the emission is dramatically intensified over 500 times when the probe is exposed to cyanide anions and the turn-on fluorescence should be ascribed to the aggregation of the probe adduct in aqueous solution. The probe, which displays a high selectivity and sensitivity for CN⁻ against other analytes, can finish the response within 20 s and the detection limit is measured to be as low as 55 nM. These merits make our cyanide probe one of the most effective ones ever reported.