Naphthalene Flanked Diketopyrrolopyrrole: A New Functional Dye Based Optical Sensors for Monitoring Cyanide Ions in Water

Cyanide (CN-) is one of the most hazardous ions to humans and the environment. Therefore, sensitive, and selective sensors for CN- monitoring are highly required. A novel chemosensor based on naphthalene flanked diketopyrrolopyrrole dye (TBC-DPPN) is synthesized for the direct detection of CN- in water samples by naked eye and vibrational spectroscopy (UV-Vis and fluorescence). The electron deficient carbonyl group of the lactam ring of TBC-DPPN undergoes a nucleophilic attack by the CN- thus causing the yellow color of the dye turn to colorless, and fluorescence of the dye at 527 nm to turn-off. The mechanism of CN- sensing by the TBC-DPPN sensor is confirmed by spectral measurements and density functional theory (DFT) calculations. The TBC-DPPN sensor is utilized to determine the CN- by colorimetric and fluorescence methods in water down to 0.5 and 0.05 mu m, respectively, which is well below the cut off limit of 1.9 mu m that is recommended by the World Health Organization (WHO). Therefore, TBC-DPPN can act as dual channel sensor with high selectivity and sensitivity for the determination of CN- in water.

Automated summary

Cyanide is a hazardous ion, and there is a high demand for sensitive and selective sensors for its monitoring. The novel chemosensor TBC-DPPN can detect CN- in water samples through visual and vibrational spectroscopy, with high selectivity and sensitivity. The mechanism of CN- sensing by TBC-DPPN sensor is confirmed by spectral measurements and DFT calculations, enabling detection of CN- in water below recommended limits.