Fluorescent Sensor for Sequentially Monitoring Zinc(II) and Cyanide Anion in Near-Perfect Aqueous Media

We report a new sensor, 1, for sequentially detecting Zn 2+ and CN – based on fluorescence. Sensor 1 was prepared through the reaction of 3-aminobenzofuran-2-carboxamide with 4-diethylaminosalicylaldehyde. Sensor 1 showed a selective “off–on” fluorescent response toward Zn 2+, distinguishing Zn 2+ from Cd 2+ . The limit of 1 (0.35 μM) for monitoring Zn 2+ is lower than the World Health Organization (WHO) guideline (76 μM) for water available for drinking. Importantly, sensor 1 could sense Zn 2+ in living cells and aqueous media. In addition, the resulting 1 –Zn 2+ complex functioned as an efficient “on–off” sensor for CN – . The mechanisms of 1 for detecting Zn 2+ and CN – were explained by spectroscopic, spectrometric, and theoretical studies.