Aryl Ethynylpyrene as Fluorescent Sensors for Cyanide Ions in Aqueous Media

Three derivatives of aryl ethynylpyrene are successfully synthesized via a Sonogashira coupling‐Knoevenagel condensation sequence. Two of these compounds exhibit excellent selective fluorescent enhancement by CN − in aqueous media with detection limits of 0.066 and 0.087 μM. The 1 H‐NMR analysis suggests that the sensing mechanism involves a nucleophilic addition of CN − to the reactive olefinic group. In the solution phase, these sensors can be used for the determination of spiked CN − in real water samples at 5 and 10 μM with relative standard deviation of below 4 %. When fabricated into paper‐based sensors, they can be used to detect CN − in aqueous media at the micromolar levels by naked eyes.