A turn-on fluorescent chemosensor (H-1) for cyanide anions based on dihydroxy phenazine was designed and synthesised. The sensor H-1 exhibits high sensitivity and good selectivity for cyanide in pure water. The CN− response mechanism involves a hydrogen bonding and deprotonation process in the sensor, which induced prominent fluorescence enhancement. The detection limit of the sensor toward CN− is 5.65×10−7M, and other anions had nearly no influence on the probing behavior. In addition, test strips based on the sensor were fabricated, which also exhibit a good selectivity to CN− in water. Notably, this sensor was successfully applied to detect CN− in food samples, which proves a very simple and selective platform for on-site monitoring of CN− in agriculture samples.

The identification of CN– in water, seeds, and biological systems has, because of its high toxicity, attracted the increasing attention of many chemical industry researchers. In the work, a novel highly selective and reversible sensor, MMY, was shown to recognize CN– effectively. The color and fluorescent changes verified the interaction of MMY with CN–, and the fluorescence lifetime of MMY was also changed upon addition of CN–. A mode of interaction of MMY with CN– based on the results of various experiments was speculated. The LOD of MMY toward CN– was 9.4 × 10–¹⁰ M, lower than the concentration of CN– deemed acceptable by the WHO (World Health Organization) and the U.S. EPA (United States Environmental Protection Agency). MMY showed good reversibility and reusability for detecting CN–. In addition, test slips and silica plates were both earned by ourselves, which were able to recognize CN– qualitatively. Additionally, MMY could recognize CN– in tap water quantitatively with the use of a smartphone APP. Interestingly, MMY was also used to detect CN– in seeds. It was valid to image CN– in Caenorhabditis elegans and mice with a vivid “turn-on” fluorescence. MMY thus can circulate in the bloodstream.

Development of colorimetric sensors has emerged as an attractive strategy for cyanide detection owing to their unique advantages, including simple visual detection and economical nature. In this work, anthraquinone derivatives (3a-d) have been easily prepared via nucleophilic substitution of 1-chloro anthraquinone with substituted phenylacetonitriles, with only nitro-substituted anthraquinone 3d displaying colorimetric sensor capabilities. The sensor showed good selectivity, reversibility and reusability toward cyanide detection, as well as efficient naked-eye color change from colorless to blue-purple in a neutral aqueous medium. The deprotonation mechanism of CH was investigated by NMR spectroscopy and supported by DFT calculations. Furthermore, the sensor 3d was successfully loaded onto test strips as a convenient and efficient solid-state sensor for cyanide detection. It was utilized for cyanide detection in cassava flour and bitter almonds food samples, as well as displaying excellent performance in real-world water samples.

Although hydrosulfide and cyanide anions play important roles in daily life that they are available in a lot of foods. However, their excess amounts contaminate water, land, and food and cause serious problems to human health. Herein, we introduce a water-soluble macrocyclic sensor based-on Calix[4]arene (MPI-Calix[4]) with dual response sites for fluorescence recognizing cyanide (CN–) and hydrogen sulfide (HS⁻) under longwave light. MPI-Calix[4] exhibits a high selectivity and sensitivity in the detection of CN– and HS⁻, where the limits of detection were as low as 0.115 and 8.12 μmol/L, respectively. The cell imaging studies shows that this probe can be easily used in the detection of CN– and HS⁻ on living cells. Full understanding of these results paved a fruitful system to improve an applicable analytical process for food safety and quality.