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.

In this research, a novel 1,8–naphthalimide–based colorimetric and ratiometric fluorescence chemoprobe (NAPH) was realistically developed for the recognition of copper (II) (Cu²⁺) in different vegetables and drinkable water samples. The sensing studies of NAPH depicted a ratiometric ''turn–on'' fluorescent response from bright yellow to blue as well as a colorimetric response toward Cu²⁺ from yellow to colorless, and it was found to be unselective towards various metal ions, anions and amino acids. The fast response of NAPH to Cu²⁺ caused a wavelength shift from 550 nm to 454 nm, and hence NAPH was used to recognize Cu²⁺ with an ultralow detection limit (9.53 nM). To validate the spectral data of NAPH, the study was performed using important analytical parameters and statistical tests. The binding stoichiometry between NAPH and Cu²⁺ was computed as 1:1 by Job's plot method as well MALDI TOF MS. Besides, the binding constant between the NAPH and Cu²⁺ was found to be 6.84 × 10³ M–¹. In addition to sensing studies, density–functional theory (DFT) findings strongly confirmed spectral data, and the Smartphone sensing results demonstrated that NAPH could be utilized as a powerful tool for the monitoring of Cu²⁺ without the need for sophisticated equipment. A test paper application was also performed to achieve semi–quantitative detection and to produce test kits with excellent selectivity toward Cu²⁺ without interfering metal ions. Furthermore, the newly designed probe NAPH was not only successfully used to recognize Cu²⁺ in bottled drinking waters (93.93–103.97%) but also was employed for vegetables with satisfactory results (92.97–109.92%).