Design and optimization of encapsulated sensor materials with diverse binding sites for efficient cyanide ion detection

Abstract

Developing colorimetric and fluorimetric sensors with a new design strategy incorporates the same electron donor and acceptor units by changing the binding site by expecting different mechanisms. The sensors YS and RS have the D-π-A concept, having phenothiazine as an electron donor and benzothiazole as an electron acceptor for sensing cyanide ions in various spectral techniques. Both the sensors showed an efficient color change with cyanide ion in day light and UV light, which was confirmed by UV–vis and Fluorescence spectral analysis. The mechanism of sensing cyanide ion by the sensor YS via hydrogen bond formation followed by deprotonation and RS via nucleophilic addition reaction was confirmed with a ¹H NMR, FT-IR and HRMS spectral studies. The detection limit was found to be 1.36 μM and 0.78 μM by UV–vis, 0.13 nM and 0.39 nM by fluorescence technique are for sensors YS and RS, which are significantly lower than the WHO criterion of 1.9 μM for cyanide ions in water used for drinking. Furthermore, the real-world application showed that the sensors could quantitatively identify the quantity of cyanide ion present in different types of water samples. Besides, the fabricated test strips make the sensors easy to utilize for detecting CN⁻ in the field without the need for complicated devices. Also, the developed sensor-encapsulated Polysulfone (PSF) capsule kit effectively senses cyanide ion in water.