A novel azo-triazolopyridine-based dual naked-eye chemosensor for the selective detection of CN− and Cu2+ ions

Abstract

A new chemosensor incorporating a triazolopyridine and an azo chromophore was synthesized and employed as a colorimetric sensor. Visual investigations for detecting anions and cations revealed that the sensor acts as a highly sensitive and selective chromogenic detector for cyanide (CN⁻) and copper (Cu²⁺) ions. The observable color change from yellow to deep orange for Cu²⁺ and from yellow to purple for CN⁻ allows for detecting these ions without the need for advanced equipment, even with the naked eye. The sensor’s limit of detection (LOD) was determined to be 0.02 μM for CN⁻ ions and 1.13 μM for Cu²⁺ ions. The Job plot indicated that the sensor binds to CN⁻ and Cu²⁺ with a stoichiometric ratio of 1:1 and 2:1, respectively. The ability to accurately and selectively distinguish Cu²⁺ and CN⁻ ions makes this sensor valuable for various analytical applications, including environmental monitoring and chemical analysis. Its capacity to produce noticeable and distinct color changes enables the rapid and straightforward detection of these hazardous ions, making it a practical choice for real-world applications. The quantum yield of A-TAP/Cu²⁺ was 54 % at a λ_max (maximum absorbance) of 450 nm, while that of A-TAP/CN⁻ was 62 % at 538 nm, using a reference sensor with a λ_max of 380 nm.