A simple pyrimidine based colorimetric and fluorescent chemosensor for sequential detection of copper (II) and cyanide ions and its application in real samples

Abstract

In this study, a new pyrimidine-based chemosensor (PyrCS) has been developed for sequential detection of copper (II) and cyanide ions. The PyrCS has revealed high sensitivity and selectivity toward copper ion over other metal ions in aqueous media. The PyrCS as an optical probe exhibited a distinct color change and a bathochromic shift in UV spectra in the presence of copper ion in a few seconds due to the formation of stable complex (PyrCS-Cu²⁺). The results confirmed that the PyrCS has a widely linear detection range of 0.3-30 μM toward Cu²⁺. The calculated limit of detection for Cu²⁺ ions was low as 0.116 μM. Moreover, the fluorescent intensity of PyrCS at 507 nm was significantly quenched in the presence of Cu²⁺ and Fe²⁺ ions. Additionally, complex PyrCS-Cu²⁺ was successfully used to detect cyanide ions via Cu²⁺ displacement approach. The free PyrCS was recovered after adding the CN‾ ions in a few seconds due to the formation of the stable copper cyanide complex Cu(CN)_x. The calculated LOD for CN‾ ions was low as 0.320 μM. The data also clarified that the other competing anions did not create a clear color change in solutions. Since the proposed method could provide a vivid colorimetric response in the presence of detected analytes within the pH range of 3-9, we can claim that the developed chemosensor can be utilized in any physical and biological conditions.

Keywords: 2,4,6-Triaminopyrimidine; Azo dye; Chemical sensor; Copper ion; Cyanide ion.