Colorimetric probes designed to provide high sensitivity and single selectivity for CN− in aqueous solution

Abstract

The specific colorimetric detection of CN⁻ in the context of interference from coexisting anions, such as F⁻, AcO⁻, and H₂PO₄⁻, in aqueous solutions is still a challenge. Therefore, easily-made CN⁻ colorimetric probes L1–L4 bearing hydrazone moieties as the binding sites and nitrophenylfuran moieties as the signal groups were designed and synthesized. Probe L1 showed excellent colorimetric single selectivity and sensitivity for CN⁻ in DMSO/H₂O solution. When CN⁻ was added to the solution of L1, a dramatic color change from yellow to violet was observed, while the anions F⁻, Cl⁻, Br⁻, I⁻, AcO⁻, H₂PO₄⁻, HSO₄⁻ and ClO₄⁻ did not interfere with the recognition process for CN⁻. The detection limits of CN⁻ were 8 × 10⁻⁵ and 5 × 10⁻⁶ mol L⁻¹ according to the visual color changes and UV-vis changes, respectively.