A simple azoquinoline based highly selective colorimetric sensor for CN^- anion in aqueous media

Azoquinoline based sensor AZQ was designed and synthesized as a new molecular ion sensor containing an azo group in its structure. The structural characterization of AZQ was carried out using FTIR, NMR, mass, and elemental analysis. Then, the interaction of AZQ with anions was observed visually and UV-vis measurements were made in EtOH/H₂O (1:1, v/v) solvent mixture. As a result of this investigation, it was determined that AZQ is a fast and highly selective sensor for CN^- ions. The solution colour of AZQ changed from light yellow to orange only in the presence of CN^- ions. The limit of detection of AZQ was calculated as 2.6 μmol/L from anion titration experiments. Also, to identify the interaction mechanism of AZQ with CN^- ions, ¹H NMR spectra of AZQ in the presence of CN^- anions were recorded and the structure was proposed for AZQ-CN^- host-guest complex. (author)