A water-soluble azobenzene-dicyano pendant polymeric chemosensor for the colorimetric detection of cyanide in 100% aqueous media and food samples

Abstract

Tracing toxic cyanide (CN⁻) in water and cyanogenic food samples is a demanding task for the research community. However, the poor solubility of organic probes in aqueous media often becomes a huge hurdle for in-field application. Herein, a novel colorimetric water-soluble polymeric probe, p(N,N′-dimethylacrylamide-co-azo-dicyano) (p(DMA-co-azo-dicyano)), P1, was created and synthesized for the purpose of detecting CN⁻ in 100% water. Specifically, P1 was synthesized via post-polymerization modification of (p(DMA-co-azo-aldehyde)) with malononitrile. P1 demonstrated selective sensing behaviour toward CN⁻ in water at physiological pH using intramolecular charge transfer (ICT) as a mechanism. Upon the inclusion of CN⁻, the color of P1 changed from red to yellow (a ∼57 nm blue shift) with the lower limit of detection (LOD) of 0.008 mM. Additionally, P1-coated test strips were used for “in-the-field” measurements for CN⁻ detection in aqueous solution and cyanogenic food samples.