Colorimetric recognition of acetate anions in aqueous solution using charge neutral azo derivatives

Two novel highly sensitive colorimetric acetate anion receptors: 4-phenylazo-2-hydroxy-benzaldehyde 4-nitrophenylhydrazone (1) and 4-phenylazo-2-hydroxy-benzaldehyde 2,4-dinitrophenylhydrazone (2) based on azo derivative have been designed and synthesized. UV–vis experiments show that receptor 1 and receptor 2 can selectively recognize acetate in DMSO and even in 9/1 DMSO/H2O (v/v) mixtures. Meanwhile the color changes induced by anions can provide a way of detection by ‘naked-eye’. The further insights to the nature of interactions between receptor 1, 2 and AcO− have been investigated by 1H NMR titration experiments.

Figure optionsDownload as PowerPoint slideHighlights
► The synthesis process of the two receptors is simple and easy. Thus, it made them in practical use possible.
► The color changes induced by anions can provide a way of detection by ‘naked-eye’. Receptor 1 and 2 recognizing acetate could occur not only in DMSO solution, but also in DMSO/H2O (9:1, v/v) solution.
► Receptors 1 and 2 can recognize acetate is of great importance, because acetate is an important biological molecule.