Synthesis of novel colorimetric probe molecules and their application in anion recognition based on strong hydrogen bond

A novel pair of ferrocene-containing azobenzene-based probe molecules, which behave as a selective probe for sensing fluoride and dihydrogen phosphate in colorimetric systems (even by naked eye), were designed. The probe 2 (N,N′-bisamideazophenyl-ferrocene) showed a high selectivity toward F− and H2PO4−H2PO4− with a color change from yellow to salmon pink without any interference from other ions. Meanwhile, the probe 1 (4-amideferrocenylazobenzene) showed only high selectivity for F− with a color change from yellow to salmon pink without any interference from other ions.

Graphical abstractIt is the first time naked-eye detection of fluoride and dihydrogen phosphate ions around the guideline value from Guidelines of World Health Organization for Drinking-Water Quality. Compared one and two combining (sensing) groups would induce the different interaction, which will lead to the different color change. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A couple of ion-probes were synthesized and characterized. ► The first time for naked-eye detecting both fluoride and dihydrogen phosphate. ► Ferrocenyl group would draw into rotation isomerisation for ions recognition.