A novel colorimetric HSO4− sensor in aqueous media

A novel and sensitive anion receptor 3, bearing Schiff base structure, nitrophenyl azobenzol and carboxyl groups, was developed and characterized as a single chemosensor for the recognition of HSO4− anion. The different responses of UV–vis spectra and color changes of 3 could be applied to the recognition for HSO4− over other anions such as F−, CI−, Br−, I−, AcO−, H2PO4− and CIO4− by the naked eye. Furthermore, the anion binding interaction of receptor-anion was also studied using UV–vis and 1H NMR titration which revealed that 3 displayed a remarkable binding ability for the HSO4− with an association constant Ka = 6.59 × 104 M−1. And the detection limitation of HSO4− with the receptor 3 was 2.0 × 10−6 mol L−1 in aqueous solution. Most importantly, the qualitative detection of HSO4− using receptor 3 was attempted with test kit which was made from receptor 3.

A novel colorimetric sensor 3 was synthesized and exhibited single selectivity by naked-eyes on recognition for HSO4− in aqueous solution. The test strips were fabricated, which also shows a high sensitivity to HSO4−.Figure optionsDownload as PowerPoint slideHighlights
► A novel sensor 3 which we synthesized was never reported.
► The receptor is an excellent sensor in the recognition of HSO4− (very few reported).
► The recognition was carried out in aqueous system.
► The qualitative detection of HSO4− using sensor 3 test strips was attempted.