Optical sensing of hydrogen sulphate using rhodamine 6G hydrazide from aqueous medium

Abstract

This communication reports the application of rhodamine 6G hydrazide (L) for the selective colorimetric and turn-on fluorescent sensing of hydrogen sulphate ions from aqueous medium. The ring opening of the colourless spirocyclic form of L was selectively triggered in the presence of HSO4− among the other tested anions (F−, Cl−, Br−, I−, AcO−, H2PO4−, NO3−, ClO4−, CN−, HO−, AsO33− and SO42−), which gives rise to a pink colour and strong fluorescence in the visible region. Sensor L showed a detection limit down to micromolar range without any interference from the other tested competitive anions. Sensor L was applied for the construction of two inputs (HO– and HSO4−) INHIBIT type molecular logic gate and naked-eye detection of HSO4− using test paper strips.