Detection of HSO₄⁻ ion based on the hydrolysis of diketopyrrolopyrrole-derived Schiff base with chromogenic and fluorogenic dual signals.

A new diketopyrrolopyrrole-based Schiff base L was synthesized and its anion sensing behavior was explored. L showed exclusive response toward HSO4(-) ion and also distinguished HSO4(-) from other anions by color changes (from dark red to orange) and 21 fold fluorescence enhancement at 370 nm in aqueous solution (THF/H2O = 8/1, v/v). The sensing mechanism was suggested to proceed via a hydrolysis process. The results provided colorimetric and fluorimetric assays to selectively detect the presence of a HSO4(-) over a wide range of other interfering anions. The results could potentially be used as a dual colorimetric-fluorescent probe for monitoring HSO4(-) levels in physiological and environmental systems.