A multi-branched triphenylamine Schiff base derivative for picric acid turn-on detection

Developing fluorescence probes with a turn-on model for picric acid (PA) detection is a challenge due to its fluorescence quenching property. In this work, a novel multi-branched triphenylamine Schiff base derivative (TPAS) was designed, synthesized, and characterized. TPAS performed well in PA detection, exhibiting weak emission in organic solvents and aqueous environments. However, bright fluorescence was observed in the aqueous solution of TPAS after adding PA. Moreover, the response of TPAS to PA was not affected by the other nitroaromatic compounds and had a limit of detection of 43 nM, which was lower than most of the reported PA probes. According to the mechanism study, the increased fluorescence was caused by the PA-induced hydrolysis of the Schiff base to the highly emissive amino precursor. This work provides new insights into designing novel PA probes with a turn-on model.

Graphical abstract

A novel multi-branched triphenylamine Schiff base derivative (TPAS) was used for picric acid turn-on sensing with a lower limit of detection by inducing the hydrolysis of the Schiff base to the highly emissive amino precursor.