Highly selective turn-on fluorogenic chemosensor for Zn(II) detection based on aggregation-induced emission

A simple and effective active aggregation-induced emission (AIE) fluorescent sensor, 1-(2-hydroxynaphthylmethylene)- 2-(2-hydroxybenzylidene) hydrazine, was synthesized via a simple reaction requiring inexpensive reagents. It displayed swift response, excellent selectivity, and speedy sensitivity toward Zn2+ based on its notable chelation enhanced fluorescence/AIE characterization. The sensor can detect Zn2+ by colorimetric and selective turn-on fluorescence responses. Furthermore, the formation of the sensor-Zn2+ complex with 1: 1 stoichiometry was confirmed by mass spectrometry. When the sensor bound with Zn2+, fluorescence-enhanced emission was observed via the chelation effect. Fluorescence intensity was considerably enhanced through aggregate formation when excessive Zn2+ was added. As the response time was similar to 5 s, the sensor was used to track Zn2+ at real time. The sensor could detect Zn2+ as low as 46 nM, and the recovery of urine samples with addition of Zn2+ ranged from 90.8% to 111.8%. The AIE mechanisms of the sensor and sensor-Zn2+ complex were explored by scanning electron microscopy, optical fluorescence microscope, and fluorescence reversibility study. In addition, the potential for practical applications was demonstrated through a simple and effective filterpaper- based method by exploiting the AIE mechanism.