Novel thiophene-based colorimetric and fluorescent turn-on sensor for highly sensitive and selective simultaneous detection of Al and Zn in water and food samples and its application in bioimaging.

A novel bifunctional thiophene-based Schiff base TS as a colorimetric and fluorescent turn-on sensor for rapid and simultaneous detection of Al and Zn ions with high selectivity and sensitivity has been developed. The sensor shows remarkable fluorescence enhancement response for Al and Zn over a broad pH range with good anti-interference capability, which accompanied with an obvious color change easily detected by naked eyes. Sensor TS can detect as low as 3.7 × 10 M for Al and 3.0 × 10 M for Zn, whereas respective association constants are 1.16 × 10 M and 2.08 × 10 M. With the help of fluorescence titration and Job's plot, the stoichiometric ratio of TS with Al/Zn was determined to be 1:1. The sensing mechanism of sensor TS with Al/Zn based on the chelation-enhanced fluorescence (CHEF) was analyzed in detail through H NMR titration, FTIR, HRMS and DFT studies. Moreover, sensor TS has been applied to the detection of Al and Zn in real environmental water and food samples as well as the filter paper-based test strips. Furthermore, sensor TS has good cell-permeability and can be used to selectively sense intracellular Al and Zn by bioimaging.