A tetraphenylethylene-based aggregation-induced emission sensor: Ultrasensitive "turn-on" fluorescent sensing for phosphate anion in pure water.

A new fluorescent sensor of tetraphenylethylene (TPE) derivate with four dimethylformamidine and four chloride anions, sensor 1, was resoundingly synthesized. Meanwhile, the structure of sensor 1 has been characterized by H NMR, C NMR, FT-IR and mass spectrum. Sensor 1 can dissolve in water completely and showed significant fluorescence enhancement response towards PO with selectivity and sensitivity in pure water. The results of fluorescence spectra, turbidity measurement, dynamic light scattering (DLS) and fluorescent micrographs elucidated that the distinct fluorescence enhancement of sensor 1 with PO anion can be attributed to the aggregation-induced emission (AIE) of TPE. The AIE of sensor 1 with PO anion was reversible, proved by the alternate addition of PO anion and calcium ion. The fluorescence intensity of sensor 1 at 510 nm gradually increased and was obviously augmented by 266% when the added concentration of PO was 150 μmol L (15 equiv. of sensor 1). In addition, the fluorescence intensity also displayed a good linear relationship with PO ions in the large concentration range of 10-150 μmol L with very low detection limit for PO of 6.56 × 10 mol L. Furthermore, sensor 1 also presented the semi-quantitative visual detection ability for PO in solutions and test paper mode via the fluorescence changes and quantitative detection potential for PO in actual water sample.