A tetraphenylethylene-based aggregation-induced emission sensor: Ultrasensitive "turn-on" fluorescent sensing for...

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 ¹H NMR, ¹³C NMR, FT-IR and mass spectrum. Sensor 1 can dissolve in water completely and showed significant fluorescence enhancement response towards PO₄^3- 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 PO₄^3- anion can be attributed to the aggregation-induced emission (AIE) of TPE. The AIE of sensor 1 with PO₄^3- anion was reversible, proved by the alternate addition of PO₄^3- 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 PO₄^3- was 150 μmol L^-1 (15 equiv. of sensor 1). In addition, the fluorescence intensity also displayed a good linear relationship with PO₄^3- ions in the large concentration range of 10-150 μmol L^-1 with very low detection limit for PO₄^3- of 6.56 × 10^-8 mol L^-1. Furthermore, sensor 1 also presented the semi-quantitative visual detection ability for PO₄^3- in solutions and test paper mode via the fluorescence changes and quantitative detection potential for PO₄^3- in actual water sample.