Sensing of organophosphorus pesticides by fluorescent complexes based on purine-hydrazone receptor and copper (II) and its application in living-cells imaging.

In this study, we used purine hydrazone derivatives and coumarin aldehyde to synthesize a novel fluorescent sensor (EDTP) by Schiff base reaction, which exhibited significant selective fluorescence quenching of Cu, and a distinct change from brilliant yellow to red is present along with the solution color. The detection limit of EDTP for Cu was 109.52 nM. Job's plot experiment, density flooding theory (DFT) and H NMR titration experiments revealed the possible binding mechanism of EDTP to Cu, the probe EDTP could achieve highly detection of Cu through forming a 1:1 complex. Additionally, this new fluorescent sensor EDTP-Cu can be further applied in the rapid and selective detection of pesticide residues in solutions. When the EDTP-Cu system was subsequently exposed to organophosphorus pesticides (glyphosate and glufosinate-ammonium), it was observed that the fluorescence was recovered and accompanied by a red to yellow color change. This may be attributed to the strong chelation of glyphosate and glufosinate-ammonium with Cu, leading to the dissociation of the EDTP-Cu system and thus triggering the fluorescence recovery effect. The detection limits of the EDTP-Cu system is 2.48 nM for glyphosate and 17.23 nM for glufosinate-ammonium, respectively. Finally, the developed sensor system has been successfully utilized image glyphosate and glufosinate-ammonium fluorescence in living cells. Purine fluorescence probes are a potential fluorescent probe for the detection of metal ions and pesticides due to their good characteristics. This study opens up a new way for the detection of fluorescent probes in pesticides.