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 2+ , and a distinct change from brilliant yellow to red is present along with the solution color. The detection limit of EDTP for Cu 2+ was 109.52 nM. Job's plot experiment, density flooding theory (DFT) and 1 H NMR titration experiments revealed the possible binding mechanism of EDTP to Cu 2+ , the probe EDTP could achieve highly detection of Cu 2+ through forming a 1:1 complex. Additionally, this new fluorescent sensor EDTP -Cu 2+ can be further applied in the rapid and selective detection of pesticide residues in solutions. When the EDTP -Cu 2+ 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 2+ , leading to the dissociation of the EDTP -Cu 2+ system and thus triggering the fluorescence recovery effect. The detection limits of the EDTP -Cu 2+ 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.