Chromogenic and Fluorogenic Detection of Diethyl Chlorophosphate with Dansyl-Functionalized Copper(II) Complexes

The extremely poisonous nature of organophosphate nerve agents (OPNAs) leads to severe neurological damage and fatalities. Given their toxicity, there is an ongoing need to create efficient techniques for the detection of these substances. In this study, we explore the use of copper complexes functionalized with dansylamide ligands as potential probes for the detection of diethyl chlorophosphate (DCP), a G-series nerve-agent simulant. The sensitivity of the complexes to detect this simulant was evaluated by using fluorescence spectroscopy, yielding an optical detection limit as low as 40 nM and a visual detection limit of 1.2 mM. Tests with potential interferents showed no identical visual color change with that of DCP. The presence of water played an important role in detection sensitivity, and time-dependent density functional theory (TD-DFT) studies provided insights into the differences in reactivity among the tested complexes. Among the three complexes examined, copper(II)-dansyl-ethylenediamine [Cu(Ds-EN)2] gave the best response. This work highlights the synergistic fluorogenic properties of the dansylamide ligand and the chromogenic behavior of the Cu complex, offering a potential platform for the OPNA detection.