Supramolecular Agent–Simulant Correlations for the Luminescence Based Detection of V-Series Chemical Warfare Agents with Trivalent Lanthanide Complexes

Solution spectroscopic investigations into the interactions of eight potential bidentate V-series organophosphorus chemical warfare agent (OP CWA) simulants with [Eu(phen)₂(NO₃)₃]·2H₂O demonstrated that the chemical and structural composition of the secondary binding site within the simulant was of paramount importance. Only simulants containing both phosphoryl/phosphonyl and amine moieties generated analogous spectroscopic behaviours to V-series OP CWAs seen in previous studies. The results demonstrated that the bidentate chelation mechanism was driven by the phosphoryl/phosphonyl moieties and that the presence of the amine moieties induced a significant secondary dynamic luminescence quenching mechanism. The binding modes of the simulants VO and TEEP to trivalent lanthanides (Eu and La) were further investigated using ¹H and ³¹P NMR spectroscopic titrations and kinetic IR experiments. VO, with both the phosphonyl and amine binding sites was found to be the most appropriate simulant for V-series OP CWAs in supramolecular studies with trivalent lanthanide ions and we recommend VO for use in supramolecular studies of this type. Solution spectroscopic investigations with potential bidentate V-series OP CWA simulants with [Eu(phen)₂(NO₃)₃]·2H₂O demonstrated the interaction and luminescence quenching mechanism to be specific and selective for bidentate systems containing both amine and phosphoryl/phosphonyl moieties. Only the low toxicity V-series simulant VO generated analogous spectroscopic behaviours to the OP CWAs VX and VG.