Detection of nitroaromatic explosives by new D–π–A sensing fluorophores on the basis of the pyrimidine scaffold

A series of D–π–A- type dyes based on pyrimidines, bearing various thiophene linkers, have been studied as sensing fluorophores. Fluorescence studies have demonstrated that the emission of all derivatives is sensitive to the presence of nitroaromatic explosives, such as 2,4,6-trinitrophenol (PA), 2,4,6-trinitrotoluene (TNT), and 2,4-dinitrotoluene (DNT), in their acetonitrile solutions. The detection limits of fluorophores to PA, TNT, and DNT proved to be in the range from 5.83 × 10−6 to 2.38 × 10−7 mol/L, 1.70 × 10−4 to 8.40 × 10−6 mol/L, and 8.39 × 10−5 to 6.87 × 10−6 mol/L, respectively. The theoretical investigation into the quenching mechanism in the presence of fluorophore has been performed. All compounds have shown a good efficiency as sensor materials when tested as elements of the original device «Nitroscan» for detecting nitro-containing explosives in vapor phase (Plant "Promautomatika", Ekaterinburg, Russia).