Effective strategies for the detection and identification of explosives are highly desirable. Herein, we illustrate the efficient optoelectronic detection of nitroaromatic and peroxide-based explosives using amine- and phosphine-substituted diketopyrrolopyrroles. Selective quenching and an unprecedented enhancement of thin-film emission in the presence of nitroaromatic vapors are demonstrated via the judicious choice of amine substituents. The modulation of fluorescence emission in each case is shown to be dominated by electronic and thermodynamic effects, the vapor pressure of explosives, and the thin-film morphology. For peroxide detection, we describe an approach exploiting redox-mediated functional group transformation. The rapid oxidation of triphenylphosphine to phosphine oxide with hydrogen peroxide affords a significant increase in fluorescence emission, facilitating the sensitive turn-on detection of an important class of explosives at ppb concentrations.
Keywords: diketopyrrolopyrroles; explosives; fluorescence detection; nitroaromatics; peroxides; thin films.