Fluorescence Quenching as a Detection Method for Trace Explosives Using Perylene Diimide Derivatives in Solution and Organogels

Abstract. The detection of energetic materials at trace levels remains a critical challenge for both civilian and military security, especially in the context of increasing terrorist threats. Conventional detection techniques often lack universality and sensitivity, making it necessary to develop innovative approaches capable of identifying a wide range of explosives at very low concentrations. Optical spectroscopic methods, due to their non-destructive nature, cost-effectiveness, and adaptability to diverse chemical structures, represent a promising alternative. This research explores the potential of fluorescence-based techniques, specifically fluorescence quenching, as a sensitive and selective method for explosive detection. The study investigates the use of perylene diimide (PDI) derivatives as fluorophores for detecting nitroaromatic explosives through fluorescence quenching mechanisms. Experimental work involved preparing PDI solutions in dimethylformamide (DMF), N-methylpyrolidone and in organogel structures, determining optimal excitation wavelengths, and constructing calibration curves using a Jasco FP-6500 spectrofluorimeter. Subsequent tests assessed the quenching efficiency for several compounds, including TNT, diazodinitrophenol (DDNP), and sodium picramate. The quenching process was analyzed in terms of spectral overlap and energy transfer mechanisms, such as Förster resonance energy transfer (FRET), to explain the observed detection limits. Results demonstrated that the proposed method achieves detection limits in the ppm range for key nitroaromatic explosives, with TNT and DDNP showing limits of 6.5 ppm and 66 ppm, respectively, and sodium picramate exhibiting an exceptional limit of 2 ppm. These findings confirm the feasibility of fluorescence quenching as a highly sensitive technique for trace detection of explosives. The study opens new perspectives for developing portable, rapid, and cost-effective detection systems based on tailored PDI derivatives, contributing significantly to security and defense applications.