Fluorescent Detection of 2,4‐DNT and 2,4,6‐TNT in Aqueous Media by Using Simple Water‐Soluble Pyrene Derivatives

Abstract

Pyrene-containing water-soluble probes for the fluorescent detection of nitroaromatic compounds (NACs), such as explosive components (2,4-DNT and 2,4,6-TNT) and herbicides (2,4-dinitrocresol, 2,4-DNOC), in aqueous media are reported. In the probes, the introduction of surface-active hydrophilic "heads" at the periphery of lipophilic (i.e., hydrophobic) pyrene "tails" resulted in the formation of highly fluorescent micelle-like aggregates/pre-associates in aqueous solutions at concentrations of ≤10(-5) m. The enhanced fluorescence quenching of the herein reported architectures is achieved in the presence of ultra-trace amounts of TNT or 2,4-DNT with values of Stern-Volmer quenching constant close to 1×10(5) m(-1) and a detection limit as low as 182 ppb. The most hydrophilic probes demonstrated higher response to 2,4-DNT over TNT. Filter paper test strips impregnated with 1×10(-5) m solutions of the probes were able to detect TNT, 2,4-DNT, and other NACs at levels as low as 50 ppb in water.

Computer vision vs. spectrofluorometer-assisted detection of common nitro-explosive components with bola-type PAH-based chemosensors

“…In an aqueous organic or polar environment, these bolas-type molecules could act as non-ionic surfactants, which would exhibit an enhanced excimer emission due to the bending of the molecules 1-2 over the pentane linker and the following proximity effect between two PAH molecules, while the monomeric emission of 1-2 would be suppressed. We observed similar effects in cyclic cyclophanes (pillar [6]arenes) in polar solvents media, 50 in recently reported micellar pyrenebased chemosensors for explosives 51,52 as well as in chemosensors for anions. 53 In the micellar chemosensors the local non-polar "friendly" environment inside the body of micelle was the driving force for the less polar molecules, for instance, nitro-aromatic explosives (NAE), to transport from the polar solvent media inside the non-polar cavity of the micellar chemosensor.…”

“…Hence, we could conclude the following: from one side, we did not observe the decomposition of micelles/micelle-like particles of compounds 1-2 by DNT, and on the other side in DMSO : H 2 O [1 : 1 (v/v)] solution these stable particles were involved in interactions with nitro-aromatic quenchers (NAQ) to result in the dramatic uorescence quenching which as it was reported earlier for other types of micellar chemosensors. 51,52 The features of the excimer and its quenching by NAE in a nonpolar medium were described above. In the aqueous environment, the Van der Waals' interactions between "hostile" dipoles of the solvent force the non-polar molecules of 1-2 to bend over the alkane linker in order to keep some non-polar "friendly" environment inside the sensor cavity.…”

Computer Vision-Based Portable System for Nitroaromatics Discrimination

“…A very good resolution, in the order of g/L, is achieved in every case, as well as very low LOD. The detection limits obtained are in the expected range for optical sensors, including colorimetric sensors [24,35] or fluorescence quenching based sensors [36][37][38]. Although other techniques for nitroaromatics sensing provide better LODs below 10 ppb, such as surface plasmon resonance [39] or mass spectrometry [40], they require very complex instrumentation that makes the development of simple and portable systems based on them nonviable.…”

Fluorescent Paper Strips for Highly Sensitive and Selective Detection of Nitroaromatic Analytes in Water Samples

“…For this purpose several new techniques such as fluorescence and colorimetric‐based systems have been developed for detection of NACs . Especially, among these developed systems, paper‐based systems have promising potential to fabricate desired portable and disposable sensor platforms . Taudte et al.…”