Pyrene-Functionalized Ruthenium Nanoparticles as Effective Chemosensors for Nitroaromatic Derivatives

Pyrene-functionalized Ru nanoparticles were synthesized by olefin metathesis reactions of carbene-stabilized Ru nanoparticles with 1-vinylpyrene and 1-allylpyrene (the resulting particles were denoted as Ru=VPy and Ru=APy, respectively) and examined as sensitive chemosensors for the detection of nitroaromatic compounds, such as 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 1-chloro-nitrobenzene (CNB), and nitrobenzene (NB), by their effective quenching of the nanoparticle fluorescence. It was found that the detection sensitivity increased with increasing nitration of the molecules. Additionally, in comparison to monomeric pyrene derivatives, both Ru=VPy and Ru=APy nanoparticles exhibited markedly enhanced performance in the detection of nitroaromatic explosives, most probably as a result of the enhanced collision frequency between the fluorophores and the quencher molecules. Furthermore, Ru=VPy nanoparticles displayed much higher sensitivity (down to the nanomolar regime for TNT) than Ru=APy in the detection of these nitroaromatic explosives, which was ascribed to the extended intraparticle conjugation that provided efficient pathways for energy/electron transfer and consequently amplified the analyte binding events.