Intermolecular π-π interactions-induced aggregation based on bispyrene for ultrasensitive detection of picric acid (PA) and 2,4-dinitrophenol (DNP)

Abstract

It was still important to explore excimer emission-based fluorescence probes for nitroaromatics detection by formation or destruction of pyrene excimer with strong emission change. In this work, we have synthesized a simple bis(pyrene) derivative (BisPyH) and studied its optical behavior by using UV–vis and fluorescent spectroscopy. In pure DMSO solution, it emitted a weak blue fluorescence due to the formation of excimer states, on the contrary, the BisPyH in the DMSO/H2O (v/v, 1:1) mixture solution was self-assembled to form aggregates via intermolecular π-π interactions among pyrene units, giving almost 10-fold fluorescence enhancement compared to that in pure DMSO solution. The formed aggregates just offered a perfect platform for the selective detection PA and DNP explosives by quenching the bright green intermolecular-excimer emission in competitive environment. BisPyH exhibited a limit of detection (LOD) towards PA, and DNP as low as 7.32 × 10−8, and 8.11 × 10−8 M, respectively. Subsequently, the fluorescence quenching mechanism was demonstrated by the density functional theory (DFT), UV–vis and fluorescence spectra, SEM, and the quenching constants. Furthermore, filter paper strips and thin-layer chromatography (TLC) plates coated with BisPyH were able to detect PA and DNP in the practical application.