Fluorescence quenching of triarylamine functionalized phenanthroline-based probe for detection of picric acid

Abstract

Detection of toxic nitro aromatic compounds (NAC) using a cost-effective fluorescence sensing method have gained global attention. The current work demonstrates the selective sensing of picric acid using imidazo[4,5-f]-1,10-phenanthroline-triarylamines. The specific interaction mode of sensor molecules with NACs is established by absorption and emission spectroscopic methods. Remarkably, a new band appeared in the range of 420–480 nm. This new band increased the probability of overlap of the absorption with the emission spectra and ensures the FRET mechanism. The presence of electron rich methoxy group on TAA side arm improved the interaction with electron deficient picric acid with a binding constant of 1.46 × 105 M−1. The linearity of the Stern-Volmer plot confirms the mechanism is static quenching. The detection limit was calculated to be at micro molar level for all the four compounds. Density functional theory was employed to study the HOMO -LUMO of the compounds and informs that the energy transfer is more feasible from electron rich sensor molecule to picric acid. These molecules can act as efficient fluorescence sensor for selective picric acid detection.