Development of efficient fluorescent sensor for the detection of hazard aromatic nitro compounds via N-(1-naphthyl)ethylenediamine: Experimental and DFT studies

Abstract

Selective detection of the poisonous aromatic nitro compounds (ANCs) in the industrial wastewater is urgently needed to regulate its percentage and thereby aid in environmental protection. The present study describes the application of N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA.2HCl) as a safe and effective fluorescence sensor for the detection of some hazard ANCs including 2,4-dinitrophenol (DNP), O-nitroaniline (ONA), 4-Chloro-2-Nitroaniline (CNA), P-Nitrobenzaldehyde (PNB), O-Nitrobenzaldehyde (ONB). The optical properties of NEDA.2HCl was investigated using both UV–vis and fluorescence spectroscopy at different pH and solvents. Luminescent properties exhibit that NEDA.2HCl has an emission peak at 429.2 nm when it is excited with a wavelength 326.4 nm. The Stern-Volmer equation appears that there is a good relation between the concentration of ANCs under investigation and the fluorescence intensity of NEDA.2HCl with high quenching rates ranging from 8.39 × 103 to 2.74 × 105 mol−1.L. Moreover, the coordination number of the binding sites (n) and the obtained binding constant (Ka) between NEDA.2HCl and ANCs were determined using the modified Stern-Volmer equation to study the behavior of both Ka and n with the variation of the quenching temperature. DFT calculations offered a thorough justification for the discovered quenching activity of the investigated quenchers and the quenching mechanism is proposed to occur through the electron transfer from HOMO of NEDA.2HCl into LUMO of ANCs. This technique offers a quick means to detect and thus reduce the number of hazardous ANCs in the environment, which will be of great benefit to both people and animals.