Detection of 2,4,6-trinitrophenol based on f–f transition of Eu2

• Published in: Journal of rare earths 2021-08, Vol.39 (8), p.952-958
• Main Authors: Zhang, Xuan, Liu, Litao, Zhang, Wei, Na, Liyan, Hua, Ruinian
• Format: Article
• Language: English
• Subjects: BaAlF5:Eu2; BaSiF6:Eu2; f–f transition of Eu2; LRET; Rare earths; TNP
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/j.jre.2020.06.016

In this paper, we designed Eu2+-doped BaAlF5 and BaSiF6 downconversion nanophosphors with strong f–f transition emission to realize the quantitative detection of TNP. The surface of the as-prepared nanophosphors was modified by polyethylenimine (PEI) to increase the water solubility and to provide a pair of electrons to bind to the benzene ring in TNP, forming a Meisenheimer complex. The detection principle of TNP is based on luminescence resonance energy transfer (LRET) technology, where the PEI-functionalized BaAlF5:Eu2+ and BaSiF6:Eu2+ nanophosphors are used as energy donors and TNP is an energy acceptor. With increasing TNP concentrations, the luminescence intensity of the BaAlF5:Eu2+ and BaSiF6:Eu2+ nanophosphors at 359 nm [4f7(6P7/2)→4f7(8S7/2) transition of Eu2+] displays dramatic luminescent quenching. The BaAlF5:Eu2+@PEI or BaSiF6:Eu2+@PEI nanophosphor downconversion luminescent sensors show great sensitivity and selectivity and good linearity, and the detection limits of TNP are 0.57 and 2.82 ng/mL, respectively. The luminescent spectra of BaAlF5:Eu2+ nanophosphors are decreased with increasing the concentration of TNP (1–15 ng/mL) at 359 nm (6P7/2-8S7/2) and present a good linear relationship between the concentration of TNP and luminescent intensity. It proves that the TNP can be detected via luminescence quenching of BaAlF5:Eu2+ nanophosphors by using a LRET system. The luminescent intensity of nanophosphors after adding different concentrations of TNP via Siskowski experiential equation can be fitted well. The curve is y=1.27×105−3.7338×104×ln(1+c/9.88), R2 = 0.99, the luminescent intensity of BaAlF5:Eu2+ nanophosphors and TNP concentrations (1–5 ng/mL) show a good linear relationship, and the detection limit of the TNP is 0.57 ng/mL. [Display omitted]