In this paper,we designed Eu^(2+)-doped BaAlF_(5) and BaSiF_(6) 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 BaAlF_(5):Eu^(2+) and BaSiF_(6):Eu^(2+) nanophosphors are used as energy donors and TNP is an energy acceptor.With increasing TNP concentrations,the luminescence intensity of the BaAlF5:Eu^(2+) and BaSiF6:Eu^(2+) nanophosphors at 359 nm [^(4)f_(7)(^(6)P_(7/2))→^(4)f_(7)(^(8)S_(7/2)) transition of Eu^(2+)] displays dramatic luminescent quenching.The BaAlF_(5):Eu^(2+)@PEI or BaSiF_(6):Eu^(2+)@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.
