Two fluorescent lead phosphonates for highly selective sensing of nitroaromatics (NACs), Fe3+ and MnO4− ions

Abstract

Two novel lead(II) phosphonates with a 2D double-layer and a 3D framework structure, namely, [Pb(BPDP)] (1) and [Pb₃(BPDP)_1.5(OOCC₆H₄COOH)₃] (2) (H₂BPDP = 4,4′-biphenyldiphosphonate(monoethyl ester), H₂bdc = HOOCC₆H₄COOH), have been synthesized under hydrothermal conditions. Compounds 1 and 2 are stable in air and insoluble in water. Thermogravimetric analyses reveal that compounds 1 and 2 remain unchanged up to about 233 °C and 212 °C, respectively. Luminescence explorations demonstrated that compounds 1 and 2 exhibit highly selective and sensitive sensing for nitroaromatics (NACs). In ion recognition, the choice of solvent for compounds 1 and 2 has a different effect. Experiments proved that the identification of compounds 1 and 2 in aqueous solution is superior to that in ethanol solution. Moreover, compounds 1 and 2 also exhibit highly selective and sensitive sensing for Fe³⁺ and MnO₄⁻. These results reveal that compounds 1 and 2 may be excellent fluorescent sensors for p-NP, Fe³⁺, and MnO₄⁻.