A Zn-coordination polymer as a multifunctional fluorescent probe for the detection of V2O74−, Fe3+, and p-nitrotoluene

Abstract

A transition metal coordination polymer, [Zn(tpba)(bqdbc)_0.5]_n (1), was successfully designed and synthesized based on 2,2′-biquinoline-4,4′-dicarboxylic acid (H₂bqdc) and 4-(2,2′;6′,2′-terpyridin)-4′-yl)benzoic acid (Htpba). Compound 1 is initially constructed from the 1D chain of tpba⁻ and bqdc²⁻ and further connected by π⋯π interactions, forming a 2D layered structure. Notably, compound 1 showed good fluorescence stability ranging from pH 1 to 13 in an aqueous solution. It was found that compound 1 could not only detect V₂O₇⁴⁻ ions with high selectivity and recyclability but also serve as an excellent selective sensing material for Fe³⁺ among some cations. More crucially, it is the first time that a luminescent coordination polymer has been used to detect V₂O₇⁴⁻ ions in aqueous solution. The detection of nitrotoluene (p-NT) demonstrated that compound 1 could also behave as a functional probe with high selectivity, sensitivity, and recyclability; and the detection limit of p-NT was 50.9 nM. Meanwhile, the luminescence sensing mechanisms for different analytes were speculated in detail.