A Eu coordination polymer sensor for the detection of tartrazine, folic acid, and amino acids

In this work, 3-(2,4-dicarboxyphenyl)-6-carboxypyridine (H2ppda) and 4-(4-carboxyphenyl)benzoic acid (H2bpdc) were selected to synthesize a two-dimensional layered coordination polymer, [Eu(ppda)(bpdc)0.5(C2H5OH)(H2O)]n (Eu-1). Eu-1 is further hydrogen-bonded to construct a three-dimensional supramolecular structure. It has found that Eu-1 can be used as an excellent fluorescence sensor for the determination of food additives, such as tartrazine (TA), folic acid (FA), arginine (Arg), and lysine (Lys). Eu-1 showed high sensitivity, selectivity, recyclability, and anti-interference for the detection of TA, FA, Arg, and Lys in aqueous solution. The limits of detection TA, FA, Arg, and Lys are 9.87 × 10-8 M, 3.28 × 10−8 M, 2.20 × 10-6 M, and 9.46 × 10-7 M, respectively. Notably, it is the first example of luminescent coordination polymer to identify TA in aqueous system. In the meantime, a film utilizing Eu-1 as the key component had been successfully fabricated, and exhibited a remarkable potential for the visual recognition of TA and FA. In addition, the luminescence sensing mechanisms of Eu-1 on the above analytes were investigated further in detail.